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1. Legal
Copyright © 2012-2023
Copies of this document may be made for your own use and for distribution to others, provided that you do not charge any fee for such copies and further provided that each copy contains this Copyright Notice, whether distributed in print or electronically.
2. Getting Help
If you have trouble with Spring Boot, we would like to help.
-
Try the How-to documents. They provide solutions to the most common questions.
-
Learn the Spring basics. Spring Boot builds on many other Spring projects. Check the spring.io web-site for a wealth of reference documentation. If you are starting out with Spring, try one of the guides.
-
Ask a question. We monitor stackoverflow.com for questions tagged with
spring-boot
. -
Report bugs with Spring Boot at github.com/spring-projects/spring-boot/issues.
All of Spring Boot is open source, including the documentation. If you find problems with the docs or if you want to improve them, please get involved. |
3. Documentation Overview
This section provides a brief overview of Spring Boot reference documentation. It serves as a map for the rest of the document.
The latest copy of this document is available at docs.spring.io/spring-boot/docs/current/reference/.
3.1. First Steps
If you are getting started with Spring Boot or 'Spring' in general, start with the following topics:
-
From scratch: Overview | Requirements | Installation
3.2. Upgrading From an Earlier Version
You should always ensure that you are running a supported version of Spring Boot.
Depending on the version that you are upgrading to, you can find some additional tips here:
-
From 1.x: Upgrading from 1.x
-
To a new feature release: Upgrading to New Feature Release
-
Spring Boot CLI: Upgrading the Spring Boot CLI
3.3. Developing With Spring Boot
Ready to actually start using Spring Boot? We have you covered:
-
Best practices: Code Structure | @Configuration | @EnableAutoConfiguration | Beans and Dependency Injection
-
Packaging your app: Production jars
-
Spring Boot CLI: Using the CLI
3.4. Learning About Spring Boot Features
Need more details about Spring Boot’s core features? The following content is for you:
-
Spring Application: SpringApplication
-
External Configuration: External Configuration
-
Profiles: Profiles
-
Logging: Logging
3.5. Web
If you develop Spring Boot web applications, take a look at the following content:
-
Servlet Web Applications: Spring MVC, Jersey, Embedded Servlet Containers
-
Reactive Web Applications: Spring Webflux, Embedded Servlet Containers
-
Graceful Shutdown: Graceful Shutdown
-
Spring Security: Default Security Configuration, Auto-configuration for OAuth2, SAML
-
Spring Session: Auto-configuration for Spring Session
-
Spring HATEOAS: Auto-configuration for Spring HATEOAS
3.7. Messaging
If your application uses any messaging protocol, see one or more of the following sections:
3.8. IO
If your application needs IO capabilities, see one or more of the following sections:
-
Caching: Caching support with EhCache, Hazelcast, Infinispan, and more
-
Quartz: Quartz Scheduling
-
Mail: Sending Email
-
Validation: JSR-303 Validation
-
REST Clients: Calling REST Services with RestTemplate and WebClient
-
Webservices: Auto-configuration for Spring Web Services
3.9. Container Images
Spring Boot provides first-class support for building efficient container images. You can read more about it here:
-
Efficient Container Images: Tips to optimize container images such as Docker images
-
Dockerfiles: Building container images using dockerfiles
-
Cloud Native Buildpacks: Support for Cloud Native Buildpacks with Maven and Gradle
3.10. Moving to Production
When you are ready to push your Spring Boot application to production, we have some tricks that you might like:
3.11. GraalVM Native Images
Spring Boot applications can be converted into native executables using GraalVM. You can read more about our native image support here:
-
GraalVM Native Images: Introduction | Key Differences with the JVM | Ahead-of-Time Processing
-
Getting Started: Buildpacks | Native Build Tools
-
Testing: JVM | Native Build Tools
-
Advanced Topics: Nested Configuration Properties | Converting JARs | Known Limitations
3.12. Advanced Topics
Finally, we have a few topics for more advanced users:
-
Spring Boot Applications Deployment: Cloud Deployment | OS Service
-
Appendix: Application Properties | Configuration Metadata | Auto-configuration Classes | Test Auto-configuration Annotations | Executable Jars | Dependency Versions
4. Getting Started
If you are getting started with Spring Boot, or “Spring” in general, start by reading this section. It answers the basic “what?”, “how?” and “why?” questions. It includes an introduction to Spring Boot, along with installation instructions. We then walk you through building your first Spring Boot application, discussing some core principles as we go.
4.1. Introducing Spring Boot
Spring Boot helps you to create stand-alone, production-grade Spring-based applications that you can run. We take an opinionated view of the Spring platform and third-party libraries, so that you can get started with minimum fuss. Most Spring Boot applications need very little Spring configuration.
You can use Spring Boot to create Java applications that can be started by using java -jar
or more traditional war deployments.
Our primary goals are:
-
Provide a radically faster and widely accessible getting-started experience for all Spring development.
-
Be opinionated out of the box but get out of the way quickly as requirements start to diverge from the defaults.
-
Provide a range of non-functional features that are common to large classes of projects (such as embedded servers, security, metrics, health checks, and externalized configuration).
-
Absolutely no code generation (when not targeting native image) and no requirement for XML configuration.
4.2. System Requirements
Spring Boot 3.2.0-SNAPSHOT requires Java 17 and is compatible up to and including Java 21. Spring Framework 6.1.1 or above is also required.
Explicit build support is provided for the following build tools:
Build Tool | Version |
---|---|
Maven |
3.6.3 or later |
Gradle |
7.x (7.5 or later) and 8.x |
4.2.1. Servlet Containers
Spring Boot supports the following embedded servlet containers:
Name | Servlet Version |
---|---|
Tomcat 10.1 |
6.0 |
Jetty 12.0 |
6.0 |
Undertow 2.3 |
6.0 |
You can also deploy Spring Boot applications to any servlet 5.0+ compatible container.
4.2.2. GraalVM Native Images
Spring Boot applications can be converted into a Native Image using GraalVM 22.3 or above.
Images can be created using the native build tools Gradle/Maven plugins or native-image
tool provided by GraalVM.
You can also create native images using the native-image Paketo buildpack.
The following versions are supported:
Name | Version |
---|---|
GraalVM Community |
22.3 |
Native Build Tools |
0.9.28 |
4.3. Installing Spring Boot
Spring Boot can be used with “classic” Java development tools or installed as a command line tool. Either way, you need Java SDK v17 or higher. Before you begin, you should check your current Java installation by using the following command:
$ java -version
If you are new to Java development or if you want to experiment with Spring Boot, you might want to try the Spring Boot CLI (Command Line Interface) first. Otherwise, read on for “classic” installation instructions.
4.3.1. Installation Instructions for the Java Developer
You can use Spring Boot in the same way as any standard Java library.
To do so, include the appropriate spring-boot-*.jar
files on your classpath.
Spring Boot does not require any special tools integration, so you can use any IDE or text editor.
Also, there is nothing special about a Spring Boot application, so you can run and debug a Spring Boot application as you would any other Java program.
Although you could copy Spring Boot jars, we generally recommend that you use a build tool that supports dependency management (such as Maven or Gradle).
Maven Installation
Spring Boot is compatible with Apache Maven 3.6.3 or later. If you do not already have Maven installed, you can follow the instructions at maven.apache.org.
On many operating systems, Maven can be installed with a package manager.
If you use OSX Homebrew, try brew install maven .
Ubuntu users can run sudo apt-get install maven .
Windows users with Chocolatey can run choco install maven from an elevated (administrator) prompt.
|
Spring Boot dependencies use the org.springframework.boot
group id.
Typically, your Maven POM file inherits from the spring-boot-starter-parent
project and declares dependencies to one or more “Starters”.
Spring Boot also provides an optional Maven plugin to create executable jars.
More details on getting started with Spring Boot and Maven can be found in the Getting Started section of the Maven plugin’s reference guide.
Gradle Installation
Spring Boot is compatible with Gradle 7.x (7.5 or later) and 8.x. If you do not already have Gradle installed, you can follow the instructions at gradle.org.
Spring Boot dependencies can be declared by using the org.springframework.boot
group
.
Typically, your project declares dependencies to one or more “Starters”.
Spring Boot provides a useful Gradle plugin that can be used to simplify dependency declarations and to create executable jars.
More details on getting started with Spring Boot and Gradle can be found in the Getting Started section of the Gradle plugin’s reference guide.
4.3.2. Installing the Spring Boot CLI
The Spring Boot CLI (Command Line Interface) is a command line tool that you can use to quickly prototype with Spring.
You do not need to use the CLI to work with Spring Boot, but it is a quick way to get a Spring application off the ground without an IDE.
Manual Installation
You can download one of the spring-boot-cli-*-bin.zip
or spring-boot-cli-*-bin.tar.gz
files from the Spring software repository.
Once downloaded, follow the INSTALL.txt instructions from the unpacked archive.
In summary, there is a spring
script (spring.bat
for Windows) in a bin/
directory in the .zip
file.
Alternatively, you can use java -jar
with the .jar
file (the script helps you to be sure that the classpath is set correctly).
Installation with SDKMAN!
SDKMAN! (The Software Development Kit Manager) can be used for managing multiple versions of various binary SDKs, including Groovy and the Spring Boot CLI. Get SDKMAN! from sdkman.io and install Spring Boot by using the following commands:
$ sdk install springboot
$ spring --version
Spring CLI v3.2.0-SNAPSHOT
If you develop features for the CLI and want access to the version you built, use the following commands:
$ sdk install springboot dev /path/to/spring-boot/spring-boot-cli/target/spring-boot-cli-3.2.0-SNAPSHOT-bin/spring-3.2.0-SNAPSHOT/
$ sdk default springboot dev
$ spring --version
Spring CLI v3.2.0-SNAPSHOT
The preceding instructions install a local instance of spring
called the dev
instance.
It points at your target build location, so every time you rebuild Spring Boot, spring
is up-to-date.
You can see it by running the following command:
$ sdk ls springboot
================================================================================
Available Springboot Versions
================================================================================
> + dev
* 3.2.0-SNAPSHOT
================================================================================
+ - local version
* - installed
> - currently in use
================================================================================
OSX Homebrew Installation
If you are on a Mac and use Homebrew, you can install the Spring Boot CLI by using the following commands:
$ brew tap spring-io/tap
$ brew install spring-boot
Homebrew installs spring
to /usr/local/bin
.
If you do not see the formula, your installation of brew might be out-of-date.
In that case, run brew update and try again.
|
MacPorts Installation
If you are on a Mac and use MacPorts, you can install the Spring Boot CLI by using the following command:
$ sudo port install spring-boot-cli
Command-line Completion
The Spring Boot CLI includes scripts that provide command completion for the BASH and zsh shells.
You can source
the script (also named spring
) in any shell or put it in your personal or system-wide bash completion initialization.
On a Debian system, the system-wide scripts are in <installation location>/shell-completion/bash
and all scripts in that directory are executed when a new shell starts.
For example, to run the script manually if you have installed by using SDKMAN!, use the following commands:
$ . ~/.sdkman/candidates/springboot/current/shell-completion/bash/spring
$ spring <HIT TAB HERE>
grab help jar run test version
If you install the Spring Boot CLI by using Homebrew or MacPorts, the command-line completion scripts are automatically registered with your shell. |
Windows Scoop Installation
If you are on a Windows and use Scoop, you can install the Spring Boot CLI by using the following commands:
> scoop bucket add extras > scoop install springboot
Scoop installs spring
to ~/scoop/apps/springboot/current/bin
.
If you do not see the app manifest, your installation of scoop might be out-of-date.
In that case, run scoop update and try again.
|
4.4. Developing Your First Spring Boot Application
This section describes how to develop a small “Hello World!” web application that highlights some of Spring Boot’s key features. You can choose between Maven or Gradle as the build system.
The spring.io website contains many “Getting Started” guides that use Spring Boot. If you need to solve a specific problem, check there first. You can shortcut the steps below by going to start.spring.io and choosing the "Web" starter from the dependencies searcher. Doing so generates a new project structure so that you can start coding right away. Check the start.spring.io user guide for more details. |
4.4.1. Prerequisites
Before we begin, open a terminal and run the following commands to ensure that you have a valid version of Java installed:
$ java -version
openjdk version "17.0.4.1" 2022-08-12 LTS
OpenJDK Runtime Environment (build 17.0.4.1+1-LTS)
OpenJDK 64-Bit Server VM (build 17.0.4.1+1-LTS, mixed mode, sharing)
This sample needs to be created in its own directory. Subsequent instructions assume that you have created a suitable directory and that it is your current directory. |
Maven
If you want to use Maven, ensure that you have Maven installed:
$ mvn -v
Apache Maven 3.8.5 (3599d3414f046de2324203b78ddcf9b5e4388aa0)
Maven home: usr/Users/developer/tools/maven/3.8.5
Java version: 17.0.4.1, vendor: BellSoft, runtime: /Users/developer/sdkman/candidates/java/17.0.4.1-librca
Gradle
If you want to use Gradle, ensure that you have Gradle installed:
$ gradle --version
------------------------------------------------------------
Gradle 8.1.1
------------------------------------------------------------
Build time: 2023-04-21 12:31:26 UTC
Revision: 1cf537a851c635c364a4214885f8b9798051175b
Kotlin: 1.8.10
Groovy: 3.0.15
Ant: Apache Ant(TM) version 1.10.11 compiled on July 10 2021
JVM: 17.0.7 (BellSoft 17.0.7+7-LTS)
OS: Linux 6.2.12-200.fc37.aarch64 aarch64
4.4.2. Setting up the project with Maven
We need to start by creating a Maven pom.xml
file.
The pom.xml
is the recipe that is used to build your project.
Open your favorite text editor and add the following:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.example</groupId>
<artifactId>myproject</artifactId>
<version>0.0.1-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>3.2.0-SNAPSHOT</version>
</parent>
<!-- Additional lines to be added here... -->
<!-- (you only need this if you are using a milestone or snapshot version) -->
<repositories>
<repository>
<id>spring-snapshots</id>
<url>https://repo.spring.io/snapshot</url>
<snapshots><enabled>true</enabled></snapshots>
</repository>
<repository>
<id>spring-milestones</id>
<url>https://repo.spring.io/milestone</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-snapshots</id>
<url>https://repo.spring.io/snapshot</url>
</pluginRepository>
<pluginRepository>
<id>spring-milestones</id>
<url>https://repo.spring.io/milestone</url>
</pluginRepository>
</pluginRepositories>
</project>
The preceding listing should give you a working build.
You can test it by running mvn package
(for now, you can ignore the “jar will be empty - no content was marked for inclusion!” warning).
At this point, you could import the project into an IDE (most modern Java IDEs include built-in support for Maven). For simplicity, we continue to use a plain text editor for this example. |
4.4.3. Setting up the project with Gradle
We need to start by creating a Gradle build.gradle
file.
The build.gradle
is the build script that is used to build your project.
Open your favorite text editor and add the following:
plugins {
id 'java'
id 'org.springframework.boot' version '3.2.0-SNAPSHOT'
}
apply plugin: 'io.spring.dependency-management'
group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '17'
repositories {
mavenCentral()
maven { url 'https://repo.spring.io/milestone' }
maven { url 'https://repo.spring.io/snapshot' }
}
dependencies {
}
The preceding listing should give you a working build.
You can test it by running gradle classes
.
At this point, you could import the project into an IDE (most modern Java IDEs include built-in support for Gradle). For simplicity, we continue to use a plain text editor for this example. |
4.4.4. Adding Classpath Dependencies
Spring Boot provides a number of “Starters” that let you add jars to your classpath. “Starters” provide dependencies that you are likely to need when developing a specific type of application.
Maven
Most Spring Boot applications use the spring-boot-starter-parent
in the parent
section of the POM.
The spring-boot-starter-parent
is a special starter that provides useful Maven defaults.
It also provides a dependency-management
section so that you can omit version
tags for “blessed” dependencies.
Since we are developing a web application, we add a spring-boot-starter-web
dependency.
Before that, we can look at what we currently have by running the following command:
$ mvn dependency:tree
[INFO] com.example:myproject:jar:0.0.1-SNAPSHOT
The mvn dependency:tree
command prints a tree representation of your project dependencies.
You can see that spring-boot-starter-parent
provides no dependencies by itself.
To add the necessary dependencies, edit your pom.xml
and add the spring-boot-starter-web
dependency immediately below the parent
section:
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
If you run mvn dependency:tree
again, you see that there are now a number of additional dependencies, including the Tomcat web server and Spring Boot itself.
Gradle
Most Spring Boot applications use the org.springframework.boot
Gradle plugin.
This plugin provides useful defaults and Gradle tasks.
The io.spring.dependency-management
Gradle plugin provides dependency management so that you can omit version
tags for “blessed” dependencies.
Since we are developing a web application, we add a spring-boot-starter-web
dependency.
Before that, we can look at what we currently have by running the following command:
$ gradle dependencies
> Task :dependencies
------------------------------------------------------------
Root project 'myproject'
------------------------------------------------------------
The gradle dependencies
command prints a tree representation of your project dependencies.
Right now, the project has no dependencies.
To add the necessary dependencies, edit your build.gradle
and add the spring-boot-starter-web
dependency in the dependencies
section:
dependencies {
implementation 'org.springframework.boot:spring-boot-starter-web'
}
If you run gradle dependencies
again, you see that there are now a number of additional dependencies, including the Tomcat web server and Spring Boot itself.
4.4.5. Writing the Code
To finish our application, we need to create a single Java file.
By default, Maven and Gradle compile sources from src/main/java
, so you need to create that directory structure and then add a file named src/main/java/MyApplication.java
to contain the following code:
package com.example;
@RestController
@SpringBootApplication
public class MyApplication {
@RequestMapping("/")
String home() {
return "Hello World!";
}
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
@RestController
@SpringBootApplication
class MyApplication {
@RequestMapping("/")
fun home() = "Hello World!"
}
fun main(args: Array<String>) {
runApplication<MyApplication>(*args)
}
Although there is not much code here, quite a lot is going on. We step through the important parts in the next few sections.
The @RestController and @RequestMapping Annotations
The first annotation on our MyApplication
class is @RestController
.
This is known as a stereotype annotation.
It provides hints for people reading the code and for Spring that the class plays a specific role.
In this case, our class is a web @Controller
, so Spring considers it when handling incoming web requests.
The @RequestMapping
annotation provides “routing” information.
It tells Spring that any HTTP request with the /
path should be mapped to the home
method.
The @RestController
annotation tells Spring to render the resulting string directly back to the caller.
The @RestController and @RequestMapping annotations are Spring MVC annotations (they are not specific to Spring Boot).
See the MVC section in the Spring Reference Documentation for more details.
|
The @SpringBootApplication Annotation
The second class-level annotation is @SpringBootApplication
.
This annotation is known as a meta-annotation, it combines @SpringBootConfiguration
, @EnableAutoConfiguration
and @ComponentScan
.
Of those, the annotation we’re most interested in here is @EnableAutoConfiguration
.
@EnableAutoConfiguration
tells Spring Boot to “guess” how you want to configure Spring, based on the jar dependencies that you have added.
Since spring-boot-starter-web
added Tomcat and Spring MVC, the auto-configuration assumes that you are developing a web application and sets up Spring accordingly.
The “main” Method
The final part of our application is the main
method.
This is a standard method that follows the Java convention for an application entry point.
Our main method delegates to Spring Boot’s SpringApplication
class by calling run
.
SpringApplication
bootstraps our application, starting Spring, which, in turn, starts the auto-configured Tomcat web server.
We need to pass MyApplication.class
as an argument to the run
method to tell SpringApplication
which is the primary Spring component.
The args
array is also passed through to expose any command-line arguments.
4.4.6. Running the Example
Maven
At this point, your application should work.
Since you used the spring-boot-starter-parent
POM, you have a useful run
goal that you can use to start the application.
Type mvn spring-boot:run
from the root project directory to start the application.
You should see output similar to the following:
$ mvn spring-boot:run
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v3.2.0-SNAPSHOT)
....... . . .
....... . . . (log output here)
....... . . .
........ Started MyApplication in 0.906 seconds (process running for 6.514)
If you open a web browser to localhost:8080
, you should see the following output:
Hello World!
To gracefully exit the application, press ctrl-c
.
Gradle
At this point, your application should work.
Since you used the org.springframework.boot
Gradle plugin, you have a useful bootRun
goal that you can use to start the application.
Type gradle bootRun
from the root project directory to start the application.
You should see output similar to the following:
$ gradle bootRun
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v3.2.0-SNAPSHOT)
....... . . .
....... . . . (log output here)
....... . . .
........ Started MyApplication in 0.906 seconds (process running for 6.514)
If you open a web browser to localhost:8080
, you should see the following output:
Hello World!
To gracefully exit the application, press ctrl-c
.
4.4.7. Creating an Executable Jar
We finish our example by creating a completely self-contained executable jar file that we could run in production. Executable jars (sometimes called “uber jars” or “fat jars”) are archives containing your compiled classes along with all of the jar dependencies that your code needs to run.
Maven
To create an executable jar, we need to add the spring-boot-maven-plugin
to our pom.xml
.
To do so, insert the following lines just below the dependencies
section:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
The spring-boot-starter-parent POM includes <executions> configuration to bind the repackage goal.
If you do not use the parent POM, you need to declare this configuration yourself.
See the plugin documentation for details.
|
Save your pom.xml
and run mvn package
from the command line, as follows:
$ mvn package
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building myproject 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] .... ..
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ myproject ---
[INFO] Building jar: /Users/developer/example/spring-boot-example/target/myproject-0.0.1-SNAPSHOT.jar
[INFO]
[INFO] --- spring-boot-maven-plugin:3.2.0-SNAPSHOT:repackage (default) @ myproject ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
If you look in the target
directory, you should see myproject-0.0.1-SNAPSHOT.jar
.
The file should be around 18 MB in size.
If you want to peek inside, you can use jar tvf
, as follows:
$ jar tvf target/myproject-0.0.1-SNAPSHOT.jar
You should also see a much smaller file named myproject-0.0.1-SNAPSHOT.jar.original
in the target
directory.
This is the original jar file that Maven created before it was repackaged by Spring Boot.
To run that application, use the java -jar
command, as follows:
$ java -jar target/myproject-0.0.1-SNAPSHOT.jar
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v3.2.0-SNAPSHOT)
....... . . .
....... . . . (log output here)
....... . . .
........ Started MyApplication in 0.999 seconds (process running for 1.253)
As before, to exit the application, press ctrl-c
.
Gradle
To create an executable jar, we need to run gradle bootJar
from the command line, as follows:
$ gradle bootJar
BUILD SUCCESSFUL in 639ms
3 actionable tasks: 3 executed
If you look in the build/libs
directory, you should see myproject-0.0.1-SNAPSHOT.jar
.
The file should be around 18 MB in size.
If you want to peek inside, you can use jar tvf
, as follows:
$ jar tvf build/libs/myproject-0.0.1-SNAPSHOT.jar
To run that application, use the java -jar
command, as follows:
$ java -jar build/libs/myproject-0.0.1-SNAPSHOT.jar
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v3.2.0-SNAPSHOT)
....... . . .
....... . . . (log output here)
....... . . .
........ Started MyApplication in 0.999 seconds (process running for 1.253)
As before, to exit the application, press ctrl-c
.
4.5. What to Read Next
Hopefully, this section provided some of the Spring Boot basics and got you on your way to writing your own applications. If you are a task-oriented type of developer, you might want to jump over to spring.io and follow some of the getting started guides that solve specific “How do I do that with Spring?” problems. We also have Spring Boot-specific “How-to” reference documentation.
Otherwise, the next logical step is to read Developing with Spring Boot. If you are really impatient, you could also jump ahead and read about Spring Boot features.
5. Upgrading Spring Boot
Instructions for how to upgrade from earlier versions of Spring Boot are provided on the project wiki. Follow the links in the release notes section to find the version that you want to upgrade to.
Upgrading instructions are always the first item in the release notes. If you are more than one release behind, please make sure that you also review the release notes of the versions that you jumped.
5.1. Upgrading From 1.x
If you are upgrading from the 1.x
release of Spring Boot, check the “migration guide” on the project wiki that provides detailed upgrade instructions.
Check also the “release notes” for a list of “new and noteworthy” features for each release.
5.2. Upgrading to a New Feature Release
When upgrading to a new feature release, some properties may have been renamed or removed. Spring Boot provides a way to analyze your application’s environment and print diagnostics at startup, but also temporarily migrate properties at runtime for you. To enable that feature, add the following dependency to your project:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-properties-migrator</artifactId>
<scope>runtime</scope>
</dependency>
Properties that are added late to the environment, such as when using @PropertySource , will not be taken into account.
|
Once you finish the migration, please make sure to remove this module from your project’s dependencies. |
5.3. Upgrading the Spring Boot CLI
To upgrade an existing CLI installation, use the appropriate package manager command (for example, brew upgrade
).
If you manually installed the CLI, follow the standard instructions, remembering to update your PATH
environment variable to remove any older references.
5.4. What to Read Next
Once you’ve decided to upgrade your application, you can find detailed information regarding specific features in the rest of the document.
Spring Boot’s documentation is specific to that version, so any information that you find in here will contain the most up-to-date changes that are in that version.
6. Developing with Spring Boot
This section goes into more detail about how you should use Spring Boot. It covers topics such as build systems, auto-configuration, and how to run your applications. We also cover some Spring Boot best practices. Although there is nothing particularly special about Spring Boot (it is just another library that you can consume), there are a few recommendations that, when followed, make your development process a little easier.
If you are starting out with Spring Boot, you should probably read the Getting Started guide before diving into this section.
6.1. Build Systems
It is strongly recommended that you choose a build system that supports dependency management and that can consume artifacts published to the “Maven Central” repository. We would recommend that you choose Maven or Gradle. It is possible to get Spring Boot to work with other build systems (Ant, for example), but they are not particularly well supported.
6.1.1. Dependency Management
Each release of Spring Boot provides a curated list of dependencies that it supports. In practice, you do not need to provide a version for any of these dependencies in your build configuration, as Spring Boot manages that for you. When you upgrade Spring Boot itself, these dependencies are upgraded as well in a consistent way.
You can still specify a version and override Spring Boot’s recommendations if you need to do so. |
The curated list contains all the Spring modules that you can use with Spring Boot as well as a refined list of third party libraries.
The list is available as a standard Bills of Materials (spring-boot-dependencies
) that can be used with both Maven and Gradle.
Each release of Spring Boot is associated with a base version of the Spring Framework. We highly recommend that you do not specify its version. |
6.1.2. Maven
To learn about using Spring Boot with Maven, see the documentation for Spring Boot’s Maven plugin:
6.1.3. Gradle
To learn about using Spring Boot with Gradle, see the documentation for Spring Boot’s Gradle plugin:
6.1.4. Ant
It is possible to build a Spring Boot project using Apache Ant+Ivy.
The spring-boot-antlib
“AntLib” module is also available to help Ant create executable jars.
To declare dependencies, a typical ivy.xml
file looks something like the following example:
<ivy-module version="2.0">
<info organisation="org.springframework.boot" module="spring-boot-sample-ant" />
<configurations>
<conf name="compile" description="everything needed to compile this module" />
<conf name="runtime" extends="compile" description="everything needed to run this module" />
</configurations>
<dependencies>
<dependency org="org.springframework.boot" name="spring-boot-starter"
rev="${spring-boot.version}" conf="compile" />
</dependencies>
</ivy-module>
A typical build.xml
looks like the following example:
<project
xmlns:ivy="antlib:org.apache.ivy.ant"
xmlns:spring-boot="antlib:org.springframework.boot.ant"
name="myapp" default="build">
<property name="spring-boot.version" value="3.2.0-SNAPSHOT" />
<target name="resolve" description="--> retrieve dependencies with ivy">
<ivy:retrieve pattern="lib/[conf]/[artifact]-[type]-[revision].[ext]" />
</target>
<target name="classpaths" depends="resolve">
<path id="compile.classpath">
<fileset dir="lib/compile" includes="*.jar" />
</path>
</target>
<target name="init" depends="classpaths">
<mkdir dir="build/classes" />
</target>
<target name="compile" depends="init" description="compile">
<javac srcdir="src/main/java" destdir="build/classes" classpathref="compile.classpath" />
</target>
<target name="build" depends="compile">
<spring-boot:exejar destfile="build/myapp.jar" classes="build/classes">
<spring-boot:lib>
<fileset dir="lib/runtime" />
</spring-boot:lib>
</spring-boot:exejar>
</target>
</project>
If you do not want to use the spring-boot-antlib module, see the Build an Executable Archive From Ant without Using spring-boot-antlib “How-to” .
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6.1.5. Starters
Starters are a set of convenient dependency descriptors that you can include in your application.
You get a one-stop shop for all the Spring and related technologies that you need without having to hunt through sample code and copy-paste loads of dependency descriptors.
For example, if you want to get started using Spring and JPA for database access, include the spring-boot-starter-data-jpa
dependency in your project.
The starters contain a lot of the dependencies that you need to get a project up and running quickly and with a consistent, supported set of managed transitive dependencies.
The following application starters are provided by Spring Boot under the org.springframework.boot
group:
Name | Description |
---|---|
Core starter, including auto-configuration support, logging and YAML |
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Starter for JMS messaging using Apache ActiveMQ |
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Starter for using Spring AMQP and Rabbit MQ |
|
Starter for aspect-oriented programming with Spring AOP and AspectJ |
|
Starter for JMS messaging using Apache Artemis |
|
Starter for using Spring Batch |
|
Starter for using Spring Framework’s caching support |
|
Starter for using Cassandra distributed database and Spring Data Cassandra |
|
Starter for using Cassandra distributed database and Spring Data Cassandra Reactive |
|
Starter for using Couchbase document-oriented database and Spring Data Couchbase |
|
Starter for using Couchbase document-oriented database and Spring Data Couchbase Reactive |
|
Starter for using Elasticsearch search and analytics engine and Spring Data Elasticsearch |
|
Starter for using Spring Data JDBC |
|
Starter for using Spring Data JPA with Hibernate |
|
Starter for using Spring Data LDAP |
|
Starter for using MongoDB document-oriented database and Spring Data MongoDB |
|
Starter for using MongoDB document-oriented database and Spring Data MongoDB Reactive |
|
Starter for using Neo4j graph database and Spring Data Neo4j |
|
Starter for using Spring Data R2DBC |
|
Starter for using Redis key-value data store with Spring Data Redis and the Lettuce client |
|
Starter for using Redis key-value data store with Spring Data Redis reactive and the Lettuce client |
|
Starter for exposing Spring Data repositories over REST using Spring Data REST and Spring MVC |
|
Starter for building MVC web applications using FreeMarker views |
|
Starter for building GraphQL applications with Spring GraphQL |
|
Starter for building MVC web applications using Groovy Templates views |
|
Starter for building hypermedia-based RESTful web application with Spring MVC and Spring HATEOAS |
|
Starter for using Spring Integration |
|
Starter for using JDBC with the HikariCP connection pool |
|
Starter for building RESTful web applications using JAX-RS and Jersey. An alternative to |
|
Starter for using jOOQ to access SQL databases with JDBC. An alternative to |
|
Starter for reading and writing json |
|
Starter for using Java Mail and Spring Framework’s email sending support |
|
Starter for building web applications using Mustache views |
|
Starter for using Spring Authorization Server features |
|
Starter for using Spring Security’s OAuth2/OpenID Connect client features |
|
Starter for using Spring Security’s OAuth2 resource server features |
|
Starter for using Spring for Apache Pulsar |
|
Starter for using Spring for Apache Pulsar Reactive |
|
Starter for using the Quartz scheduler |
|
Starter for building RSocket clients and servers |
|
Starter for using Spring Security |
|
Starter for testing Spring Boot applications with libraries including JUnit Jupiter, Hamcrest and Mockito |
|
Starter for building MVC web applications using Thymeleaf views |
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Starter for using Java Bean Validation with Hibernate Validator |
|
Starter for building web, including RESTful, applications using Spring MVC. Uses Tomcat as the default embedded container |
|
Starter for using Spring Web Services |
|
Starter for building WebFlux applications using Spring Framework’s Reactive Web support |
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Starter for building WebSocket applications using Spring Framework’s MVC WebSocket support |
In addition to the application starters, the following starters can be used to add production ready features:
Name | Description |
---|---|
Starter for using Spring Boot’s Actuator which provides production ready features to help you monitor and manage your application |
Finally, Spring Boot also includes the following starters that can be used if you want to exclude or swap specific technical facets:
Name | Description |
---|---|
Starter for using Jetty as the embedded servlet container. An alternative to |
|
Starter for using Log4j2 for logging. An alternative to |
|
Starter for logging using Logback. Default logging starter |
|
Starter for using Reactor Netty as the embedded reactive HTTP server. |
|
Starter for using Tomcat as the embedded servlet container. Default servlet container starter used by |
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Starter for using Undertow as the embedded servlet container. An alternative to |
To learn how to swap technical facets, please see the how-to documentation for swapping web server and logging system.
For a list of additional community contributed starters, see the README file in the spring-boot-starters module on GitHub.
|
6.2. Structuring Your Code
Spring Boot does not require any specific code layout to work. However, there are some best practices that help.
If you wish to enforce a structure based on domains, take a look at Spring Modulith. |
6.2.1. Using the “default” Package
When a class does not include a package
declaration, it is considered to be in the “default package”.
The use of the “default package” is generally discouraged and should be avoided.
It can cause particular problems for Spring Boot applications that use the @ComponentScan
, @ConfigurationPropertiesScan
, @EntityScan
, or @SpringBootApplication
annotations, since every class from every jar is read.
We recommend that you follow Java’s recommended package naming conventions and use a reversed domain name (for example, com.example.project ).
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6.2.2. Locating the Main Application Class
We generally recommend that you locate your main application class in a root package above other classes.
The @SpringBootApplication
annotation is often placed on your main class, and it implicitly defines a base “search package” for certain items.
For example, if you are writing a JPA application, the package of the @SpringBootApplication
annotated class is used to search for @Entity
items.
Using a root package also allows component scan to apply only on your project.
If you do not want to use @SpringBootApplication , the @EnableAutoConfiguration and @ComponentScan annotations that it imports defines that behavior so you can also use those instead.
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The following listing shows a typical layout:
com +- example +- myapplication +- MyApplication.java | +- customer | +- Customer.java | +- CustomerController.java | +- CustomerService.java | +- CustomerRepository.java | +- order +- Order.java +- OrderController.java +- OrderService.java +- OrderRepository.java
The MyApplication.java
file would declare the main
method, along with the basic @SpringBootApplication
, as follows:
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
@SpringBootApplication
class MyApplication
fun main(args: Array<String>) {
runApplication<MyApplication>(*args)
}
6.3. Configuration Classes
Spring Boot favors Java-based configuration.
Although it is possible to use SpringApplication
with XML sources, we generally recommend that your primary source be a single @Configuration
class.
Usually the class that defines the main
method is a good candidate as the primary @Configuration
.
Many Spring configuration examples have been published on the Internet that use XML configuration.
If possible, always try to use the equivalent Java-based configuration.
Searching for Enable* annotations can be a good starting point.
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6.3.1. Importing Additional Configuration Classes
You need not put all your @Configuration
into a single class.
The @Import
annotation can be used to import additional configuration classes.
Alternatively, you can use @ComponentScan
to automatically pick up all Spring components, including @Configuration
classes.
6.4. Auto-configuration
Spring Boot auto-configuration attempts to automatically configure your Spring application based on the jar dependencies that you have added.
For example, if HSQLDB
is on your classpath, and you have not manually configured any database connection beans, then Spring Boot auto-configures an in-memory database.
You need to opt-in to auto-configuration by adding the @EnableAutoConfiguration
or @SpringBootApplication
annotations to one of your @Configuration
classes.
You should only ever add one @SpringBootApplication or @EnableAutoConfiguration annotation.
We generally recommend that you add one or the other to your primary @Configuration class only.
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6.4.1. Gradually Replacing Auto-configuration
Auto-configuration is non-invasive.
At any point, you can start to define your own configuration to replace specific parts of the auto-configuration.
For example, if you add your own DataSource
bean, the default embedded database support backs away.
If you need to find out what auto-configuration is currently being applied, and why, start your application with the --debug
switch.
Doing so enables debug logs for a selection of core loggers and logs a conditions report to the console.
6.4.2. Disabling Specific Auto-configuration Classes
If you find that specific auto-configuration classes that you do not want are being applied, you can use the exclude attribute of @SpringBootApplication
to disable them, as shown in the following example:
@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class })
public class MyApplication {
}
@SpringBootApplication(exclude = [DataSourceAutoConfiguration::class])
class MyApplication
If the class is not on the classpath, you can use the excludeName
attribute of the annotation and specify the fully qualified name instead.
If you prefer to use @EnableAutoConfiguration
rather than @SpringBootApplication
, exclude
and excludeName
are also available.
Finally, you can also control the list of auto-configuration classes to exclude by using the spring.autoconfigure.exclude
property.
You can define exclusions both at the annotation level and by using the property. |
Even though auto-configuration classes are public , the only aspect of the class that is considered public API is the name of the class which can be used for disabling the auto-configuration.
The actual contents of those classes, such as nested configuration classes or bean methods are for internal use only and we do not recommend using those directly.
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6.4.3. Auto-configuration Packages
Auto-configuration packages are the packages that various auto-configured features look in by default when scanning for things such as entities and Spring Data repositories.
The @EnableAutoConfiguration
annotation (either directly or through its presence on @SpringBootApplication
) determines the default auto-configuration package.
Additional packages can be configured using the @AutoConfigurationPackage
annotation.
6.5. Spring Beans and Dependency Injection
You are free to use any of the standard Spring Framework techniques to define your beans and their injected dependencies.
We generally recommend using constructor injection to wire up dependencies and @ComponentScan
to find beans.
If you structure your code as suggested above (locating your application class in a top package), you can add @ComponentScan
without any arguments or use the @SpringBootApplication
annotation which implicitly includes it.
All of your application components (@Component
, @Service
, @Repository
, @Controller
, and others) are automatically registered as Spring Beans.
The following example shows a @Service
Bean that uses constructor injection to obtain a required RiskAssessor
bean:
@Service
public class MyAccountService implements AccountService {
private final RiskAssessor riskAssessor;
public MyAccountService(RiskAssessor riskAssessor) {
this.riskAssessor = riskAssessor;
}
// ...
}
@Service
class MyAccountService(private val riskAssessor: RiskAssessor) : AccountService
If a bean has more than one constructor, you will need to mark the one you want Spring to use with @Autowired
:
@Service
public class MyAccountService implements AccountService {
private final RiskAssessor riskAssessor;
private final PrintStream out;
@Autowired
public MyAccountService(RiskAssessor riskAssessor) {
this.riskAssessor = riskAssessor;
this.out = System.out;
}
public MyAccountService(RiskAssessor riskAssessor, PrintStream out) {
this.riskAssessor = riskAssessor;
this.out = out;
}
// ...
}
@Service
class MyAccountService : AccountService {
private val riskAssessor: RiskAssessor
private val out: PrintStream
@Autowired
constructor(riskAssessor: RiskAssessor) {
this.riskAssessor = riskAssessor
out = System.out
}
constructor(riskAssessor: RiskAssessor, out: PrintStream) {
this.riskAssessor = riskAssessor
this.out = out
}
// ...
}
Notice how using constructor injection lets the riskAssessor field be marked as final , indicating that it cannot be subsequently changed.
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6.6. Using the @SpringBootApplication Annotation
Many Spring Boot developers like their apps to use auto-configuration, component scan and be able to define extra configuration on their "application class".
A single @SpringBootApplication
annotation can be used to enable those three features, that is:
-
@EnableAutoConfiguration
: enable Spring Boot’s auto-configuration mechanism -
@ComponentScan
: enable@Component
scan on the package where the application is located (see the best practices) -
@SpringBootConfiguration
: enable registration of extra beans in the context or the import of additional configuration classes. An alternative to Spring’s standard@Configuration
that aids configuration detection in your integration tests.
// Same as @SpringBootConfiguration @EnableAutoConfiguration @ComponentScan
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
// same as @SpringBootConfiguration @EnableAutoConfiguration @ComponentScan
@SpringBootApplication
class MyApplication
fun main(args: Array<String>) {
runApplication<MyApplication>(*args)
}
@SpringBootApplication also provides aliases to customize the attributes of @EnableAutoConfiguration and @ComponentScan .
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None of these features are mandatory and you may choose to replace this single annotation by any of the features that it enables. For instance, you may not want to use component scan or configuration properties scan in your application: Java
Kotlin
In this example, |
6.7. Running Your Application
One of the biggest advantages of packaging your application as a jar and using an embedded HTTP server is that you can run your application as you would any other. The sample applies to debugging Spring Boot applications. You do not need any special IDE plugins or extensions.
This section only covers jar-based packaging. If you choose to package your application as a war file, see your server and IDE documentation. |
6.7.1. Running From an IDE
You can run a Spring Boot application from your IDE as a Java application.
However, you first need to import your project.
Import steps vary depending on your IDE and build system.
Most IDEs can import Maven projects directly.
For example, Eclipse users can select Import…
→ Existing Maven Projects
from the File
menu.
If you cannot directly import your project into your IDE, you may be able to generate IDE metadata by using a build plugin. Maven includes plugins for Eclipse and IDEA. Gradle offers plugins for various IDEs.
If you accidentally run a web application twice, you see a “Port already in use” error.
Spring Tools users can use the Relaunch button rather than the Run button to ensure that any existing instance is closed.
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6.7.2. Running as a Packaged Application
If you use the Spring Boot Maven or Gradle plugins to create an executable jar, you can run your application using java -jar
, as shown in the following example:
$ java -jar target/myapplication-0.0.1-SNAPSHOT.jar
It is also possible to run a packaged application with remote debugging support enabled. Doing so lets you attach a debugger to your packaged application, as shown in the following example:
$ java -Xdebug -Xrunjdwp:server=y,transport=dt_socket,address=8000,suspend=n \
-jar target/myapplication-0.0.1-SNAPSHOT.jar
6.7.3. Using the Maven Plugin
The Spring Boot Maven plugin includes a run
goal that can be used to quickly compile and run your application.
Applications run in an exploded form, as they do in your IDE.
The following example shows a typical Maven command to run a Spring Boot application:
$ mvn spring-boot:run
You might also want to use the MAVEN_OPTS
operating system environment variable, as shown in the following example:
$ export MAVEN_OPTS=-Xmx1024m
6.7.4. Using the Gradle Plugin
The Spring Boot Gradle plugin also includes a bootRun
task that can be used to run your application in an exploded form.
The bootRun
task is added whenever you apply the org.springframework.boot
and java
plugins and is shown in the following example:
$ gradle bootRun
You might also want to use the JAVA_OPTS
operating system environment variable, as shown in the following example:
$ export JAVA_OPTS=-Xmx1024m
6.7.5. Hot Swapping
Since Spring Boot applications are plain Java applications, JVM hot-swapping should work out of the box. JVM hot swapping is somewhat limited with the bytecode that it can replace. For a more complete solution, JRebel can be used.
The spring-boot-devtools
module also includes support for quick application restarts.
See the Hot swapping “How-to” for details.
6.8. Developer Tools
Spring Boot includes an additional set of tools that can make the application development experience a little more pleasant.
The spring-boot-devtools
module can be included in any project to provide additional development-time features.
To include devtools support, add the module dependency to your build, as shown in the following listings for Maven and Gradle:
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
</dependencies>
dependencies {
developmentOnly("org.springframework.boot:spring-boot-devtools")
}
Devtools might cause classloading issues, in particular in multi-module projects. Diagnosing Classloading Issues explains how to diagnose and solve them. |
Developer tools are automatically disabled when running a fully packaged application.
If your application is launched from java -jar or if it is started from a special classloader, then it is considered a “production application”.
You can control this behavior by using the spring.devtools.restart.enabled system property.
To enable devtools, irrespective of the classloader used to launch your application, set the -Dspring.devtools.restart.enabled=true system property.
This must not be done in a production environment where running devtools is a security risk.
To disable devtools, exclude the dependency or set the -Dspring.devtools.restart.enabled=false system property.
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Flagging the dependency as optional in Maven or using the developmentOnly configuration in Gradle (as shown above) prevents devtools from being transitively applied to other modules that use your project.
|
Repackaged archives do not contain devtools by default.
If you want to use a certain remote devtools feature, you need to include it.
When using the Maven plugin, set the excludeDevtools property to false .
When using the Gradle plugin, configure the task’s classpath to include the developmentOnly configuration.
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6.8.1. Diagnosing Classloading Issues
As described in the Restart vs Reload section, restart functionality is implemented by using two classloaders. For most applications, this approach works well. However, it can sometimes cause classloading issues, in particular in multi-module projects.
To diagnose whether the classloading issues are indeed caused by devtools and its two classloaders, try disabling restart. If this solves your problems, customize the restart classloader to include your entire project.
6.8.2. Property Defaults
Several of the libraries supported by Spring Boot use caches to improve performance. For example, template engines cache compiled templates to avoid repeatedly parsing template files. Also, Spring MVC can add HTTP caching headers to responses when serving static resources.
While caching is very beneficial in production, it can be counter-productive during development, preventing you from seeing the changes you just made in your application. For this reason, spring-boot-devtools disables the caching options by default.
Cache options are usually configured by settings in your application.properties
file.
For example, Thymeleaf offers the spring.thymeleaf.cache
property.
Rather than needing to set these properties manually, the spring-boot-devtools
module automatically applies sensible development-time configuration.
The following table lists all the properties that are applied:
Name | Default Value |
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If you do not want property defaults to be applied you can set spring.devtools.add-properties to false in your application.properties .
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Because you need more information about web requests while developing Spring MVC and Spring WebFlux applications, developer tools suggests you to enable DEBUG
logging for the web
logging group.
This will give you information about the incoming request, which handler is processing it, the response outcome, and other details.
If you wish to log all request details (including potentially sensitive information), you can turn on the spring.mvc.log-request-details
or spring.codec.log-request-details
configuration properties.
6.8.3. Automatic Restart
Applications that use spring-boot-devtools
automatically restart whenever files on the classpath change.
This can be a useful feature when working in an IDE, as it gives a very fast feedback loop for code changes.
By default, any entry on the classpath that points to a directory is monitored for changes.
Note that certain resources, such as static assets and view templates, do not need to restart the application.
If you are restarting with Maven or Gradle using the build plugin you must leave the forking set to enabled .
If you disable forking, the isolated application classloader used by devtools will not be created and restarts will not operate properly.
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Automatic restart works very well when used with LiveReload. See the LiveReload section for details. If you use JRebel, automatic restarts are disabled in favor of dynamic class reloading. Other devtools features (such as LiveReload and property overrides) can still be used. |
DevTools relies on the application context’s shutdown hook to close it during a restart.
It does not work correctly if you have disabled the shutdown hook (SpringApplication.setRegisterShutdownHook(false) ).
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DevTools needs to customize the ResourceLoader used by the ApplicationContext .
If your application provides one already, it is going to be wrapped.
Direct override of the getResource method on the ApplicationContext is not supported.
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Automatic restart is not supported when using AspectJ weaving. |
Logging Changes in Condition Evaluation
By default, each time your application restarts, a report showing the condition evaluation delta is logged. The report shows the changes to your application’s auto-configuration as you make changes such as adding or removing beans and setting configuration properties.
To disable the logging of the report, set the following property:
spring.devtools.restart.log-condition-evaluation-delta=false
spring:
devtools:
restart:
log-condition-evaluation-delta: false
Excluding Resources
Certain resources do not necessarily need to trigger a restart when they are changed.
For example, Thymeleaf templates can be edited in-place.
By default, changing resources in /META-INF/maven
, /META-INF/resources
, /resources
, /static
, /public
, or /templates
does not trigger a restart but does trigger a live reload.
If you want to customize these exclusions, you can use the spring.devtools.restart.exclude
property.
For example, to exclude only /static
and /public
you would set the following property:
spring.devtools.restart.exclude=static/**,public/**
spring:
devtools:
restart:
exclude: "static/**,public/**"
If you want to keep those defaults and add additional exclusions, use the spring.devtools.restart.additional-exclude property instead.
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Watching Additional Paths
You may want your application to be restarted or reloaded when you make changes to files that are not on the classpath.
To do so, use the spring.devtools.restart.additional-paths
property to configure additional paths to watch for changes.
You can use the spring.devtools.restart.exclude
property described earlier to control whether changes beneath the additional paths trigger a full restart or a live reload.
Disabling Restart
If you do not want to use the restart feature, you can disable it by using the spring.devtools.restart.enabled
property.
In most cases, you can set this property in your application.properties
(doing so still initializes the restart classloader, but it does not watch for file changes).
If you need to completely disable restart support (for example, because it does not work with a specific library), you need to set the spring.devtools.restart.enabled
System
property to false
before calling SpringApplication.run(…)
, as shown in the following example:
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
System.setProperty("spring.devtools.restart.enabled", "false");
SpringApplication.run(MyApplication.class, args);
}
}
@SpringBootApplication
object MyApplication {
@JvmStatic
fun main(args: Array<String>) {
System.setProperty("spring.devtools.restart.enabled", "false")
SpringApplication.run(MyApplication::class.java, *args)
}
}
Using a Trigger File
If you work with an IDE that continuously compiles changed files, you might prefer to trigger restarts only at specific times. To do so, you can use a “trigger file”, which is a special file that must be modified when you want to actually trigger a restart check.
Any update to the file will trigger a check, but restart only actually occurs if Devtools has detected it has something to do. |
To use a trigger file, set the spring.devtools.restart.trigger-file
property to the name (excluding any path) of your trigger file.
The trigger file must appear somewhere on your classpath.
For example, if you have a project with the following structure:
src +- main +- resources +- .reloadtrigger
Then your trigger-file
property would be:
spring.devtools.restart.trigger-file=.reloadtrigger
spring:
devtools:
restart:
trigger-file: ".reloadtrigger"
Restarts will now only happen when the src/main/resources/.reloadtrigger
is updated.
You might want to set spring.devtools.restart.trigger-file as a global setting, so that all your projects behave in the same way.
|
Some IDEs have features that save you from needing to update your trigger file manually.
Spring Tools for Eclipse and IntelliJ IDEA (Ultimate Edition) both have such support.
With Spring Tools, you can use the “reload” button from the console view (as long as your trigger-file
is named .reloadtrigger
).
For IntelliJ IDEA, you can follow the instructions in their documentation.
Customizing the Restart Classloader
As described earlier in the Restart vs Reload section, restart functionality is implemented by using two classloaders. If this causes issues, you might need to customize what gets loaded by which classloader.
By default, any open project in your IDE is loaded with the “restart” classloader, and any regular .jar
file is loaded with the “base” classloader.
The same is true if you use mvn spring-boot:run
or gradle bootRun
: the project containing your @SpringBootApplication
is loaded with the “restart” classloader, and everything else with the “base” classloader.
You can instruct Spring Boot to load parts of your project with a different classloader by creating a META-INF/spring-devtools.properties
file.
The spring-devtools.properties
file can contain properties prefixed with restart.exclude
and restart.include
.
The include
elements are items that should be pulled up into the “restart” classloader, and the exclude
elements are items that should be pushed down into the “base” classloader.
The value of the property is a regex pattern that is applied to the classpath, as shown in the following example:
restart.exclude.companycommonlibs=/mycorp-common-[\\w\\d-\\.]+\\.jar
restart.include.projectcommon=/mycorp-myproj-[\\w\\d-\\.]+\\.jar
restart:
exclude:
companycommonlibs: "/mycorp-common-[\\w\\d-\\.]+\\.jar"
include:
projectcommon: "/mycorp-myproj-[\\w\\d-\\.]+\\.jar"
All property keys must be unique.
As long as a property starts with restart.include. or restart.exclude. it is considered.
|
All META-INF/spring-devtools.properties from the classpath are loaded.
You can package files inside your project, or in the libraries that the project consumes.
|
Known Limitations
Restart functionality does not work well with objects that are deserialized by using a standard ObjectInputStream
.
If you need to deserialize data, you may need to use Spring’s ConfigurableObjectInputStream
in combination with Thread.currentThread().getContextClassLoader()
.
Unfortunately, several third-party libraries deserialize without considering the context classloader. If you find such a problem, you need to request a fix with the original authors.
6.8.4. LiveReload
The spring-boot-devtools
module includes an embedded LiveReload server that can be used to trigger a browser refresh when a resource is changed.
LiveReload browser extensions are freely available for Chrome, Firefox and Safari.
You can find these extensions by searching 'LiveReload' in the marketplace or store of your chosen browser.
If you do not want to start the LiveReload server when your application runs, you can set the spring.devtools.livereload.enabled
property to false
.
You can only run one LiveReload server at a time. Before starting your application, ensure that no other LiveReload servers are running. If you start multiple applications from your IDE, only the first has LiveReload support. |
To trigger LiveReload when a file changes, Automatic Restart must be enabled. |
6.8.5. Global Settings
You can configure global devtools settings by adding any of the following files to the $HOME/.config/spring-boot
directory:
-
spring-boot-devtools.properties
-
spring-boot-devtools.yaml
-
spring-boot-devtools.yml
Any properties added to these files apply to all Spring Boot applications on your machine that use devtools.
For example, to configure restart to always use a trigger file, you would add the following property to your spring-boot-devtools
file:
spring.devtools.restart.trigger-file=.reloadtrigger
spring:
devtools:
restart:
trigger-file: ".reloadtrigger"
By default, $HOME
is the user’s home directory.
To customize this location, set the SPRING_DEVTOOLS_HOME
environment variable or the spring.devtools.home
system property.
If devtools configuration files are not found in $HOME/.config/spring-boot , the root of the $HOME directory is searched for the presence of a .spring-boot-devtools.properties file.
This allows you to share the devtools global configuration with applications that are on an older version of Spring Boot that does not support the $HOME/.config/spring-boot location.
|
Profiles are not supported in devtools properties/yaml files. Any profiles activated in |
Configuring File System Watcher
FileSystemWatcher works by polling the class changes with a certain time interval, and then waiting for a predefined quiet period to make sure there are no more changes.
Since Spring Boot relies entirely on the IDE to compile and copy files into the location from where Spring Boot can read them, you might find that there are times when certain changes are not reflected when devtools restarts the application.
If you observe such problems constantly, try increasing the spring.devtools.restart.poll-interval
and spring.devtools.restart.quiet-period
parameters to the values that fit your development environment:
spring.devtools.restart.poll-interval=2s
spring.devtools.restart.quiet-period=1s
spring:
devtools:
restart:
poll-interval: "2s"
quiet-period: "1s"
The monitored classpath directories are now polled every 2 seconds for changes, and a 1 second quiet period is maintained to make sure there are no additional class changes.
6.8.6. Remote Applications
The Spring Boot developer tools are not limited to local development. You can also use several features when running applications remotely. Remote support is opt-in as enabling it can be a security risk. It should only be enabled when running on a trusted network or when secured with SSL. If neither of these options is available to you, you should not use DevTools' remote support. You should never enable support on a production deployment.
To enable it, you need to make sure that devtools
is included in the repackaged archive, as shown in the following listing:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<excludeDevtools>false</excludeDevtools>
</configuration>
</plugin>
</plugins>
</build>
Then you need to set the spring.devtools.remote.secret
property.
Like any important password or secret, the value should be unique and strong such that it cannot be guessed or brute-forced.
Remote devtools support is provided in two parts: a server-side endpoint that accepts connections and a client application that you run in your IDE.
The server component is automatically enabled when the spring.devtools.remote.secret
property is set.
The client component must be launched manually.
Remote devtools is not supported for Spring WebFlux applications. |
Running the Remote Client Application
The remote client application is designed to be run from within your IDE.
You need to run org.springframework.boot.devtools.RemoteSpringApplication
with the same classpath as the remote project that you connect to.
The application’s single required argument is the remote URL to which it connects.
For example, if you are using Eclipse or Spring Tools and you have a project named my-app
that you have deployed to Cloud Foundry, you would do the following:
-
Select
Run Configurations…
from theRun
menu. -
Create a new
Java Application
“launch configuration”. -
Browse for the
my-app
project. -
Use
org.springframework.boot.devtools.RemoteSpringApplication
as the main class. -
Add
https://myapp.cfapps.io
to theProgram arguments
(or whatever your remote URL is).
A running remote client might resemble the following listing:
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ ___ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | | _ \___ _ __ ___| |_ ___ \ \ \ \ \\/ ___)| |_)| | | | | || (_| []::::::[] / -_) ' \/ _ \ _/ -_) ) ) ) ) ' |____| .__|_| |_|_| |_\__, | |_|_\___|_|_|_\___/\__\___|/ / / / =========|_|==============|___/===================================/_/_/_/ :: Spring Boot Remote :: (v3.2.0-SNAPSHOT) 2023-11-23T12:27:35.881Z INFO 37251 --- [ main] o.s.b.devtools.RemoteSpringApplication : Starting RemoteSpringApplication v3.2.0-SNAPSHOT using Java 17.0.9 with PID 37251 (/Users/myuser/.m2/repository/org/springframework/boot/spring-boot-devtools/3.2.0-SNAPSHOT/spring-boot-devtools-3.2.0-SNAPSHOT.jar started by myuser in /opt/apps/) 2023-11-23T12:27:35.892Z INFO 37251 --- [ main] o.s.b.devtools.RemoteSpringApplication : No active profile set, falling back to 1 default profile: "default" 2023-11-23T12:27:36.402Z INFO 37251 --- [ main] o.s.b.d.a.OptionalLiveReloadServer : LiveReload server is running on port 35729 2023-11-23T12:27:36.455Z INFO 37251 --- [ main] o.s.b.devtools.RemoteSpringApplication : Started RemoteSpringApplication in 1.238 seconds (process running for 2.068)
Because the remote client is using the same classpath as the real application it can directly read application properties.
This is how the spring.devtools.remote.secret property is read and passed to the server for authentication.
|
It is always advisable to use https:// as the connection protocol, so that traffic is encrypted and passwords cannot be intercepted.
|
If you need to use a proxy to access the remote application, configure the spring.devtools.remote.proxy.host and spring.devtools.remote.proxy.port properties.
|
Remote Update
The remote client monitors your application classpath for changes in the same way as the local restart. Any updated resource is pushed to the remote application and (if required) triggers a restart. This can be helpful if you iterate on a feature that uses a cloud service that you do not have locally. Generally, remote updates and restarts are much quicker than a full rebuild and deploy cycle.
On a slower development environment, it may happen that the quiet period is not enough, and the changes in the classes may be split into batches. The server is restarted after the first batch of class changes is uploaded. The next batch can’t be sent to the application, since the server is restarting.
This is typically manifested by a warning in the RemoteSpringApplication
logs about failing to upload some of the classes, and a consequent retry.
But it may also lead to application code inconsistency and failure to restart after the first batch of changes is uploaded.
If you observe such problems constantly, try increasing the spring.devtools.restart.poll-interval
and spring.devtools.restart.quiet-period
parameters to the values that fit your development environment.
See the Configuring File System Watcher section for configuring these properties.
Files are only monitored when the remote client is running. If you change a file before starting the remote client, it is not pushed to the remote server. |
6.9. Packaging Your Application for Production
Executable jars can be used for production deployment. As they are self-contained, they are also ideally suited for cloud-based deployment.
For additional “production ready” features, such as health, auditing, and metric REST or JMX end-points, consider adding spring-boot-actuator
.
See Production-ready Features for details.
6.10. What to Read Next
You should now understand how you can use Spring Boot and some best practices that you should follow. You can now go on to learn about specific Spring Boot features in depth, or you could skip ahead and read about the “production ready” aspects of Spring Boot.
7. Core Features
This section dives into the details of Spring Boot. Here you can learn about the key features that you may want to use and customize. If you have not already done so, you might want to read the "Getting Started" and "Developing with Spring Boot" sections, so that you have a good grounding of the basics.
7.1. SpringApplication
The SpringApplication
class provides a convenient way to bootstrap a Spring application that is started from a main()
method.
In many situations, you can delegate to the static SpringApplication.run
method, as shown in the following example:
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
@SpringBootApplication
class MyApplication
fun main(args: Array<String>) {
runApplication<MyApplication>(*args)
}
When your application starts, you should see something similar to the following output:
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v3.2.0-SNAPSHOT) 2023-11-23T12:27:37.787Z INFO 37333 --- [ main] o.s.b.d.f.logexample.MyApplication : Starting MyApplication using Java 17.0.9 with PID 37333 (/opt/apps/myapp.jar started by myuser in /opt/apps/) 2023-11-23T12:27:37.796Z INFO 37333 --- [ main] o.s.b.d.f.logexample.MyApplication : No active profile set, falling back to 1 default profile: "default" 2023-11-23T12:27:39.649Z INFO 37333 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port 8080 (http) 2023-11-23T12:27:39.666Z INFO 37333 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2023-11-23T12:27:39.666Z INFO 37333 --- [ main] o.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/10.1.16] 2023-11-23T12:27:39.755Z INFO 37333 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2023-11-23T12:27:39.758Z INFO 37333 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1850 ms 2023-11-23T12:27:40.486Z INFO 37333 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port 8080 (http) with context path '' 2023-11-23T12:27:40.499Z INFO 37333 --- [ main] o.s.b.d.f.logexample.MyApplication : Started MyApplication in 3.44 seconds (process running for 4.02)
By default, INFO
logging messages are shown, including some relevant startup details, such as the user that launched the application.
If you need a log level other than INFO
, you can set it, as described in Log Levels.
The application version is determined using the implementation version from the main application class’s package.
Startup information logging can be turned off by setting spring.main.log-startup-info
to false
.
This will also turn off logging of the application’s active profiles.
To add additional logging during startup, you can override logStartupInfo(boolean) in a subclass of SpringApplication .
|
7.1.1. Startup Failure
If your application fails to start, registered FailureAnalyzers
get a chance to provide a dedicated error message and a concrete action to fix the problem.
For instance, if you start a web application on port 8080
and that port is already in use, you should see something similar to the following message:
*************************** APPLICATION FAILED TO START *************************** Description: Embedded servlet container failed to start. Port 8080 was already in use. Action: Identify and stop the process that is listening on port 8080 or configure this application to listen on another port.
Spring Boot provides numerous FailureAnalyzer implementations, and you can add your own.
|
If no failure analyzers are able to handle the exception, you can still display the full conditions report to better understand what went wrong.
To do so, you need to enable the debug
property or enable DEBUG
logging for org.springframework.boot.autoconfigure.logging.ConditionEvaluationReportLoggingListener
.
For instance, if you are running your application by using java -jar
, you can enable the debug
property as follows:
$ java -jar myproject-0.0.1-SNAPSHOT.jar --debug
7.1.2. Lazy Initialization
SpringApplication
allows an application to be initialized lazily.
When lazy initialization is enabled, beans are created as they are needed rather than during application startup.
As a result, enabling lazy initialization can reduce the time that it takes your application to start.
In a web application, enabling lazy initialization will result in many web-related beans not being initialized until an HTTP request is received.
A downside of lazy initialization is that it can delay the discovery of a problem with the application. If a misconfigured bean is initialized lazily, a failure will no longer occur during startup and the problem will only become apparent when the bean is initialized. Care must also be taken to ensure that the JVM has sufficient memory to accommodate all of the application’s beans and not just those that are initialized during startup. For these reasons, lazy initialization is not enabled by default and it is recommended that fine-tuning of the JVM’s heap size is done before enabling lazy initialization.
Lazy initialization can be enabled programmatically using the lazyInitialization
method on SpringApplicationBuilder
or the setLazyInitialization
method on SpringApplication
.
Alternatively, it can be enabled using the spring.main.lazy-initialization
property as shown in the following example:
spring.main.lazy-initialization=true
spring:
main:
lazy-initialization: true
If you want to disable lazy initialization for certain beans while using lazy initialization for the rest of the application, you can explicitly set their lazy attribute to false using the @Lazy(false) annotation.
|
7.1.3. Customizing the Banner
The banner that is printed on start up can be changed by adding a banner.txt
file to your classpath or by setting the spring.banner.location
property to the location of such a file.
If the file has an encoding other than UTF-8, you can set spring.banner.charset
.
Inside your banner.txt
file, you can use any key available in the Environment
as well as any of the following placeholders:
Variable | Description |
---|---|
|
The version number of your application, as declared in |
|
The version number of your application, as declared in |
|
The Spring Boot version that you are using.
For example |
|
The Spring Boot version that you are using, formatted for display (surrounded with brackets and prefixed with |
|
Where |
|
The title of your application, as declared in |
The SpringApplication.setBanner(…) method can be used if you want to generate a banner programmatically.
Use the org.springframework.boot.Banner interface and implement your own printBanner() method.
|
You can also use the spring.main.banner-mode
property to determine if the banner has to be printed on System.out
(console
), sent to the configured logger (log
), or not produced at all (off
).
The printed banner is registered as a singleton bean under the following name: springBootBanner
.
The To use the |
7.1.4. Customizing SpringApplication
If the SpringApplication
defaults are not to your taste, you can instead create a local instance and customize it.
For example, to turn off the banner, you could write:
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
SpringApplication application = new SpringApplication(MyApplication.class);
application.setBannerMode(Banner.Mode.OFF);
application.run(args);
}
}
@SpringBootApplication
class MyApplication
fun main(args: Array<String>) {
runApplication<MyApplication>(*args) {
setBannerMode(Banner.Mode.OFF)
}
}
The constructor arguments passed to SpringApplication are configuration sources for Spring beans.
In most cases, these are references to @Configuration classes, but they could also be direct references @Component classes.
|
It is also possible to configure the SpringApplication
by using an application.properties
file.
See Externalized Configuration for details.
For a complete list of the configuration options, see the SpringApplication
Javadoc.
7.1.5. Fluent Builder API
If you need to build an ApplicationContext
hierarchy (multiple contexts with a parent/child relationship) or if you prefer using a “fluent” builder API, you can use the SpringApplicationBuilder
.
The SpringApplicationBuilder
lets you chain together multiple method calls and includes parent
and child
methods that let you create a hierarchy, as shown in the following example:
new SpringApplicationBuilder().sources(Parent.class)
.child(Application.class)
.bannerMode(Banner.Mode.OFF)
.run(args);
SpringApplicationBuilder()
.sources(Parent::class.java)
.child(Application::class.java)
.bannerMode(Banner.Mode.OFF)
.run(*args)
There are some restrictions when creating an ApplicationContext hierarchy.
For example, Web components must be contained within the child context, and the same Environment is used for both parent and child contexts.
See the SpringApplicationBuilder Javadoc for full details.
|
7.1.6. Application Availability
When deployed on platforms, applications can provide information about their availability to the platform using infrastructure such as Kubernetes Probes. Spring Boot includes out-of-the box support for the commonly used “liveness” and “readiness” availability states. If you are using Spring Boot’s “actuator” support then these states are exposed as health endpoint groups.
In addition, you can also obtain availability states by injecting the ApplicationAvailability
interface into your own beans.
Liveness State
The “Liveness” state of an application tells whether its internal state allows it to work correctly, or recover by itself if it is currently failing. A broken “Liveness” state means that the application is in a state that it cannot recover from, and the infrastructure should restart the application.
In general, the "Liveness" state should not be based on external checks, such as Health checks. If it did, a failing external system (a database, a Web API, an external cache) would trigger massive restarts and cascading failures across the platform. |
The internal state of Spring Boot applications is mostly represented by the Spring ApplicationContext
.
If the application context has started successfully, Spring Boot assumes that the application is in a valid state.
An application is considered live as soon as the context has been refreshed, see Spring Boot application lifecycle and related Application Events.
Readiness State
The “Readiness” state of an application tells whether the application is ready to handle traffic.
A failing “Readiness” state tells the platform that it should not route traffic to the application for now.
This typically happens during startup, while CommandLineRunner
and ApplicationRunner
components are being processed, or at any time if the application decides that it is too busy for additional traffic.
An application is considered ready as soon as application and command-line runners have been called, see Spring Boot application lifecycle and related Application Events.
Tasks expected to run during startup should be executed by CommandLineRunner and ApplicationRunner components instead of using Spring component lifecycle callbacks such as @PostConstruct .
|
Managing the Application Availability State
Application components can retrieve the current availability state at any time, by injecting the ApplicationAvailability
interface and calling methods on it.
More often, applications will want to listen to state updates or update the state of the application.
For example, we can export the "Readiness" state of the application to a file so that a Kubernetes "exec Probe" can look at this file:
@Component
public class MyReadinessStateExporter {
@EventListener
public void onStateChange(AvailabilityChangeEvent<ReadinessState> event) {
switch (event.getState()) {
case ACCEPTING_TRAFFIC -> {
// create file /tmp/healthy
}
case REFUSING_TRAFFIC -> {
// remove file /tmp/healthy
}
}
}
}
@Component
class MyReadinessStateExporter {
@EventListener
fun onStateChange(event: AvailabilityChangeEvent<ReadinessState?>) {
when (event.state) {
ReadinessState.ACCEPTING_TRAFFIC -> {
// create file /tmp/healthy
}
ReadinessState.REFUSING_TRAFFIC -> {
// remove file /tmp/healthy
}
else -> {
// ...
}
}
}
}
We can also update the state of the application, when the application breaks and cannot recover:
@Component
public class MyLocalCacheVerifier {
private final ApplicationEventPublisher eventPublisher;
public MyLocalCacheVerifier(ApplicationEventPublisher eventPublisher) {
this.eventPublisher = eventPublisher;
}
public void checkLocalCache() {
try {
// ...
}
catch (CacheCompletelyBrokenException ex) {
AvailabilityChangeEvent.publish(this.eventPublisher, ex, LivenessState.BROKEN);
}
}
}
@Component
class MyLocalCacheVerifier(private val eventPublisher: ApplicationEventPublisher) {
fun checkLocalCache() {
try {
// ...
} catch (ex: CacheCompletelyBrokenException) {
AvailabilityChangeEvent.publish(eventPublisher, ex, LivenessState.BROKEN)
}
}
}
Spring Boot provides Kubernetes HTTP probes for "Liveness" and "Readiness" with Actuator Health Endpoints. You can get more guidance about deploying Spring Boot applications on Kubernetes in the dedicated section.
7.1.7. Application Events and Listeners
In addition to the usual Spring Framework events, such as ContextRefreshedEvent
, a SpringApplication
sends some additional application events.
Some events are actually triggered before the If you want those listeners to be registered automatically, regardless of the way the application is created, you can add a org.springframework.context.ApplicationListener=com.example.project.MyListener |
Application events are sent in the following order, as your application runs:
-
An
ApplicationStartingEvent
is sent at the start of a run but before any processing, except for the registration of listeners and initializers. -
An
ApplicationEnvironmentPreparedEvent
is sent when theEnvironment
to be used in the context is known but before the context is created. -
An
ApplicationContextInitializedEvent
is sent when theApplicationContext
is prepared and ApplicationContextInitializers have been called but before any bean definitions are loaded. -
An
ApplicationPreparedEvent
is sent just before the refresh is started but after bean definitions have been loaded. -
An
ApplicationStartedEvent
is sent after the context has been refreshed but before any application and command-line runners have been called. -
An
AvailabilityChangeEvent
is sent right after withLivenessState.CORRECT
to indicate that the application is considered as live. -
An
ApplicationReadyEvent
is sent after any application and command-line runners have been called. -
An
AvailabilityChangeEvent
is sent right after withReadinessState.ACCEPTING_TRAFFIC
to indicate that the application is ready to service requests. -
An
ApplicationFailedEvent
is sent if there is an exception on startup.
The above list only includes SpringApplicationEvent
s that are tied to a SpringApplication
.
In addition to these, the following events are also published after ApplicationPreparedEvent
and before ApplicationStartedEvent
:
-
A
WebServerInitializedEvent
is sent after theWebServer
is ready.ServletWebServerInitializedEvent
andReactiveWebServerInitializedEvent
are the servlet and reactive variants respectively. -
A
ContextRefreshedEvent
is sent when anApplicationContext
is refreshed.
You often need not use application events, but it can be handy to know that they exist. Internally, Spring Boot uses events to handle a variety of tasks. |
Event listeners should not run potentially lengthy tasks as they execute in the same thread by default. Consider using application and command-line runners instead. |
Application events are sent by using Spring Framework’s event publishing mechanism.
Part of this mechanism ensures that an event published to the listeners in a child context is also published to the listeners in any ancestor contexts.
As a result of this, if your application uses a hierarchy of SpringApplication
instances, a listener may receive multiple instances of the same type of application event.
To allow your listener to distinguish between an event for its context and an event for a descendant context, it should request that its application context is injected and then compare the injected context with the context of the event.
The context can be injected by implementing ApplicationContextAware
or, if the listener is a bean, by using @Autowired
.
7.1.8. Web Environment
A SpringApplication
attempts to create the right type of ApplicationContext
on your behalf.
The algorithm used to determine a WebApplicationType
is the following:
-
If Spring MVC is present, an
AnnotationConfigServletWebServerApplicationContext
is used -
If Spring MVC is not present and Spring WebFlux is present, an
AnnotationConfigReactiveWebServerApplicationContext
is used -
Otherwise,
AnnotationConfigApplicationContext
is used
This means that if you are using Spring MVC and the new WebClient
from Spring WebFlux in the same application, Spring MVC will be used by default.
You can override that easily by calling setWebApplicationType(WebApplicationType)
.
It is also possible to take complete control of the ApplicationContext
type that is used by calling setApplicationContextFactory(…)
.
It is often desirable to call setWebApplicationType(WebApplicationType.NONE) when using SpringApplication within a JUnit test.
|
7.1.9. Accessing Application Arguments
If you need to access the application arguments that were passed to SpringApplication.run(…)
, you can inject a org.springframework.boot.ApplicationArguments
bean.
The ApplicationArguments
interface provides access to both the raw String[]
arguments as well as parsed option
and non-option
arguments, as shown in the following example:
@Component
public class MyBean {
public MyBean(ApplicationArguments args) {
boolean debug = args.containsOption("debug");
List<String> files = args.getNonOptionArgs();
if (debug) {
System.out.println(files);
}
// if run with "--debug logfile.txt" prints ["logfile.txt"]
}
}
@Component
class MyBean(args: ApplicationArguments) {
init {
val debug = args.containsOption("debug")
val files = args.nonOptionArgs
if (debug) {
println(files)
}
// if run with "--debug logfile.txt" prints ["logfile.txt"]
}
}
Spring Boot also registers a CommandLinePropertySource with the Spring Environment .
This lets you also inject single application arguments by using the @Value annotation.
|
7.1.10. Using the ApplicationRunner or CommandLineRunner
If you need to run some specific code once the SpringApplication
has started, you can implement the ApplicationRunner
or CommandLineRunner
interfaces.
Both interfaces work in the same way and offer a single run
method, which is called just before SpringApplication.run(…)
completes.
This contract is well suited for tasks that should run after application startup but before it starts accepting traffic. |
The CommandLineRunner
interfaces provides access to application arguments as a string array, whereas the ApplicationRunner
uses the ApplicationArguments
interface discussed earlier.
The following example shows a CommandLineRunner
with a run
method:
@Component
public class MyCommandLineRunner implements CommandLineRunner {
@Override
public void run(String... args) {
// Do something...
}
}
@Component
class MyCommandLineRunner : CommandLineRunner {
override fun run(vararg args: String) {
// Do something...
}
}
If several CommandLineRunner
or ApplicationRunner
beans are defined that must be called in a specific order, you can additionally implement the org.springframework.core.Ordered
interface or use the org.springframework.core.annotation.Order
annotation.
7.1.11. Application Exit
Each SpringApplication
registers a shutdown hook with the JVM to ensure that the ApplicationContext
closes gracefully on exit.
All the standard Spring lifecycle callbacks (such as the DisposableBean
interface or the @PreDestroy
annotation) can be used.
In addition, beans may implement the org.springframework.boot.ExitCodeGenerator
interface if they wish to return a specific exit code when SpringApplication.exit()
is called.
This exit code can then be passed to System.exit()
to return it as a status code, as shown in the following example:
@SpringBootApplication
public class MyApplication {
@Bean
public ExitCodeGenerator exitCodeGenerator() {
return () -> 42;
}
public static void main(String[] args) {
System.exit(SpringApplication.exit(SpringApplication.run(MyApplication.class, args)));
}
}
@SpringBootApplication
class MyApplication {
@Bean
fun exitCodeGenerator() = ExitCodeGenerator { 42 }
}
fun main(args: Array<String>) {
exitProcess(SpringApplication.exit(
runApplication<MyApplication>(*args)))
}
Also, the ExitCodeGenerator
interface may be implemented by exceptions.
When such an exception is encountered, Spring Boot returns the exit code provided by the implemented getExitCode()
method.
If there is more than one ExitCodeGenerator
, the first non-zero exit code that is generated is used.
To control the order in which the generators are called, additionally implement the org.springframework.core.Ordered
interface or use the org.springframework.core.annotation.Order
annotation.
7.1.12. Admin Features
It is possible to enable admin-related features for the application by specifying the spring.application.admin.enabled
property.
This exposes the SpringApplicationAdminMXBean
on the platform MBeanServer
.
You could use this feature to administer your Spring Boot application remotely.
This feature could also be useful for any service wrapper implementation.
If you want to know on which HTTP port the application is running, get the property with a key of local.server.port .
|
7.1.13. Application Startup tracking
During the application startup, the SpringApplication
and the ApplicationContext
perform many tasks related to the application lifecycle,
the beans lifecycle or even processing application events.
With ApplicationStartup
, Spring Framework allows you to track the application startup sequence with StartupStep
objects.
This data can be collected for profiling purposes, or just to have a better understanding of an application startup process.
You can choose an ApplicationStartup
implementation when setting up the SpringApplication
instance.
For example, to use the BufferingApplicationStartup
, you could write:
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
SpringApplication application = new SpringApplication(MyApplication.class);
application.setApplicationStartup(new BufferingApplicationStartup(2048));
application.run(args);
}
}
@SpringBootApplication
class MyApplication
fun main(args: Array<String>) {
runApplication<MyApplication>(*args) {
applicationStartup = BufferingApplicationStartup(2048)
}
}
The first available implementation, FlightRecorderApplicationStartup
is provided by Spring Framework.
It adds Spring-specific startup events to a Java Flight Recorder session and is meant for profiling applications and correlating their Spring context lifecycle with JVM events (such as allocations, GCs, class loading…).
Once configured, you can record data by running the application with the Flight Recorder enabled:
$ java -XX:StartFlightRecording:filename=recording.jfr,duration=10s -jar demo.jar
Spring Boot ships with the BufferingApplicationStartup
variant; this implementation is meant for buffering the startup steps and draining them into an external metrics system.
Applications can ask for the bean of type BufferingApplicationStartup
in any component.
Spring Boot can also be configured to expose a startup
endpoint that provides this information as a JSON document.
7.1.14. Virtual threads
If you’re running on Java 21 or up, you can enable virtual threads by setting the property spring.threads.virtual.enabled
to true
.
One side effect of virtual threads is that these threads are daemon threads.
A JVM will exit if there are no non-daemon threads.
This behavior can be a problem when you rely on, e.g. @Scheduled beans to keep your application alive.
If you use virtual threads, the scheduler thread is a virtual thread and therefore a daemon thread and won’t keep the JVM alive.
This does not only affect scheduling, but can be the case with other technologies, too!
To keep the JVM running in all cases, it is recommended to set the property spring.main.keep-alive to true .
This ensures that the JVM is kept alive, even if all threads are virtual threads.
|
7.2. Externalized Configuration
Spring Boot lets you externalize your configuration so that you can work with the same application code in different environments. You can use a variety of external configuration sources including Java properties files, YAML files, environment variables, and command-line arguments.
Property values can be injected directly into your beans by using the @Value
annotation, accessed through Spring’s Environment
abstraction, or be bound to structured objects through @ConfigurationProperties
.
Spring Boot uses a very particular PropertySource
order that is designed to allow sensible overriding of values.
Later property sources can override the values defined in earlier ones.
Sources are considered in the following order:
-
Default properties (specified by setting
SpringApplication.setDefaultProperties
). -
@PropertySource
annotations on your@Configuration
classes. Please note that such property sources are not added to theEnvironment
until the application context is being refreshed. This is too late to configure certain properties such aslogging.*
andspring.main.*
which are read before refresh begins. -
Config data (such as
application.properties
files). -
A
RandomValuePropertySource
that has properties only inrandom.*
. -
OS environment variables.
-
Java System properties (
System.getProperties()
). -
JNDI attributes from
java:comp/env
. -
ServletContext
init parameters. -
ServletConfig
init parameters. -
Properties from
SPRING_APPLICATION_JSON
(inline JSON embedded in an environment variable or system property). -
Command line arguments.
-
properties
attribute on your tests. Available on@SpringBootTest
and the test annotations for testing a particular slice of your application. -
@DynamicPropertySource
annotations in your tests. -
@TestPropertySource
annotations on your tests. -
Devtools global settings properties in the
$HOME/.config/spring-boot
directory when devtools is active.
Config data files are considered in the following order:
-
Application properties packaged inside your jar (
application.properties
and YAML variants). -
Profile-specific application properties packaged inside your jar (
application-{profile}.properties
and YAML variants). -
Application properties outside of your packaged jar (
application.properties
and YAML variants). -
Profile-specific application properties outside of your packaged jar (
application-{profile}.properties
and YAML variants).
It is recommended to stick with one format for your entire application.
If you have configuration files with both .properties and YAML format in the same location, .properties takes precedence.
|
If you use environment variables rather than system properties, most operating systems disallow period-separated key names, but you can use underscores instead (for example, SPRING_CONFIG_NAME instead of spring.config.name ).
See Binding From Environment Variables for details.
|
If your application runs in a servlet container or application server, then JNDI properties (in java:comp/env ) or servlet context initialization parameters can be used instead of, or as well as, environment variables or system properties.
|
To provide a concrete example, suppose you develop a @Component
that uses a name
property, as shown in the following example:
@Component
public class MyBean {
@Value("${name}")
private String name;
// ...
}
@Component
class MyBean {
@Value("\${name}")
private val name: String? = null
// ...
}
On your application classpath (for example, inside your jar) you can have an application.properties
file that provides a sensible default property value for name
.
When running in a new environment, an application.properties
file can be provided outside of your jar that overrides the name
.
For one-off testing, you can launch with a specific command line switch (for example, java -jar app.jar --name="Spring"
).
The env and configprops endpoints can be useful in determining why a property has a particular value.
You can use these two endpoints to diagnose unexpected property values.
See the "Production ready features" section for details.
|
7.2.1. Accessing Command Line Properties
By default, SpringApplication
converts any command line option arguments (that is, arguments starting with --
, such as --server.port=9000
) to a property
and adds them to the Spring Environment
.
As mentioned previously, command line properties always take precedence over file-based property sources.
If you do not want command line properties to be added to the Environment
, you can disable them by using SpringApplication.setAddCommandLineProperties(false)
.
7.2.2. JSON Application Properties
Environment variables and system properties often have restrictions that mean some property names cannot be used. To help with this, Spring Boot allows you to encode a block of properties into a single JSON structure.
When your application starts, any spring.application.json
or SPRING_APPLICATION_JSON
properties will be parsed and added to the Environment
.
For example, the SPRING_APPLICATION_JSON
property can be supplied on the command line in a UN*X shell as an environment variable:
$ SPRING_APPLICATION_JSON='{"my":{"name":"test"}}' java -jar myapp.jar
In the preceding example, you end up with my.name=test
in the Spring Environment
.
The same JSON can also be provided as a system property:
$ java -Dspring.application.json='{"my":{"name":"test"}}' -jar myapp.jar
Or you could supply the JSON by using a command line argument:
$ java -jar myapp.jar --spring.application.json='{"my":{"name":"test"}}'
If you are deploying to a classic Application Server, you could also use a JNDI variable named java:comp/env/spring.application.json
.
Although null values from the JSON will be added to the resulting property source, the PropertySourcesPropertyResolver treats null properties as missing values.
This means that the JSON cannot override properties from lower order property sources with a null value.
|
7.2.3. External Application Properties
Spring Boot will automatically find and load application.properties
and application.yaml
files from the following locations when your application starts:
-
From the classpath
-
The classpath root
-
The classpath
/config
package
-
-
From the current directory
-
The current directory
-
The
config/
subdirectory in the current directory -
Immediate child directories of the
config/
subdirectory
-
The list is ordered by precedence (with values from lower items overriding earlier ones).
Documents from the loaded files are added as PropertySources
to the Spring Environment
.
If you do not like application
as the configuration file name, you can switch to another file name by specifying a spring.config.name
environment property.
For example, to look for myproject.properties
and myproject.yaml
files you can run your application as follows:
$ java -jar myproject.jar --spring.config.name=myproject
You can also refer to an explicit location by using the spring.config.location
environment property.
This property accepts a comma-separated list of one or more locations to check.
The following example shows how to specify two distinct files:
$ java -jar myproject.jar --spring.config.location=\
optional:classpath:/default.properties,\
optional:classpath:/override.properties
Use the prefix optional: if the locations are optional and you do not mind if they do not exist.
|
spring.config.name , spring.config.location , and spring.config.additional-location are used very early to determine which files have to be loaded.
They must be defined as an environment property (typically an OS environment variable, a system property, or a command-line argument).
|
If spring.config.location
contains directories (as opposed to files), they should end in /
.
At runtime they will be appended with the names generated from spring.config.name
before being loaded.
Files specified in spring.config.location
are imported directly.
Both directory and file location values are also expanded to check for profile-specific files.
For example, if you have a spring.config.location of classpath:myconfig.properties , you will also find appropriate classpath:myconfig-<profile>.properties files are loaded.
|
In most situations, each spring.config.location
item you add will reference a single file or directory.
Locations are processed in the order that they are defined and later ones can override the values of earlier ones.
If you have a complex location setup, and you use profile-specific configuration files, you may need to provide further hints so that Spring Boot knows how they should be grouped.
A location group is a collection of locations that are all considered at the same level.
For example, you might want to group all classpath locations, then all external locations.
Items within a location group should be separated with ;
.
See the example in the “Profile Specific Files” section for more details.
Locations configured by using spring.config.location
replace the default locations.
For example, if spring.config.location
is configured with the value optional:classpath:/custom-config/,optional:file:./custom-config/
, the complete set of locations considered is:
-
optional:classpath:custom-config/
-
optional:file:./custom-config/
If you prefer to add additional locations, rather than replacing them, you can use spring.config.additional-location
.
Properties loaded from additional locations can override those in the default locations.
For example, if spring.config.additional-location
is configured with the value optional:classpath:/custom-config/,optional:file:./custom-config/
, the complete set of locations considered is:
-
optional:classpath:/;optional:classpath:/config/
-
optional:file:./;optional:file:./config/;optional:file:./config/*/
-
optional:classpath:custom-config/
-
optional:file:./custom-config/
This search ordering lets you specify default values in one configuration file and then selectively override those values in another.
You can provide default values for your application in application.properties
(or whatever other basename you choose with spring.config.name
) in one of the default locations.
These default values can then be overridden at runtime with a different file located in one of the custom locations.
Optional Locations
By default, when a specified config data location does not exist, Spring Boot will throw a ConfigDataLocationNotFoundException
and your application will not start.
If you want to specify a location, but you do not mind if it does not always exist, you can use the optional:
prefix.
You can use this prefix with the spring.config.location
and spring.config.additional-location
properties, as well as with spring.config.import
declarations.
For example, a spring.config.import
value of optional:file:./myconfig.properties
allows your application to start, even if the myconfig.properties
file is missing.
If you want to ignore all ConfigDataLocationNotFoundExceptions
and always continue to start your application, you can use the spring.config.on-not-found
property.
Set the value to ignore
using SpringApplication.setDefaultProperties(…)
or with a system/environment variable.
Wildcard Locations
If a config file location includes the *
character for the last path segment, it is considered a wildcard location.
Wildcards are expanded when the config is loaded so that immediate subdirectories are also checked.
Wildcard locations are particularly useful in an environment such as Kubernetes when there are multiple sources of config properties.
For example, if you have some Redis configuration and some MySQL configuration, you might want to keep those two pieces of configuration separate, while requiring that both those are present in an application.properties
file.
This might result in two separate application.properties
files mounted at different locations such as /config/redis/application.properties
and /config/mysql/application.properties
.
In such a case, having a wildcard location of config/*/
, will result in both files being processed.
By default, Spring Boot includes config/*/
in the default search locations.
It means that all subdirectories of the /config
directory outside of your jar will be searched.
You can use wildcard locations yourself with the spring.config.location
and spring.config.additional-location
properties.
A wildcard location must contain only one * and end with */ for search locations that are directories or */<filename> for search locations that are files.
Locations with wildcards are sorted alphabetically based on the absolute path of the file names.
|
Wildcard locations only work with external directories.
You cannot use a wildcard in a classpath: location.
|
Profile Specific Files
As well as application
property files, Spring Boot will also attempt to load profile-specific files using the naming convention application-{profile}
.
For example, if your application activates a profile named prod
and uses YAML files, then both application.yaml
and application-prod.yaml
will be considered.
Profile-specific properties are loaded from the same locations as standard application.properties
, with profile-specific files always overriding the non-specific ones.
If several profiles are specified, a last-wins strategy applies.
For example, if profiles prod,live
are specified by the spring.profiles.active
property, values in application-prod.properties
can be overridden by those in application-live.properties
.
The last-wins strategy applies at the location group level.
A For example, continuing our /cfg application-live.properties /ext application-live.properties application-prod.properties When we have a
When we have
|
The Environment
has a set of default profiles (by default, [default]
) that are used if no active profiles are set.
In other words, if no profiles are explicitly activated, then properties from application-default
are considered.
Properties files are only ever loaded once. If you have already directly imported a profile specific property files then it will not be imported a second time. |
Importing Additional Data
Application properties may import further config data from other locations using the spring.config.import
property.
Imports are processed as they are discovered, and are treated as additional documents inserted immediately below the one that declares the import.
For example, you might have the following in your classpath application.properties
file:
spring.application.name=myapp
spring.config.import=optional:file:./dev.properties
spring:
application:
name: "myapp"
config:
import: "optional:file:./dev.properties"
This will trigger the import of a dev.properties
file in current directory (if such a file exists).
Values from the imported dev.properties
will take precedence over the file that triggered the import.
In the above example, the dev.properties
could redefine spring.application.name
to a different value.
An import will only be imported once no matter how many times it is declared. The order an import is defined inside a single document within the properties/yaml file does not matter. For instance, the two examples below produce the same result:
spring.config.import=my.properties
my.property=value
spring:
config:
import: "my.properties"
my:
property: "value"
my.property=value
spring.config.import=my.properties
my:
property: "value"
spring:
config:
import: "my.properties"
In both of the above examples, the values from the my.properties
file will take precedence over the file that triggered its import.
Several locations can be specified under a single spring.config.import
key.
Locations will be processed in the order that they are defined, with later imports taking precedence.
When appropriate, Profile-specific variants are also considered for import.
The example above would import both my.properties as well as any my-<profile>.properties variants.
|
Spring Boot includes pluggable API that allows various different location addresses to be supported. By default you can import Java Properties, YAML and “configuration trees”. Third-party jars can offer support for additional technologies (there is no requirement for files to be local). For example, you can imagine config data being from external stores such as Consul, Apache ZooKeeper or Netflix Archaius. If you want to support your own locations, see the |
Importing Extensionless Files
Some cloud platforms cannot add a file extension to volume mounted files. To import these extensionless files, you need to give Spring Boot a hint so that it knows how to load them. You can do this by putting an extension hint in square brackets.
For example, suppose you have a /etc/config/myconfig
file that you wish to import as yaml.
You can import it from your application.properties
using the following:
spring.config.import=file:/etc/config/myconfig[.yaml]
spring:
config:
import: "file:/etc/config/myconfig[.yaml]"
Using Configuration Trees
When running applications on a cloud platform (such as Kubernetes) you often need to read config values that the platform supplies. It is not uncommon to use environment variables for such purposes, but this can have drawbacks, especially if the value is supposed to be kept secret.
As an alternative to environment variables, many cloud platforms now allow you to map configuration into mounted data volumes.
For example, Kubernetes can volume mount both ConfigMaps
and Secrets
.
There are two common volume mount patterns that can be used:
-
A single file contains a complete set of properties (usually written as YAML).
-
Multiple files are written to a directory tree, with the filename becoming the ‘key’ and the contents becoming the ‘value’.
For the first case, you can import the YAML or Properties file directly using spring.config.import
as described above.
For the second case, you need to use the configtree:
prefix so that Spring Boot knows it needs to expose all the files as properties.
As an example, let’s imagine that Kubernetes has mounted the following volume:
etc/ config/ myapp/ username password
The contents of the username
file would be a config value, and the contents of password
would be a secret.
To import these properties, you can add the following to your application.properties
or application.yaml
file:
spring.config.import=optional:configtree:/etc/config/
spring:
config:
import: "optional:configtree:/etc/config/"
You can then access or inject myapp.username
and myapp.password
properties from the Environment
in the usual way.
The names of the folders and files under the config tree form the property name.
In the above example, to access the properties as username and password , you can set spring.config.import to optional:configtree:/etc/config/myapp .
|
Filenames with dot notation are also correctly mapped.
For example, in the above example, a file named myapp.username in /etc/config would result in a myapp.username property in the Environment .
|
Configuration tree values can be bound to both string String and byte[] types depending on the contents expected.
|
If you have multiple config trees to import from the same parent folder you can use a wildcard shortcut.
Any configtree:
location that ends with /*/
will import all immediate children as config trees.
As with a non-wildcard import, the names of the folders and files under each config tree form the property name.
For example, given the following volume:
etc/ config/ dbconfig/ db/ username password mqconfig/ mq/ username password
You can use configtree:/etc/config/*/
as the import location:
spring.config.import=optional:configtree:/etc/config/*/
spring:
config:
import: "optional:configtree:/etc/config/*/"
This will add db.username
, db.password
, mq.username
and mq.password
properties.
Directories loaded using a wildcard are sorted alphabetically. If you need a different order, then you should list each location as a separate import |
Configuration trees can also be used for Docker secrets.
When a Docker swarm service is granted access to a secret, the secret gets mounted into the container.
For example, if a secret named db.password
is mounted at location /run/secrets/
, you can make db.password
available to the Spring environment using the following:
spring.config.import=optional:configtree:/run/secrets/
spring:
config:
import: "optional:configtree:/run/secrets/"
Property Placeholders
The values in application.properties
and application.yaml
are filtered through the existing Environment
when they are used, so you can refer back to previously defined values (for example, from System properties or environment variables).
The standard ${name}
property-placeholder syntax can be used anywhere within a value.
Property placeholders can also specify a default value using a :
to separate the default value from the property name, for example ${name:default}
.
The use of placeholders with and without defaults is shown in the following example:
app.name=MyApp
app.description=${app.name} is a Spring Boot application written by ${username:Unknown}
app:
name: "MyApp"
description: "${app.name} is a Spring Boot application written by ${username:Unknown}"
Assuming that the username
property has not been set elsewhere, app.description
will have the value MyApp is a Spring Boot application written by Unknown
.
You should always refer to property names in the placeholder using their canonical form (kebab-case using only lowercase letters).
This will allow Spring Boot to use the same logic as it does when relaxed binding For example, |
You can also use this technique to create “short” variants of existing Spring Boot properties. See the Use ‘Short’ Command Line Arguments how-to for details. |
Working With Multi-Document Files
Spring Boot allows you to split a single physical file into multiple logical documents which are each added independently. Documents are processed in order, from top to bottom. Later documents can override the properties defined in earlier ones.
For application.yaml
files, the standard YAML multi-document syntax is used.
Three consecutive hyphens represent the end of one document, and the start of the next.
For example, the following file has two logical documents:
spring:
application:
name: "MyApp"
---
spring:
application:
name: "MyCloudApp"
config:
activate:
on-cloud-platform: "kubernetes"
For application.properties
files a special #---
or !---
comment is used to mark the document splits:
spring.application.name=MyApp
#---
spring.application.name=MyCloudApp
spring.config.activate.on-cloud-platform=kubernetes
Property file separators must not have any leading whitespace and must have exactly three hyphen characters. The lines immediately before and after the separator must not be same comment prefix. |
Multi-document property files are often used in conjunction with activation properties such as spring.config.activate.on-profile .
See the next section for details.
|
Multi-document property files cannot be loaded by using the @PropertySource or @TestPropertySource annotations.
|
Activation Properties
It is sometimes useful to only activate a given set of properties when certain conditions are met. For example, you might have properties that are only relevant when a specific profile is active.
You can conditionally activate a properties document using spring.config.activate.*
.
The following activation properties are available:
Property | Note |
---|---|
|
A profile expression that must match for the document to be active. |
|
The |
For example, the following specifies that the second document is only active when running on Kubernetes, and only when either the “prod” or “staging” profiles are active:
myprop=always-set
#---
spring.config.activate.on-cloud-platform=kubernetes
spring.config.activate.on-profile=prod | staging
myotherprop=sometimes-set
myprop:
"always-set"
---
spring:
config:
activate:
on-cloud-platform: "kubernetes"
on-profile: "prod | staging"
myotherprop: "sometimes-set"
7.2.4. Encrypting Properties
Spring Boot does not provide any built-in support for encrypting property values, however, it does provide the hook points necessary to modify values contained in the Spring Environment
.
The EnvironmentPostProcessor
interface allows you to manipulate the Environment
before the application starts.
See Customize the Environment or ApplicationContext Before It Starts for details.
If you need a secure way to store credentials and passwords, the Spring Cloud Vault project provides support for storing externalized configuration in HashiCorp Vault.
7.2.5. Working With YAML
YAML is a superset of JSON and, as such, is a convenient format for specifying hierarchical configuration data.
The SpringApplication
class automatically supports YAML as an alternative to properties whenever you have the SnakeYAML library on your classpath.
If you use “Starters”, SnakeYAML is automatically provided by spring-boot-starter .
|
Mapping YAML to Properties
YAML documents need to be converted from their hierarchical format to a flat structure that can be used with the Spring Environment
.
For example, consider the following YAML document:
environments:
dev:
url: "https://dev.example.com"
name: "Developer Setup"
prod:
url: "https://another.example.com"
name: "My Cool App"
In order to access these properties from the Environment
, they would be flattened as follows:
environments.dev.url=https://dev.example.com
environments.dev.name=Developer Setup
environments.prod.url=https://another.example.com
environments.prod.name=My Cool App
Likewise, YAML lists also need to be flattened.
They are represented as property keys with [index]
dereferencers.
For example, consider the following YAML:
my:
servers:
- "dev.example.com"
- "another.example.com"
The preceding example would be transformed into these properties:
my.servers[0]=dev.example.com
my.servers[1]=another.example.com
Properties that use the [index] notation can be bound to Java List or Set objects using Spring Boot’s Binder class.
For more details see the “Type-safe Configuration Properties” section below.
|
YAML files cannot be loaded by using the @PropertySource or @TestPropertySource annotations.
So, in the case that you need to load values that way, you need to use a properties file.
|
Directly Loading YAML
Spring Framework provides two convenient classes that can be used to load YAML documents.
The YamlPropertiesFactoryBean
loads YAML as Properties
and the YamlMapFactoryBean
loads YAML as a Map
.
You can also use the YamlPropertySourceLoader
class if you want to load YAML as a Spring PropertySource
.
7.2.6. Configuring Random Values
The RandomValuePropertySource
is useful for injecting random values (for example, into secrets or test cases).
It can produce integers, longs, uuids, or strings, as shown in the following example:
my.secret=${random.value}
my.number=${random.int}
my.bignumber=${random.long}
my.uuid=${random.uuid}
my.number-less-than-ten=${random.int(10)}
my.number-in-range=${random.int[1024,65536]}
my:
secret: "${random.value}"
number: "${random.int}"
bignumber: "${random.long}"
uuid: "${random.uuid}"
number-less-than-ten: "${random.int(10)}"
number-in-range: "${random.int[1024,65536]}"
The random.int*
syntax is OPEN value (,max) CLOSE
where the OPEN,CLOSE
are any character and value,max
are integers.
If max
is provided, then value
is the minimum value and max
is the maximum value (exclusive).
7.2.7. Configuring System Environment Properties
Spring Boot supports setting a prefix for environment properties.
This is useful if the system environment is shared by multiple Spring Boot applications with different configuration requirements.
The prefix for system environment properties can be set directly on SpringApplication
.
For example, if you set the prefix to input
, a property such as remote.timeout
will also be resolved as input.remote.timeout
in the system environment.
7.2.8. Type-safe Configuration Properties
Using the @Value("${property}")
annotation to inject configuration properties can sometimes be cumbersome, especially if you are working with multiple properties or your data is hierarchical in nature.
Spring Boot provides an alternative method of working with properties that lets strongly typed beans govern and validate the configuration of your application.
JavaBean Properties Binding
It is possible to bind a bean declaring standard JavaBean properties as shown in the following example:
@ConfigurationProperties("my.service")
public class MyProperties {
private boolean enabled;
private InetAddress remoteAddress;
private final Security security = new Security();
public static class Security {
private String username;
private String password;
private List<String> roles = new ArrayList<>(Collections.singleton("USER"));
}
}
@ConfigurationProperties("my.service")
class MyProperties {
var isEnabled = false
var remoteAddress: InetAddress? = null
val security = Security()
class Security {
var username: String? = null
var password: String? = null
var roles: List<String> = ArrayList(setOf("USER"))
}
}
The preceding POJO defines the following properties:
-
my.service.enabled
, with a value offalse
by default. -
my.service.remote-address
, with a type that can be coerced fromString
. -
my.service.security.username
, with a nested "security" object whose name is determined by the name of the property. In particular, the type is not used at all there and could have beenSecurityProperties
. -
my.service.security.password
. -
my.service.security.roles
, with a collection ofString
that defaults toUSER
.
The properties that map to @ConfigurationProperties classes available in Spring Boot, which are configured through properties files, YAML files, environment variables, and other mechanisms, are public API but the accessors (getters/setters) of the class itself are not meant to be used directly.
|
Such arrangement relies on a default empty constructor and getters and setters are usually mandatory, since binding is through standard Java Beans property descriptors, just like in Spring MVC. A setter may be omitted in the following cases:
Some people use Project Lombok to add getters and setters automatically. Make sure that Lombok does not generate any particular constructor for such a type, as it is used automatically by the container to instantiate the object. Finally, only standard Java Bean properties are considered and binding on static properties is not supported. |
Constructor Binding
The example in the previous section can be rewritten in an immutable fashion as shown in the following example:
@ConfigurationProperties("my.service")
public class MyProperties {
public MyProperties(boolean enabled, InetAddress remoteAddress, Security security) {
this.enabled = enabled;
this.remoteAddress = remoteAddress;
this.security = security;
}
public static class Security {
public Security(String username, String password, @DefaultValue("USER") List<String> roles) {
this.username = username;
this.password = password;
this.roles = roles;
}
}
}
@ConfigurationProperties("my.service")
class MyProperties(val enabled: Boolean, val remoteAddress: InetAddress,
val security: Security) {
class Security(val username: String, val password: String,
@param:DefaultValue("USER") val roles: List<String>)
}
In this setup, the presence of a single parameterized constructor implies that constructor binding should be used.
This means that the binder will find a constructor with the parameters that you wish to have bound.
If your class has multiple constructors, the @ConstructorBinding
annotation can be used to specify which constructor to use for constructor binding.
To opt out of constructor binding for a class with a single parameterized constructor, the constructor must be annotated with @Autowired
.
Constructor binding can be used with records.
Unless your record has multiple constructors, there is no need to use @ConstructorBinding
.
Nested members of a constructor bound class (such as Security
in the example above) will also be bound through their constructor.
Default values can be specified using @DefaultValue
on constructor parameters and record components.
The conversion service will be applied to coerce the annotation’s String
value to the target type of a missing property.
Referring to the previous example, if no properties are bound to Security
, the MyProperties
instance will contain a null
value for security
.
To make it contain a non-null instance of Security
even when no properties are bound to it (when using Kotlin, this will require the username
and password
parameters of Security
to be declared as nullable as they do not have default values), use an empty @DefaultValue
annotation:
public MyProperties(boolean enabled, InetAddress remoteAddress, @DefaultValue Security security) {
this.enabled = enabled;
this.remoteAddress = remoteAddress;
this.security = security;
}
class MyProperties(val enabled: Boolean, val remoteAddress: InetAddress,
@DefaultValue val security: Security) {
class Security(val username: String?, val password: String?,
@param:DefaultValue("USER") val roles: List<String>)
}
To use constructor binding the class must be enabled using @EnableConfigurationProperties or configuration property scanning.
You cannot use constructor binding with beans that are created by the regular Spring mechanisms (for example @Component beans, beans created by using @Bean methods or beans loaded by using @Import )
|
To use constructor binding in a native image the class must be compiled with -parameters .
This will happen automatically if you use Spring Boot’s Gradle plugin or if you use Maven and spring-boot-starter-parent .
|
The use of java.util.Optional with @ConfigurationProperties is not recommended as it is primarily intended for use as a return type.
As such, it is not well-suited to configuration property injection.
For consistency with properties of other types, if you do declare an Optional property and it has no value, null rather than an empty Optional will be bound.
|
Enabling @ConfigurationProperties-annotated Types
Spring Boot provides infrastructure to bind @ConfigurationProperties
types and register them as beans.
You can either enable configuration properties on a class-by-class basis or enable configuration property scanning that works in a similar manner to component scanning.
Sometimes, classes annotated with @ConfigurationProperties
might not be suitable for scanning, for example, if you’re developing your own auto-configuration or you want to enable them conditionally.
In these cases, specify the list of types to process using the @EnableConfigurationProperties
annotation.
This can be done on any @Configuration
class, as shown in the following example:
@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties(SomeProperties.class)
public class MyConfiguration {
}
@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties(SomeProperties::class)
class MyConfiguration
@ConfigurationProperties("some.properties")
public class SomeProperties {
}
@ConfigurationProperties("some.properties")
class SomeProperties
To use configuration property scanning, add the @ConfigurationPropertiesScan
annotation to your application.
Typically, it is added to the main application class that is annotated with @SpringBootApplication
but it can be added to any @Configuration
class.
By default, scanning will occur from the package of the class that declares the annotation.
If you want to define specific packages to scan, you can do so as shown in the following example:
@SpringBootApplication
@ConfigurationPropertiesScan({ "com.example.app", "com.example.another" })
public class MyApplication {
}
@SpringBootApplication
@ConfigurationPropertiesScan("com.example.app", "com.example.another")
class MyApplication
When the Assuming that it is in the |
We recommend that @ConfigurationProperties
only deal with the environment and, in particular, does not inject other beans from the context.
For corner cases, setter injection can be used or any of the *Aware
interfaces provided by the framework (such as EnvironmentAware
if you need access to the Environment
).
If you still want to inject other beans using the constructor, the configuration properties bean must be annotated with @Component
and use JavaBean-based property binding.
Using @ConfigurationProperties-annotated Types
This style of configuration works particularly well with the SpringApplication
external YAML configuration, as shown in the following example:
my:
service:
remote-address: 192.168.1.1
security:
username: "admin"
roles:
- "USER"
- "ADMIN"
To work with @ConfigurationProperties
beans, you can inject them in the same way as any other bean, as shown in the following example:
@Service
public class MyService {
private final MyProperties properties;
public MyService(MyProperties properties) {
this.properties = properties;
}
public void openConnection() {
Server server = new Server(this.properties.getRemoteAddress());
server.start();
// ...
}
// ...
}
@Service
class MyService(val properties: MyProperties) {
fun openConnection() {
val server = Server(properties.remoteAddress)
server.start()
// ...
}
// ...
}
Using @ConfigurationProperties also lets you generate metadata files that can be used by IDEs to offer auto-completion for your own keys.
See the appendix for details.
|
Third-party Configuration
As well as using @ConfigurationProperties
to annotate a class, you can also use it on public @Bean
methods.
Doing so can be particularly useful when you want to bind properties to third-party components that are outside of your control.
To configure a bean from the Environment
properties, add @ConfigurationProperties
to its bean registration, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class ThirdPartyConfiguration {
@Bean
@ConfigurationProperties(prefix = "another")
public AnotherComponent anotherComponent() {
return new AnotherComponent();
}
}
@Configuration(proxyBeanMethods = false)
class ThirdPartyConfiguration {
@Bean
@ConfigurationProperties(prefix = "another")
fun anotherComponent(): AnotherComponent = AnotherComponent()
}
Any JavaBean property defined with the another
prefix is mapped onto that AnotherComponent
bean in manner similar to the preceding SomeProperties
example.
Relaxed Binding
Spring Boot uses some relaxed rules for binding Environment
properties to @ConfigurationProperties
beans, so there does not need to be an exact match between the Environment
property name and the bean property name.
Common examples where this is useful include dash-separated environment properties (for example, context-path
binds to contextPath
), and capitalized environment properties (for example, PORT
binds to port
).
As an example, consider the following @ConfigurationProperties
class:
@ConfigurationProperties(prefix = "my.main-project.person")
public class MyPersonProperties {
private String firstName;
public String getFirstName() {
return this.firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
}
@ConfigurationProperties(prefix = "my.main-project.person")
class MyPersonProperties {
var firstName: String? = null
}
With the preceding code, the following properties names can all be used:
Property | Note |
---|---|
|
Kebab case, which is recommended for use in |
|
Standard camel case syntax. |
|
Underscore notation, which is an alternative format for use in |
|
Upper case format, which is recommended when using system environment variables. |
The prefix value for the annotation must be in kebab case (lowercase and separated by - , such as my.main-project.person ).
|
Property Source | Simple | List |
---|---|---|
Properties Files |
Camel case, kebab case, or underscore notation |
Standard list syntax using |
YAML Files |
Camel case, kebab case, or underscore notation |
Standard YAML list syntax or comma-separated values |
Environment Variables |
Upper case format with underscore as the delimiter (see Binding From Environment Variables). |
Numeric values surrounded by underscores (see Binding From Environment Variables) |
System properties |
Camel case, kebab case, or underscore notation |
Standard list syntax using |
We recommend that, when possible, properties are stored in lower-case kebab format, such as my.person.first-name=Rod .
|
Binding Maps
When binding to Map
properties you may need to use a special bracket notation so that the original key
value is preserved.
If the key is not surrounded by []
, any characters that are not alpha-numeric, -
or .
are removed.
For example, consider binding the following properties to a Map<String,String>
:
my.map.[/key1]=value1
my.map.[/key2]=value2
my.map./key3=value3
my:
map:
"[/key1]": "value1"
"[/key2]": "value2"
"/key3": "value3"
For YAML files, the brackets need to be surrounded by quotes for the keys to be parsed properly. |
The properties above will bind to a Map
with /key1
, /key2
and key3
as the keys in the map.
The slash has been removed from key3
because it was not surrounded by square brackets.
When binding to scalar values, keys with .
in them do not need to be surrounded by []
.
Scalar values include enums and all types in the java.lang
package except for Object
.
Binding a.b=c
to Map<String, String>
will preserve the .
in the key and return a Map with the entry {"a.b"="c"}
.
For any other types you need to use the bracket notation if your key
contains a .
.
For example, binding a.b=c
to Map<String, Object>
will return a Map with the entry {"a"={"b"="c"}}
whereas [a.b]=c
will return a Map with the entry {"a.b"="c"}
.
Binding From Environment Variables
Most operating systems impose strict rules around the names that can be used for environment variables.
For example, Linux shell variables can contain only letters (a
to z
or A
to Z
), numbers (0
to 9
) or the underscore character (_
).
By convention, Unix shell variables will also have their names in UPPERCASE.
Spring Boot’s relaxed binding rules are, as much as possible, designed to be compatible with these naming restrictions.
To convert a property name in the canonical-form to an environment variable name you can follow these rules:
-
Replace dots (
.
) with underscores (_
). -
Remove any dashes (
-
). -
Convert to uppercase.
For example, the configuration property spring.main.log-startup-info
would be an environment variable named SPRING_MAIN_LOGSTARTUPINFO
.
Environment variables can also be used when binding to object lists.
To bind to a List
, the element number should be surrounded with underscores in the variable name.
For example, the configuration property my.service[0].other
would use an environment variable named MY_SERVICE_0_OTHER
.
Merging Complex Types
When lists are configured in more than one place, overriding works by replacing the entire list.
For example, assume a MyPojo
object with name
and description
attributes that are null
by default.
The following example exposes a list of MyPojo
objects from MyProperties
:
@ConfigurationProperties("my")
public class MyProperties {
private final List<MyPojo> list = new ArrayList<>();
public List<MyPojo> getList() {
return this.list;
}
}
@ConfigurationProperties("my")
class MyProperties {
val list: List<MyPojo> = ArrayList()
}
Consider the following configuration:
my.list[0].name=my name
my.list[0].description=my description
#---
spring.config.activate.on-profile=dev
my.list[0].name=my another name
my:
list:
- name: "my name"
description: "my description"
---
spring:
config:
activate:
on-profile: "dev"
my:
list:
- name: "my another name"
If the dev
profile is not active, MyProperties.list
contains one MyPojo
entry, as previously defined.
If the dev
profile is enabled, however, the list
still contains only one entry (with a name of my another name
and a description of null
).
This configuration does not add a second MyPojo
instance to the list, and it does not merge the items.
When a List
is specified in multiple profiles, the one with the highest priority (and only that one) is used.
Consider the following example:
my.list[0].name=my name
my.list[0].description=my description
my.list[1].name=another name
my.list[1].description=another description
#---
spring.config.activate.on-profile=dev
my.list[0].name=my another name
my:
list:
- name: "my name"
description: "my description"
- name: "another name"
description: "another description"
---
spring:
config:
activate:
on-profile: "dev"
my:
list:
- name: "my another name"
In the preceding example, if the dev
profile is active, MyProperties.list
contains one MyPojo
entry (with a name of my another name
and a description of null
).
For YAML, both comma-separated lists and YAML lists can be used for completely overriding the contents of the list.
For Map
properties, you can bind with property values drawn from multiple sources.
However, for the same property in multiple sources, the one with the highest priority is used.
The following example exposes a Map<String, MyPojo>
from MyProperties
:
@ConfigurationProperties("my")
public class MyProperties {
private final Map<String, MyPojo> map = new LinkedHashMap<>();
public Map<String, MyPojo> getMap() {
return this.map;
}
}
@ConfigurationProperties("my")
class MyProperties {
val map: Map<String, MyPojo> = LinkedHashMap()
}
Consider the following configuration:
my.map.key1.name=my name 1
my.map.key1.description=my description 1
#---
spring.config.activate.on-profile=dev
my.map.key1.name=dev name 1
my.map.key2.name=dev name 2
my.map.key2.description=dev description 2
my:
map:
key1:
name: "my name 1"
description: "my description 1"
---
spring:
config:
activate:
on-profile: "dev"
my:
map:
key1:
name: "dev name 1"
key2:
name: "dev name 2"
description: "dev description 2"
If the dev
profile is not active, MyProperties.map
contains one entry with key key1
(with a name of my name 1
and a description of my description 1
).
If the dev
profile is enabled, however, map
contains two entries with keys key1
(with a name of dev name 1
and a description of my description 1
) and key2
(with a name of dev name 2
and a description of dev description 2
).
The preceding merging rules apply to properties from all property sources, and not just files. |
Properties Conversion
Spring Boot attempts to coerce the external application properties to the right type when it binds to the @ConfigurationProperties
beans.
If you need custom type conversion, you can provide a ConversionService
bean (with a bean named conversionService
) or custom property editors (through a CustomEditorConfigurer
bean) or custom Converters
(with bean definitions annotated as @ConfigurationPropertiesBinding
).
As this bean is requested very early during the application lifecycle, make sure to limit the dependencies that your ConversionService is using.
Typically, any dependency that you require may not be fully initialized at creation time.
You may want to rename your custom ConversionService if it is not required for configuration keys coercion and only rely on custom converters qualified with @ConfigurationPropertiesBinding .
|
Converting Durations
Spring Boot has dedicated support for expressing durations.
If you expose a java.time.Duration
property, the following formats in application properties are available:
-
A regular
long
representation (using milliseconds as the default unit unless a@DurationUnit
has been specified) -
The standard ISO-8601 format used by
java.time.Duration
-
A more readable format where the value and the unit are coupled (
10s
means 10 seconds)
Consider the following example:
@ConfigurationProperties("my")
public class MyProperties {
@DurationUnit(ChronoUnit.SECONDS)
private Duration sessionTimeout = Duration.ofSeconds(30);
private Duration readTimeout = Duration.ofMillis(1000);
}
@ConfigurationProperties("my")
class MyProperties {
@DurationUnit(ChronoUnit.SECONDS)
var sessionTimeout = Duration.ofSeconds(30)
var readTimeout = Duration.ofMillis(1000)
}
To specify a session timeout of 30 seconds, 30
, PT30S
and 30s
are all equivalent.
A read timeout of 500ms can be specified in any of the following form: 500
, PT0.5S
and 500ms
.
You can also use any of the supported units. These are:
-
ns
for nanoseconds -
us
for microseconds -
ms
for milliseconds -
s
for seconds -
m
for minutes -
h
for hours -
d
for days
The default unit is milliseconds and can be overridden using @DurationUnit
as illustrated in the sample above.
If you prefer to use constructor binding, the same properties can be exposed, as shown in the following example:
@ConfigurationProperties("my")
public class MyProperties {
public MyProperties(@DurationUnit(ChronoUnit.SECONDS) @DefaultValue("30s") Duration sessionTimeout,
@DefaultValue("1000ms") Duration readTimeout) {
this.sessionTimeout = sessionTimeout;
this.readTimeout = readTimeout;
}
}
@ConfigurationProperties("my")
class MyProperties(@param:DurationUnit(ChronoUnit.SECONDS) @param:DefaultValue("30s") val sessionTimeout: Duration,
@param:DefaultValue("1000ms") val readTimeout: Duration)
If you are upgrading a Long property, make sure to define the unit (using @DurationUnit ) if it is not milliseconds.
Doing so gives a transparent upgrade path while supporting a much richer format.
|
Converting Periods
In addition to durations, Spring Boot can also work with java.time.Period
type.
The following formats can be used in application properties:
-
An regular
int
representation (using days as the default unit unless a@PeriodUnit
has been specified) -
The standard ISO-8601 format used by
java.time.Period
-
A simpler format where the value and the unit pairs are coupled (
1y3d
means 1 year and 3 days)
The following units are supported with the simple format:
-
y
for years -
m
for months -
w
for weeks -
d
for days
The java.time.Period type never actually stores the number of weeks, it is a shortcut that means “7 days”.
|
Converting Data Sizes
Spring Framework has a DataSize
value type that expresses a size in bytes.
If you expose a DataSize
property, the following formats in application properties are available:
-
A regular
long
representation (using bytes as the default unit unless a@DataSizeUnit
has been specified) -
A more readable format where the value and the unit are coupled (
10MB
means 10 megabytes)
Consider the following example:
@ConfigurationProperties("my")
public class MyProperties {
@DataSizeUnit(DataUnit.MEGABYTES)
private DataSize bufferSize = DataSize.ofMegabytes(2);
private DataSize sizeThreshold = DataSize.ofBytes(512);
}
@ConfigurationProperties("my")
class MyProperties {
@DataSizeUnit(DataUnit.MEGABYTES)
var bufferSize = DataSize.ofMegabytes(2)
var sizeThreshold = DataSize.ofBytes(512)
}
To specify a buffer size of 10 megabytes, 10
and 10MB
are equivalent.
A size threshold of 256 bytes can be specified as 256
or 256B
.
You can also use any of the supported units. These are:
-
B
for bytes -
KB
for kilobytes -
MB
for megabytes -
GB
for gigabytes -
TB
for terabytes
The default unit is bytes and can be overridden using @DataSizeUnit
as illustrated in the sample above.
If you prefer to use constructor binding, the same properties can be exposed, as shown in the following example:
@ConfigurationProperties("my")
public class MyProperties {
public MyProperties(@DataSizeUnit(DataUnit.MEGABYTES) @DefaultValue("2MB") DataSize bufferSize,
@DefaultValue("512B") DataSize sizeThreshold) {
this.bufferSize = bufferSize;
this.sizeThreshold = sizeThreshold;
}
}
@ConfigurationProperties("my")
class MyProperties(@param:DataSizeUnit(DataUnit.MEGABYTES) @param:DefaultValue("2MB") val bufferSize: DataSize,
@param:DefaultValue("512B") val sizeThreshold: DataSize)
If you are upgrading a Long property, make sure to define the unit (using @DataSizeUnit ) if it is not bytes.
Doing so gives a transparent upgrade path while supporting a much richer format.
|
@ConfigurationProperties Validation
Spring Boot attempts to validate @ConfigurationProperties
classes whenever they are annotated with Spring’s @Validated
annotation.
You can use JSR-303 jakarta.validation
constraint annotations directly on your configuration class.
To do so, ensure that a compliant JSR-303 implementation is on your classpath and then add constraint annotations to your fields, as shown in the following example:
@ConfigurationProperties("my.service")
@Validated
public class MyProperties {
@NotNull
private InetAddress remoteAddress;
}
@ConfigurationProperties("my.service")
@Validated
class MyProperties {
var remoteAddress: @NotNull InetAddress? = null
}
You can also trigger validation by annotating the @Bean method that creates the configuration properties with @Validated .
|
To ensure that validation is always triggered for nested properties, even when no properties are found, the associated field must be annotated with @Valid
.
The following example builds on the preceding MyProperties
example:
@ConfigurationProperties("my.service")
@Validated
public class MyProperties {
@NotNull
private InetAddress remoteAddress;
@Valid
private final Security security = new Security();
public static class Security {
@NotEmpty
private String username;
}
}
@ConfigurationProperties("my.service")
@Validated
class MyProperties {
var remoteAddress: @NotNull InetAddress? = null
@Valid
val security = Security()
class Security {
@NotEmpty
var username: String? = null
}
}
You can also add a custom Spring Validator
by creating a bean definition called configurationPropertiesValidator
.
The @Bean
method should be declared static
.
The configuration properties validator is created very early in the application’s lifecycle, and declaring the @Bean
method as static lets the bean be created without having to instantiate the @Configuration
class.
Doing so avoids any problems that may be caused by early instantiation.
The spring-boot-actuator module includes an endpoint that exposes all @ConfigurationProperties beans.
Point your web browser to /actuator/configprops or use the equivalent JMX endpoint.
See the "Production ready features" section for details.
|
@ConfigurationProperties vs. @Value
The @Value
annotation is a core container feature, and it does not provide the same features as type-safe configuration properties.
The following table summarizes the features that are supported by @ConfigurationProperties
and @Value
:
Feature | @ConfigurationProperties |
@Value |
---|---|---|
Yes |
Limited (see note below) |
|
Yes |
No |
|
|
No |
Yes |
If you do want to use For example, |
If you define a set of configuration keys for your own components, we recommend you group them in a POJO annotated with @ConfigurationProperties
.
Doing so will provide you with structured, type-safe object that you can inject into your own beans.
SpEL
expressions from application property files are not processed at time of parsing these files and populating the environment.
However, it is possible to write a SpEL
expression in @Value
.
If the value of a property from an application property file is a SpEL
expression, it will be evaluated when consumed through @Value
.
7.3. Profiles
Spring Profiles provide a way to segregate parts of your application configuration and make it be available only in certain environments.
Any @Component
, @Configuration
or @ConfigurationProperties
can be marked with @Profile
to limit when it is loaded, as shown in the following example:
@Configuration(proxyBeanMethods = false)
@Profile("production")
public class ProductionConfiguration {
// ...
}
@Configuration(proxyBeanMethods = false)
@Profile("production")
class ProductionConfiguration {
// ...
}
If @ConfigurationProperties beans are registered through @EnableConfigurationProperties instead of automatic scanning, the @Profile annotation needs to be specified on the @Configuration class that has the @EnableConfigurationProperties annotation.
In the case where @ConfigurationProperties are scanned, @Profile can be specified on the @ConfigurationProperties class itself.
|
You can use a spring.profiles.active
Environment
property to specify which profiles are active.
You can specify the property in any of the ways described earlier in this chapter.
For example, you could include it in your application.properties
, as shown in the following example:
spring.profiles.active=dev,hsqldb
spring:
profiles:
active: "dev,hsqldb"
You could also specify it on the command line by using the following switch: --spring.profiles.active=dev,hsqldb
.
If no profile is active, a default profile is enabled.
The name of the default profile is default
and it can be tuned using the spring.profiles.default
Environment
property, as shown in the following example:
spring.profiles.default=none
spring:
profiles:
default: "none"
spring.profiles.active
and spring.profiles.default
can only be used in non-profile specific documents.
This means they cannot be included in profile specific files or documents activated by spring.config.activate.on-profile
.
For example, the second document configuration is invalid:
# this document is valid
spring.profiles.active=prod
#---
# this document is invalid
spring.config.activate.on-profile=prod
spring.profiles.active=metrics
# this document is valid
spring:
profiles:
active: "prod"
---
# this document is invalid
spring:
config:
activate:
on-profile: "prod"
profiles:
active: "metrics"
7.3.1. Adding Active Profiles
The spring.profiles.active
property follows the same ordering rules as other properties: The highest PropertySource
wins.
This means that you can specify active profiles in application.properties
and then replace them by using the command line switch.
Sometimes, it is useful to have properties that add to the active profiles rather than replace them.
The spring.profiles.include
property can be used to add active profiles on top of those activated by the spring.profiles.active
property.
The SpringApplication
entry point also has a Java API for setting additional profiles.
See the setAdditionalProfiles()
method in SpringApplication.
For example, when an application with the following properties is run, the common and local profiles will be activated even when it runs using the --spring.profiles.active
switch:
spring.profiles.include[0]=common
spring.profiles.include[1]=local
spring:
profiles:
include:
- "common"
- "local"
Similar to spring.profiles.active , spring.profiles.include can only be used in non-profile specific documents.
This means it cannot be included in profile specific files or documents activated by spring.config.activate.on-profile .
|
Profile groups, which are described in the next section can also be used to add active profiles if a given profile is active.
7.3.2. Profile Groups
Occasionally the profiles that you define and use in your application are too fine-grained and become cumbersome to use.
For example, you might have proddb
and prodmq
profiles that you use to enable database and messaging features independently.
To help with this, Spring Boot lets you define profile groups. A profile group allows you to define a logical name for a related group of profiles.
For example, we can create a production
group that consists of our proddb
and prodmq
profiles.
spring.profiles.group.production[0]=proddb
spring.profiles.group.production[1]=prodmq
spring:
profiles:
group:
production:
- "proddb"
- "prodmq"
Our application can now be started using --spring.profiles.active=production
to activate the production
, proddb
and prodmq
profiles in one hit.
7.3.3. Programmatically Setting Profiles
You can programmatically set active profiles by calling SpringApplication.setAdditionalProfiles(…)
before your application runs.
It is also possible to activate profiles by using Spring’s ConfigurableEnvironment
interface.
7.3.4. Profile-specific Configuration Files
Profile-specific variants of both application.properties
(or application.yaml
) and files referenced through @ConfigurationProperties
are considered as files and loaded.
See "Profile Specific Files" for details.
7.4. Logging
Spring Boot uses Commons Logging for all internal logging but leaves the underlying log implementation open. Default configurations are provided for Java Util Logging, Log4j2, and Logback. In each case, loggers are pre-configured to use console output with optional file output also available.
By default, if you use the “Starters”, Logback is used for logging. Appropriate Logback routing is also included to ensure that dependent libraries that use Java Util Logging, Commons Logging, Log4J, or SLF4J all work correctly.
There are a lot of logging frameworks available for Java. Do not worry if the above list seems confusing. Generally, you do not need to change your logging dependencies and the Spring Boot defaults work just fine. |
When you deploy your application to a servlet container or application server, logging performed with the Java Util Logging API is not routed into your application’s logs. This prevents logging performed by the container or other applications that have been deployed to it from appearing in your application’s logs. |
7.4.1. Log Format
The default log output from Spring Boot resembles the following example:
2023-11-23T12:27:30.527Z INFO 36833 --- [myapp] [ main] o.s.b.d.f.logexample.MyApplication : Starting MyApplication using Java 17.0.9 with PID 36833 (/opt/apps/myapp.jar started by myuser in /opt/apps/) 2023-11-23T12:27:30.534Z INFO 36833 --- [myapp] [ main] o.s.b.d.f.logexample.MyApplication : No active profile set, falling back to 1 default profile: "default" 2023-11-23T12:27:32.960Z INFO 36833 --- [myapp] [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port 8080 (http) 2023-11-23T12:27:33.005Z INFO 36833 --- [myapp] [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat] 2023-11-23T12:27:33.006Z INFO 36833 --- [myapp] [ main] o.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/10.1.16] 2023-11-23T12:27:33.151Z INFO 36833 --- [myapp] [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2023-11-23T12:27:33.165Z INFO 36833 --- [myapp] [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 2482 ms 2023-11-23T12:27:34.218Z INFO 36833 --- [myapp] [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port 8080 (http) with context path '' 2023-11-23T12:27:34.235Z INFO 36833 --- [myapp] [ main] o.s.b.d.f.logexample.MyApplication : Started MyApplication in 4.826 seconds (process running for 5.441)
The following items are output:
-
Date and Time: Millisecond precision and easily sortable.
-
Log Level:
ERROR
,WARN
,INFO
,DEBUG
, orTRACE
. -
Process ID.
-
A
---
separator to distinguish the start of actual log messages. -
Application name: Enclosed in square brackets (logged by default only if
spring.application.name
is set) -
Thread name: Enclosed in square brackets (may be truncated for console output).
-
Correlation ID: If tracing is enabled (not shown in the sample above)
-
Logger name: This is usually the source class name (often abbreviated).
-
The log message.
Logback does not have a FATAL level.
It is mapped to ERROR .
|
If you have a spring.application.name property but don’t want it logged you can set logging.include-application-name to false .
|
7.4.2. Console Output
The default log configuration echoes messages to the console as they are written.
By default, ERROR
-level, WARN
-level, and INFO
-level messages are logged.
You can also enable a “debug” mode by starting your application with a --debug
flag.
$ java -jar myapp.jar --debug
You can also specify debug=true in your application.properties .
|
When the debug mode is enabled, a selection of core loggers (embedded container, Hibernate, and Spring Boot) are configured to output more information.
Enabling the debug mode does not configure your application to log all messages with DEBUG
level.
Alternatively, you can enable a “trace” mode by starting your application with a --trace
flag (or trace=true
in your application.properties
).
Doing so enables trace logging for a selection of core loggers (embedded container, Hibernate schema generation, and the whole Spring portfolio).
Color-coded Output
If your terminal supports ANSI, color output is used to aid readability.
You can set spring.output.ansi.enabled
to a supported value to override the auto-detection.
Color coding is configured by using the %clr
conversion word.
In its simplest form, the converter colors the output according to the log level, as shown in the following example:
%clr(%5p)
The following table describes the mapping of log levels to colors:
Level | Color |
---|---|
|
Red |
|
Red |
|
Yellow |
|
Green |
|
Green |
|
Green |
Alternatively, you can specify the color or style that should be used by providing it as an option to the conversion. For example, to make the text yellow, use the following setting:
%clr(%d{yyyy-MM-dd'T'HH:mm:ss.SSSXXX}){yellow}
The following colors and styles are supported:
-
blue
-
cyan
-
faint
-
green
-
magenta
-
red
-
yellow
7.4.3. File Output
By default, Spring Boot logs only to the console and does not write log files.
If you want to write log files in addition to the console output, you need to set a logging.file.name
or logging.file.path
property (for example, in your application.properties
).
The following table shows how the logging.*
properties can be used together:
logging.file.name |
logging.file.path |
Example | Description |
---|---|---|---|
(none) |
(none) |
Console only logging. |
|
Specific file |
(none) |
|
Writes to the specified log file. Names can be an exact location or relative to the current directory. |
(none) |
Specific directory |
|
Writes |
Log files rotate when they reach 10 MB and, as with console output, ERROR
-level, WARN
-level, and INFO
-level messages are logged by default.
Logging properties are independent of the actual logging infrastructure.
As a result, specific configuration keys (such as logback.configurationFile for Logback) are not managed by spring Boot.
|
7.4.4. File Rotation
If you are using the Logback, it is possible to fine-tune log rotation settings using your application.properties
or application.yaml
file.
For all other logging system, you will need to configure rotation settings directly yourself (for example, if you use Log4j2 then you could add a log4j2.xml
or log4j2-spring.xml
file).
The following rotation policy properties are supported:
Name | Description |
---|---|
|
The filename pattern used to create log archives. |
|
If log archive cleanup should occur when the application starts. |
|
The maximum size of log file before it is archived. |
|
The maximum amount of size log archives can take before being deleted. |
|
The maximum number of archive log files to keep (defaults to 7). |
7.4.5. Log Levels
All the supported logging systems can have the logger levels set in the Spring Environment
(for example, in application.properties
) by using logging.level.<logger-name>=<level>
where level
is one of TRACE, DEBUG, INFO, WARN, ERROR, FATAL, or OFF.
The root
logger can be configured by using logging.level.root
.
The following example shows potential logging settings in application.properties
:
logging.level.root=warn
logging.level.org.springframework.web=debug
logging.level.org.hibernate=error
logging:
level:
root: "warn"
org.springframework.web: "debug"
org.hibernate: "error"
It is also possible to set logging levels using environment variables.
For example, LOGGING_LEVEL_ORG_SPRINGFRAMEWORK_WEB=DEBUG
will set org.springframework.web
to DEBUG
.
The above approach will only work for package level logging.
Since relaxed binding always converts environment variables to lowercase, it is not possible to configure logging for an individual class in this way.
If you need to configure logging for a class, you can use the SPRING_APPLICATION_JSON variable.
|
7.4.6. Log Groups
It is often useful to be able to group related loggers together so that they can all be configured at the same time. For example, you might commonly change the logging levels for all Tomcat related loggers, but you can not easily remember top level packages.
To help with this, Spring Boot allows you to define logging groups in your Spring Environment
.
For example, here is how you could define a “tomcat” group by adding it to your application.properties
:
logging.group.tomcat=org.apache.catalina,org.apache.coyote,org.apache.tomcat
logging:
group:
tomcat: "org.apache.catalina,org.apache.coyote,org.apache.tomcat"
Once defined, you can change the level for all the loggers in the group with a single line:
logging.level.tomcat=trace
logging:
level:
tomcat: "trace"
Spring Boot includes the following pre-defined logging groups that can be used out-of-the-box:
Name | Loggers |
---|---|
web |
|
sql |
|
7.4.7. Using a Log Shutdown Hook
In order to release logging resources when your application terminates, a shutdown hook that will trigger log system cleanup when the JVM exits is provided.
This shutdown hook is registered automatically unless your application is deployed as a war file.
If your application has complex context hierarchies the shutdown hook may not meet your needs.
If it does not, disable the shutdown hook and investigate the options provided directly by the underlying logging system.
For example, Logback offers context selectors which allow each Logger to be created in its own context.
You can use the logging.register-shutdown-hook
property to disable the shutdown hook.
Setting it to false
will disable the registration.
You can set the property in your application.properties
or application.yaml
file:
logging.register-shutdown-hook=false
logging:
register-shutdown-hook: false
7.4.8. Custom Log Configuration
The various logging systems can be activated by including the appropriate libraries on the classpath and can be further customized by providing a suitable configuration file in the root of the classpath or in a location specified by the following Spring Environment
property: logging.config
.
You can force Spring Boot to use a particular logging system by using the org.springframework.boot.logging.LoggingSystem
system property.
The value should be the fully qualified class name of a LoggingSystem
implementation.
You can also disable Spring Boot’s logging configuration entirely by using a value of none
.
Since logging is initialized before the ApplicationContext is created, it is not possible to control logging from @PropertySources in Spring @Configuration files.
The only way to change the logging system or disable it entirely is through System properties.
|
Depending on your logging system, the following files are loaded:
Logging System | Customization |
---|---|
Logback |
|
Log4j2 |
|
JDK (Java Util Logging) |
|
When possible, we recommend that you use the -spring variants for your logging configuration (for example, logback-spring.xml rather than logback.xml ).
If you use standard configuration locations, Spring cannot completely control log initialization.
|
There are known classloading issues with Java Util Logging that cause problems when running from an 'executable jar'. We recommend that you avoid it when running from an 'executable jar' if at all possible. |
To help with the customization, some other properties are transferred from the Spring Environment
to System properties.
This allows the properties to be consumed by logging system configuration. For example, setting logging.file.name
in application.properties
or LOGGING_FILE_NAME
as an environment variable will result in the LOG_FILE
System property being set.
The properties that are transferred are described in the following table:
Spring Environment | System Property | Comments |
---|---|---|
|
|
The conversion word used when logging exceptions. |
|
|
If defined, it is used in the default log configuration. |
|
|
If defined, it is used in the default log configuration. |
|
|
The log pattern to use on the console (stdout). |
|
|
Appender pattern for log date format. |
|
|
The charset to use for console logging. |
|
|
The log level threshold to use for console logging. |
|
|
The log pattern to use in a file (if |
|
|
The charset to use for file logging (if |
|
|
The log level threshold to use for file logging. |
|
|
The format to use when rendering the log level (default |
|
|
The current process ID (discovered if possible and when not already defined as an OS environment variable). |
If you use Logback, the following properties are also transferred:
Spring Environment | System Property | Comments |
---|---|---|
|
|
Pattern for rolled-over log file names (default |
|
|
Whether to clean the archive log files on startup. |
|
|
Maximum log file size. |
|
|
Total size of log backups to be kept. |
|
|
Maximum number of archive log files to keep. |
All the supported logging systems can consult System properties when parsing their configuration files.
See the default configurations in spring-boot.jar
for examples:
If you want to use a placeholder in a logging property, you should use Spring Boot’s syntax and not the syntax of the underlying framework.
Notably, if you use Logback, you should use |
You can add MDC and other ad-hoc content to log lines by overriding only the 2019-08-30 12:30:04.031 user:someone INFO 22174 --- [ nio-8080-exec-0] demo.Controller Handling authenticated request |
7.4.9. Logback Extensions
Spring Boot includes a number of extensions to Logback that can help with advanced configuration.
You can use these extensions in your logback-spring.xml
configuration file.
Because the standard logback.xml configuration file is loaded too early, you cannot use extensions in it.
You need to either use logback-spring.xml or define a logging.config property.
|
The extensions cannot be used with Logback’s configuration scanning. If you attempt to do so, making changes to the configuration file results in an error similar to one of the following being logged: |
ERROR in ch.qos.logback.core.joran.spi.Interpreter@4:71 - no applicable action for [springProperty], current ElementPath is [[configuration][springProperty]] ERROR in ch.qos.logback.core.joran.spi.Interpreter@4:71 - no applicable action for [springProfile], current ElementPath is [[configuration][springProfile]]
Profile-specific Configuration
The <springProfile>
tag lets you optionally include or exclude sections of configuration based on the active Spring profiles.
Profile sections are supported anywhere within the <configuration>
element.
Use the name
attribute to specify which profile accepts the configuration.
The <springProfile>
tag can contain a profile name (for example staging
) or a profile expression.
A profile expression allows for more complicated profile logic to be expressed, for example production & (eu-central | eu-west)
.
Check the Spring Framework reference guide for more details.
The following listing shows three sample profiles:
<springProfile name="staging">
<!-- configuration to be enabled when the "staging" profile is active -->
</springProfile>
<springProfile name="dev | staging">
<!-- configuration to be enabled when the "dev" or "staging" profiles are active -->
</springProfile>
<springProfile name="!production">
<!-- configuration to be enabled when the "production" profile is not active -->
</springProfile>
Environment Properties
The <springProperty>
tag lets you expose properties from the Spring Environment
for use within Logback.
Doing so can be useful if you want to access values from your application.properties
file in your Logback configuration.
The tag works in a similar way to Logback’s standard <property>
tag.
However, rather than specifying a direct value
, you specify the source
of the property (from the Environment
).
If you need to store the property somewhere other than in local
scope, you can use the scope
attribute.
If you need a fallback value (in case the property is not set in the Environment
), you can use the defaultValue
attribute.
The following example shows how to expose properties for use within Logback:
<springProperty scope="context" name="fluentHost" source="myapp.fluentd.host"
defaultValue="localhost"/>
<appender name="FLUENT" class="ch.qos.logback.more.appenders.DataFluentAppender">
<remoteHost>${fluentHost}</remoteHost>
...
</appender>
The source must be specified in kebab case (such as my.property-name ).
However, properties can be added to the Environment by using the relaxed rules.
|
7.4.10. Log4j2 Extensions
Spring Boot includes a number of extensions to Log4j2 that can help with advanced configuration.
You can use these extensions in any log4j2-spring.xml
configuration file.
Because the standard log4j2.xml configuration file is loaded too early, you cannot use extensions in it.
You need to either use log4j2-spring.xml or define a logging.config property.
|
The extensions supersede the Spring Boot support provided by Log4J.
You should make sure not to include the org.apache.logging.log4j:log4j-spring-boot module in your build.
|
Profile-specific Configuration
The <SpringProfile>
tag lets you optionally include or exclude sections of configuration based on the active Spring profiles.
Profile sections are supported anywhere within the <Configuration>
element.
Use the name
attribute to specify which profile accepts the configuration.
The <SpringProfile>
tag can contain a profile name (for example staging
) or a profile expression.
A profile expression allows for more complicated profile logic to be expressed, for example production & (eu-central | eu-west)
.
Check the Spring Framework reference guide for more details.
The following listing shows three sample profiles:
<SpringProfile name="staging">
<!-- configuration to be enabled when the "staging" profile is active -->
</SpringProfile>
<SpringProfile name="dev | staging">
<!-- configuration to be enabled when the "dev" or "staging" profiles are active -->
</SpringProfile>
<SpringProfile name="!production">
<!-- configuration to be enabled when the "production" profile is not active -->
</SpringProfile>
Environment Properties Lookup
If you want to refer to properties from your Spring Environment
within your Log4j2 configuration you can use spring:
prefixed lookups.
Doing so can be useful if you want to access values from your application.properties
file in your Log4j2 configuration.
The following example shows how to set a Log4j2 property named applicationName
that reads spring.application.name
from the Spring Environment
:
<Properties>
<Property name="applicationName">${spring:spring.application.name}</Property>
</Properties>
The lookup key should be specified in kebab case (such as my.property-name ).
|
Log4j2 System Properties
Log4j2 supports a number of System Properties that can be used to configure various items.
For example, the log4j2.skipJansi
system property can be used to configure if the ConsoleAppender
will try to use a Jansi output stream on Windows.
All system properties that are loaded after the Log4j2 initialization can be obtained from the Spring Environment
.
For example, you could add log4j2.skipJansi=false
to your application.properties
file to have the ConsoleAppender
use Jansi on Windows.
The Spring Environment is only considered when system properties and OS environment variables do not contain the value being loaded.
|
System properties that are loaded during early Log4j2 initialization cannot reference the Spring Environment .
For example, the property Log4j2 uses to allow the default Log4j2 implementation to be chosen is used before the Spring Environment is available.
|
7.5. Internationalization
Spring Boot supports localized messages so that your application can cater to users of different language preferences.
By default, Spring Boot looks for the presence of a messages
resource bundle at the root of the classpath.
The auto-configuration applies when the default properties file for the configured resource bundle is available (messages.properties by default).
If your resource bundle contains only language-specific properties files, you are required to add the default.
If no properties file is found that matches any of the configured base names, there will be no auto-configured MessageSource .
|
The basename of the resource bundle as well as several other attributes can be configured using the spring.messages
namespace, as shown in the following example:
spring.messages.basename=messages,config.i18n.messages
spring.messages.fallback-to-system-locale=false
spring:
messages:
basename: "messages,config.i18n.messages"
fallback-to-system-locale: false
spring.messages.basename supports comma-separated list of locations, either a package qualifier or a resource resolved from the classpath root.
|
See MessageSourceProperties
for more supported options.
7.6. Aspect-Oriented Programming
Spring Boot provides auto-configuration for aspect-oriented programming (AOP). You can learn more about AOP with Spring in the Spring Framework reference documentation.
By default, Spring Boot’s auto-configuration configures Spring AOP to use CGLib proxies.
To use JDK proxies instead, set configprop:spring.aop.proxy-target-class
to false
.
If AspectJ is on the classpath, Spring Boot’s auto-configuration will automatically enable AspectJ auto proxy such that @EnableAspectJAutoProxy
is not required.
7.7. JSON
Spring Boot provides integration with three JSON mapping libraries:
-
Gson
-
Jackson
-
JSON-B
Jackson is the preferred and default library.
7.7.1. Jackson
Auto-configuration for Jackson is provided and Jackson is part of spring-boot-starter-json
.
When Jackson is on the classpath an ObjectMapper
bean is automatically configured.
Several configuration properties are provided for customizing the configuration of the ObjectMapper
.
Custom Serializers and Deserializers
If you use Jackson to serialize and deserialize JSON data, you might want to write your own JsonSerializer
and JsonDeserializer
classes.
Custom serializers are usually registered with Jackson through a module, but Spring Boot provides an alternative @JsonComponent
annotation that makes it easier to directly register Spring Beans.
You can use the @JsonComponent
annotation directly on JsonSerializer
, JsonDeserializer
or KeyDeserializer
implementations.
You can also use it on classes that contain serializers/deserializers as inner classes, as shown in the following example:
@JsonComponent
public class MyJsonComponent {
public static class Serializer extends JsonSerializer<MyObject> {
@Override
public void serialize(MyObject value, JsonGenerator jgen, SerializerProvider serializers) throws IOException {
jgen.writeStartObject();
jgen.writeStringField("name", value.getName());
jgen.writeNumberField("age", value.getAge());
jgen.writeEndObject();
}
}
public static class Deserializer extends JsonDeserializer<MyObject> {
@Override
public MyObject deserialize(JsonParser jsonParser, DeserializationContext ctxt) throws IOException {
ObjectCodec codec = jsonParser.getCodec();
JsonNode tree = codec.readTree(jsonParser);
String name = tree.get("name").textValue();
int age = tree.get("age").intValue();
return new MyObject(name, age);
}
}
}
@JsonComponent
class MyJsonComponent {
class Serializer : JsonSerializer<MyObject>() {
@Throws(IOException::class)
override fun serialize(value: MyObject, jgen: JsonGenerator, serializers: SerializerProvider) {
jgen.writeStartObject()
jgen.writeStringField("name", value.name)
jgen.writeNumberField("age", value.age)
jgen.writeEndObject()
}
}
class Deserializer : JsonDeserializer<MyObject>() {
@Throws(IOException::class, JsonProcessingException::class)
override fun deserialize(jsonParser: JsonParser, ctxt: DeserializationContext): MyObject {
val codec = jsonParser.codec
val tree = codec.readTree<JsonNode>(jsonParser)
val name = tree["name"].textValue()
val age = tree["age"].intValue()
return MyObject(name, age)
}
}
}
All @JsonComponent
beans in the ApplicationContext
are automatically registered with Jackson.
Because @JsonComponent
is meta-annotated with @Component
, the usual component-scanning rules apply.
Spring Boot also provides JsonObjectSerializer
and JsonObjectDeserializer
base classes that provide useful alternatives to the standard Jackson versions when serializing objects.
See JsonObjectSerializer
and JsonObjectDeserializer
in the Javadoc for details.
The example above can be rewritten to use JsonObjectSerializer
/JsonObjectDeserializer
as follows:
@JsonComponent
public class MyJsonComponent {
public static class Serializer extends JsonObjectSerializer<MyObject> {
@Override
protected void serializeObject(MyObject value, JsonGenerator jgen, SerializerProvider provider)
throws IOException {
jgen.writeStringField("name", value.getName());
jgen.writeNumberField("age", value.getAge());
}
}
public static class Deserializer extends JsonObjectDeserializer<MyObject> {
@Override
protected MyObject deserializeObject(JsonParser jsonParser, DeserializationContext context, ObjectCodec codec,
JsonNode tree) throws IOException {
String name = nullSafeValue(tree.get("name"), String.class);
int age = nullSafeValue(tree.get("age"), Integer.class);
return new MyObject(name, age);
}
}
}
`object`
@JsonComponent
class MyJsonComponent {
class Serializer : JsonObjectSerializer<MyObject>() {
@Throws(IOException::class)
override fun serializeObject(value: MyObject, jgen: JsonGenerator, provider: SerializerProvider) {
jgen.writeStringField("name", value.name)
jgen.writeNumberField("age", value.age)
}
}
class Deserializer : JsonObjectDeserializer<MyObject>() {
@Throws(IOException::class)
override fun deserializeObject(jsonParser: JsonParser, context: DeserializationContext,
codec: ObjectCodec, tree: JsonNode): MyObject {
val name = nullSafeValue(tree["name"], String::class.java)
val age = nullSafeValue(tree["age"], Int::class.java)
return MyObject(name, age)
}
}
}
Mixins
Jackson has support for mixins that can be used to mix additional annotations into those already declared on a target class.
Spring Boot’s Jackson auto-configuration will scan your application’s packages for classes annotated with @JsonMixin
and register them with the auto-configured ObjectMapper
.
The registration is performed by Spring Boot’s JsonMixinModule
.
7.8. Task Execution and Scheduling
In the absence of an Executor
bean in the context, Spring Boot auto-configures an AsyncTaskExecutor
.
When virtual threads are enabled (using Java 21+ and spring.threads.virtual.enabled
set to true
) this will be a SimpleAsyncTaskExecutor
that uses virtual threads.
Otherwise, it will be a ThreadPoolTaskExecutor
with sensible defaults.
In either case, the auto-configured executor will be automatically used for:
-
asynchronous task execution (
@EnableAsync
) -
Spring for GraphQL’s asynchronous handling of
Callable
return values from controller methods -
Spring MVC’s asynchronous request processing
-
Spring WebFlux’s blocking execution support
If you have defined a custom The auto-configured |
When a ThreadPoolTaskExecutor
is auto-configured, the thread pool uses 8 core threads that can grow and shrink according to the load.
Those default settings can be fine-tuned using the spring.task.execution
namespace, as shown in the following example:
spring.task.execution.pool.max-size=16
spring.task.execution.pool.queue-capacity=100
spring.task.execution.pool.keep-alive=10s
spring:
task:
execution:
pool:
max-size: 16
queue-capacity: 100
keep-alive: "10s"
This changes the thread pool to use a bounded queue so that when the queue is full (100 tasks), the thread pool increases to maximum 16 threads. Shrinking of the pool is more aggressive as threads are reclaimed when they are idle for 10 seconds (rather than 60 seconds by default).
A scheduler can also be auto-configured if it needs to be associated with scheduled task execution (using @EnableScheduling
for instance).
When virtual threads are enabled (using Java 21+ and spring.threads.virtual.enabled
set to true
) this will be a SimpleAsyncTaskScheduler
that uses virtual threads.
Otherwise, it will be a ThreadPoolTaskScheduler
with sensible defaults.
The ThreadPoolTaskScheduler
uses one thread by default and its settings can be fine-tuned using the spring.task.scheduling
namespace, as shown in the following example:
spring.task.scheduling.thread-name-prefix=scheduling-
spring.task.scheduling.pool.size=2
spring:
task:
scheduling:
thread-name-prefix: "scheduling-"
pool:
size: 2
A ThreadPoolTaskExecutorBuilder
bean, a SimpleAsyncTaskExecutorBuilder
bean, a ThreadPoolTaskSchedulerBuilder
bean and a SimpleAsyncTaskSchedulerBuilder
are made available in the context if a custom executor or scheduler needs to be created.
The SimpleAsyncTaskExecutorBuilder
and SimpleAsyncTaskSchedulerBuilder
beans are auto-configured to use virtual threads if they are enabled (using Java 21+ and spring.threads.virtual.enabled
set to true
).
7.9. Testing
Spring Boot provides a number of utilities and annotations to help when testing your application.
Test support is provided by two modules: spring-boot-test
contains core items, and spring-boot-test-autoconfigure
supports auto-configuration for tests.
Most developers use the spring-boot-starter-test
“Starter”, which imports both Spring Boot test modules as well as JUnit Jupiter, AssertJ, Hamcrest, and a number of other useful libraries.
If you have tests that use JUnit 4, JUnit 5’s vintage engine can be used to run them.
To use the vintage engine, add a dependency on
|
hamcrest-core
is excluded in favor of org.hamcrest:hamcrest
that is part of spring-boot-starter-test
.
7.9.1. Test Scope Dependencies
The spring-boot-starter-test
“Starter” (in the test
scope
) contains the following provided libraries:
-
JUnit 5: The de-facto standard for unit testing Java applications.
-
Spring Test & Spring Boot Test: Utilities and integration test support for Spring Boot applications.
-
AssertJ: A fluent assertion library.
-
Hamcrest: A library of matcher objects (also known as constraints or predicates).
-
Mockito: A Java mocking framework.
-
JSONassert: An assertion library for JSON.
-
JsonPath: XPath for JSON.
-
Awaitility: A library for testing asynchronous systems.
We generally find these common libraries to be useful when writing tests. If these libraries do not suit your needs, you can add additional test dependencies of your own.
7.9.2. Testing Spring Applications
One of the major advantages of dependency injection is that it should make your code easier to unit test.
You can instantiate objects by using the new
operator without even involving Spring.
You can also use mock objects instead of real dependencies.
Often, you need to move beyond unit testing and start integration testing (with a Spring ApplicationContext
).
It is useful to be able to perform integration testing without requiring deployment of your application or needing to connect to other infrastructure.
The Spring Framework includes a dedicated test module for such integration testing.
You can declare a dependency directly to org.springframework:spring-test
or use the spring-boot-starter-test
“Starter” to pull it in transitively.
If you have not used the spring-test
module before, you should start by reading the relevant section of the Spring Framework reference documentation.
7.9.3. Testing Spring Boot Applications
A Spring Boot application is a Spring ApplicationContext
, so nothing very special has to be done to test it beyond what you would normally do with a vanilla Spring context.
External properties, logging, and other features of Spring Boot are installed in the context by default only if you use SpringApplication to create it.
|
Spring Boot provides a @SpringBootTest
annotation, which can be used as an alternative to the standard spring-test
@ContextConfiguration
annotation when you need Spring Boot features.
The annotation works by creating the ApplicationContext
used in your tests through SpringApplication
.
In addition to @SpringBootTest
a number of other annotations are also provided for testing more specific slices of an application.
If you are using JUnit 4, do not forget to also add @RunWith(SpringRunner.class) to your test, otherwise the annotations will be ignored.
If you are using JUnit 5, there is no need to add the equivalent @ExtendWith(SpringExtension.class) as @SpringBootTest and the other @…Test annotations are already annotated with it.
|
By default, @SpringBootTest
will not start a server.
You can use the webEnvironment
attribute of @SpringBootTest
to further refine how your tests run:
-
MOCK
(Default) : Loads a webApplicationContext
and provides a mock web environment. Embedded servers are not started when using this annotation. If a web environment is not available on your classpath, this mode transparently falls back to creating a regular non-webApplicationContext
. It can be used in conjunction with@AutoConfigureMockMvc
or@AutoConfigureWebTestClient
for mock-based testing of your web application. -
RANDOM_PORT
: Loads aWebServerApplicationContext
and provides a real web environment. Embedded servers are started and listen on a random port. -
DEFINED_PORT
: Loads aWebServerApplicationContext
and provides a real web environment. Embedded servers are started and listen on a defined port (from yourapplication.properties
) or on the default port of8080
. -
NONE
: Loads anApplicationContext
by usingSpringApplication
but does not provide any web environment (mock or otherwise).
If your test is @Transactional , it rolls back the transaction at the end of each test method by default.
However, as using this arrangement with either RANDOM_PORT or DEFINED_PORT implicitly provides a real servlet environment, the HTTP client and server run in separate threads and, thus, in separate transactions.
Any transaction initiated on the server does not roll back in this case.
|
@SpringBootTest with webEnvironment = WebEnvironment.RANDOM_PORT will also start the management server on a separate random port if your application uses a different port for the management server.
|
Detecting Web Application Type
If Spring MVC is available, a regular MVC-based application context is configured. If you have only Spring WebFlux, we will detect that and configure a WebFlux-based application context instead.
If both are present, Spring MVC takes precedence.
If you want to test a reactive web application in this scenario, you must set the spring.main.web-application-type
property:
@SpringBootTest(properties = "spring.main.web-application-type=reactive")
class MyWebFluxTests {
// ...
}
@SpringBootTest(properties = ["spring.main.web-application-type=reactive"])
class MyWebFluxTests {
// ...
}
Detecting Test Configuration
If you are familiar with the Spring Test Framework, you may be used to using @ContextConfiguration(classes=…)
in order to specify which Spring @Configuration
to load.
Alternatively, you might have often used nested @Configuration
classes within your test.
When testing Spring Boot applications, this is often not required.
Spring Boot’s @*Test
annotations search for your primary configuration automatically whenever you do not explicitly define one.
The search algorithm works up from the package that contains the test until it finds a class annotated with @SpringBootApplication
or @SpringBootConfiguration
.
As long as you structured your code in a sensible way, your main configuration is usually found.
If you use a test annotation to test a more specific slice of your application, you should avoid adding configuration settings that are specific to a particular area on the main method’s application class. The underlying component scan configuration of |
If you want to customize the primary configuration, you can use a nested @TestConfiguration
class.
Unlike a nested @Configuration
class, which would be used instead of your application’s primary configuration, a nested @TestConfiguration
class is used in addition to your application’s primary configuration.
Spring’s test framework caches application contexts between tests. Therefore, as long as your tests share the same configuration (no matter how it is discovered), the potentially time-consuming process of loading the context happens only once. |
Using the Test Configuration Main Method
Typically the test configuration discovered by @SpringBootTest
will be your main @SpringBootApplication
.
In most well structured applications, this configuration class will also include the main
method used to launch the application.
For example, the following is a very common code pattern for a typical Spring Boot application:
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
@SpringBootApplication
class MyApplication
fun main(args: Array<String>) {
runApplication<MyApplication>(*args)
}
In the example above, the main
method doesn’t do anything other than delegate to SpringApplication.run
.
It is, however, possible to have a more complex main
method that applies customizations before calling SpringApplication.run
.
For example, here is an application that changes the banner mode and sets additional profiles:
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
SpringApplication application = new SpringApplication(MyApplication.class);
application.setBannerMode(Banner.Mode.OFF);
application.setAdditionalProfiles("myprofile");
application.run(args);
}
}
@SpringBootApplication
class MyApplication
fun main(args: Array<String>) {
runApplication<MyApplication>(*args) {
setBannerMode(Banner.Mode.OFF)
setAdditionalProfiles("myprofile");
}
}
Since customizations in the main
method can affect the resulting ApplicationContext
, it’s possible that you might also want to use the main
method to create the ApplicationContext
used in your tests.
By default, @SpringBootTest
will not call your main
method, and instead the class itself is used directly to create the ApplicationContext
If you want to change this behavior, you can change the useMainMethod
attribute of @SpringBootTest
to UseMainMethod.ALWAYS
or UseMainMethod.WHEN_AVAILABLE
.
When set to ALWAYS
, the test will fail if no main
method can be found.
When set to WHEN_AVAILABLE
the main
method will be used if it is available, otherwise the standard loading mechanism will be used.
For example, the following test will invoke the main
method of MyApplication
in order to create the ApplicationContext
.
If the main method sets additional profiles then those will be active when the ApplicationContext
starts.
@SpringBootTest(useMainMethod = UseMainMethod.ALWAYS)
class MyApplicationTests {
@Test
void exampleTest() {
// ...
}
}
@SpringBootTest(useMainMethod = UseMainMethod.ALWAYS)
class MyApplicationTests {
@Test
fun exampleTest() {
// ...
}
}
Excluding Test Configuration
If your application uses component scanning (for example, if you use @SpringBootApplication
or @ComponentScan
), you may find top-level configuration classes that you created only for specific tests accidentally get picked up everywhere.
As we have seen earlier, @TestConfiguration
can be used on an inner class of a test to customize the primary configuration.
@TestConfiguration
can also be used on a top-level class. Doing so indicates that the class should not be picked up by scanning.
You can then import the class explicitly where it is required, as shown in the following example:
@SpringBootTest
@Import(MyTestsConfiguration.class)
class MyTests {
@Test
void exampleTest() {
// ...
}
}
@SpringBootTest
@Import(MyTestsConfiguration::class)
class MyTests {
@Test
fun exampleTest() {
// ...
}
}
If you directly use @ComponentScan (that is, not through @SpringBootApplication ) you need to register the TypeExcludeFilter with it.
See the Javadoc for details.
|
An imported @TestConfiguration is processed earlier than an inner-class @TestConfiguration and an imported @TestConfiguration will be processed before any configuration found through component scanning.
Generally speaking, this difference in ordering has no noticeable effect but it is something to be aware of if you’re relying on bean overriding.
|
Using Application Arguments
If your application expects arguments, you can
have @SpringBootTest
inject them using the args
attribute.
@SpringBootTest(args = "--app.test=one")
class MyApplicationArgumentTests {
@Test
void applicationArgumentsPopulated(@Autowired ApplicationArguments args) {
assertThat(args.getOptionNames()).containsOnly("app.test");
assertThat(args.getOptionValues("app.test")).containsOnly("one");
}
}
@SpringBootTest(args = ["--app.test=one"])
class MyApplicationArgumentTests {
@Test
fun applicationArgumentsPopulated(@Autowired args: ApplicationArguments) {
assertThat(args.optionNames).containsOnly("app.test")
assertThat(args.getOptionValues("app.test")).containsOnly("one")
}
}
Testing With a Mock Environment
By default, @SpringBootTest
does not start the server but instead sets up a mock environment for testing web endpoints.
With Spring MVC, we can query our web endpoints using MockMvc
or WebTestClient
, as shown in the following example:
@SpringBootTest
@AutoConfigureMockMvc
class MyMockMvcTests {
@Test
void testWithMockMvc(@Autowired MockMvc mvc) throws Exception {
mvc.perform(get("/")).andExpect(status().isOk()).andExpect(content().string("Hello World"));
}
// If Spring WebFlux is on the classpath, you can drive MVC tests with a WebTestClient
@Test
void testWithWebTestClient(@Autowired WebTestClient webClient) {
webClient
.get().uri("/")
.exchange()
.expectStatus().isOk()
.expectBody(String.class).isEqualTo("Hello World");
}
}
@SpringBootTest
@AutoConfigureMockMvc
class MyMockMvcTests {
@Test
fun testWithMockMvc(@Autowired mvc: MockMvc) {
mvc.perform(MockMvcRequestBuilders.get("/")).andExpect(MockMvcResultMatchers.status().isOk)
.andExpect(MockMvcResultMatchers.content().string("Hello World"))
}
// If Spring WebFlux is on the classpath, you can drive MVC tests with a WebTestClient
@Test
fun testWithWebTestClient(@Autowired webClient: WebTestClient) {
webClient
.get().uri("/")
.exchange()
.expectStatus().isOk
.expectBody<String>().isEqualTo("Hello World")
}
}
If you want to focus only on the web layer and not start a complete ApplicationContext , consider using @WebMvcTest instead.
|
With Spring WebFlux endpoints, you can use WebTestClient
as shown in the following example:
@SpringBootTest
@AutoConfigureWebTestClient
class MyMockWebTestClientTests {
@Test
void exampleTest(@Autowired WebTestClient webClient) {
webClient
.get().uri("/")
.exchange()
.expectStatus().isOk()
.expectBody(String.class).isEqualTo("Hello World");
}
}
@SpringBootTest
@AutoConfigureWebTestClient
class MyMockWebTestClientTests {
@Test
fun exampleTest(@Autowired webClient: WebTestClient) {
webClient
.get().uri("/")
.exchange()
.expectStatus().isOk
.expectBody<String>().isEqualTo("Hello World")
}
}
Testing within a mocked environment is usually faster than running with a full servlet container. However, since mocking occurs at the Spring MVC layer, code that relies on lower-level servlet container behavior cannot be directly tested with MockMvc. For example, Spring Boot’s error handling is based on the “error page” support provided by the servlet container. This means that, whilst you can test your MVC layer throws and handles exceptions as expected, you cannot directly test that a specific custom error page is rendered. If you need to test these lower-level concerns, you can start a fully running server as described in the next section. |
Testing With a Running Server
If you need to start a full running server, we recommend that you use random ports.
If you use @SpringBootTest(webEnvironment=WebEnvironment.RANDOM_PORT)
, an available port is picked at random each time your test runs.
The @LocalServerPort
annotation can be used to inject the actual port used into your test.
For convenience, tests that need to make REST calls to the started server can additionally @Autowire
a WebTestClient
, which resolves relative links to the running server and comes with a dedicated API for verifying responses, as shown in the following example:
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class MyRandomPortWebTestClientTests {
@Test
void exampleTest(@Autowired WebTestClient webClient) {
webClient
.get().uri("/")
.exchange()
.expectStatus().isOk()
.expectBody(String.class).isEqualTo("Hello World");
}
}
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class MyRandomPortWebTestClientTests {
@Test
fun exampleTest(@Autowired webClient: WebTestClient) {
webClient
.get().uri("/")
.exchange()
.expectStatus().isOk
.expectBody<String>().isEqualTo("Hello World")
}
}
WebTestClient can also used with a mock environment, removing the need for a running server, by annotating your test class with @AutoConfigureWebTestClient .
|
This setup requires spring-webflux
on the classpath.
If you can not or will not add webflux, Spring Boot also provides a TestRestTemplate
facility:
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class MyRandomPortTestRestTemplateTests {
@Test
void exampleTest(@Autowired TestRestTemplate restTemplate) {
String body = restTemplate.getForObject("/", String.class);
assertThat(body).isEqualTo("Hello World");
}
}
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class MyRandomPortTestRestTemplateTests {
@Test
fun exampleTest(@Autowired restTemplate: TestRestTemplate) {
val body = restTemplate.getForObject("/", String::class.java)
assertThat(body).isEqualTo("Hello World")
}
}
Customizing WebTestClient
To customize the WebTestClient
bean, configure a WebTestClientBuilderCustomizer
bean.
Any such beans are called with the WebTestClient.Builder
that is used to create the WebTestClient
.
Using JMX
As the test context framework caches context, JMX is disabled by default to prevent identical components to register on the same domain.
If such test needs access to an MBeanServer
, consider marking it dirty as well:
@SpringBootTest(properties = "spring.jmx.enabled=true")
@DirtiesContext
class MyJmxTests {
@Autowired
private MBeanServer mBeanServer;
@Test
void exampleTest() {
assertThat(this.mBeanServer.getDomains()).contains("java.lang");
// ...
}
}
@SpringBootTest(properties = ["spring.jmx.enabled=true"])
@DirtiesContext
class MyJmxTests(@Autowired val mBeanServer: MBeanServer) {
@Test
fun exampleTest() {
assertThat(mBeanServer.domains).contains("java.lang")
// ...
}
}
Using Metrics
Regardless of your classpath, meter registries, except the in-memory backed, are not auto-configured when using @SpringBootTest
.
If you need to export metrics to a different backend as part of an integration test, annotate it with @AutoConfigureObservability
.
Using Tracing
Regardless of your classpath, tracing components which are reporting data are not auto-configured when using @SpringBootTest
.
If you need those components as part of an integration test, annotate the test with @AutoConfigureObservability
.
If you have created your own reporting components (e.g. a custom SpanExporter
or SpanHandler
) and you don’t want them to be active in tests, you can use the @ConditionalOnEnabledTracing
annotation to disable them.
Mocking and Spying Beans
When running tests, it is sometimes necessary to mock certain components within your application context. For example, you may have a facade over some remote service that is unavailable during development. Mocking can also be useful when you want to simulate failures that might be hard to trigger in a real environment.
Spring Boot includes a @MockBean
annotation that can be used to define a Mockito mock for a bean inside your ApplicationContext
.
You can use the annotation to add new beans or replace a single existing bean definition.
The annotation can be used directly on test classes, on fields within your test, or on @Configuration
classes and fields.
When used on a field, the instance of the created mock is also injected.
Mock beans are automatically reset after each test method.
If your test uses one of Spring Boot’s test annotations (such as Java
Kotlin
|
The following example replaces an existing RemoteService
bean with a mock implementation:
@SpringBootTest
class MyTests {
@Autowired
private Reverser reverser;
@MockBean
private RemoteService remoteService;
@Test
void exampleTest() {
given(this.remoteService.getValue()).willReturn("spring");
String reverse = this.reverser.getReverseValue(); // Calls injected RemoteService
assertThat(reverse).isEqualTo("gnirps");
}
}
@SpringBootTest
class MyTests(@Autowired val reverser: Reverser, @MockBean val remoteService: RemoteService) {
@Test
fun exampleTest() {
given(remoteService.value).willReturn("spring")
val reverse = reverser.reverseValue // Calls injected RemoteService
assertThat(reverse).isEqualTo("gnirps")
}
}
@MockBean cannot be used to mock the behavior of a bean that is exercised during application context refresh.
By the time the test is executed, the application context refresh has completed and it is too late to configure the mocked behavior.
We recommend using a @Bean method to create and configure the mock in this situation.
|
Additionally, you can use @SpyBean
to wrap any existing bean with a Mockito spy
.
See the Javadoc for full details.
While Spring’s test framework caches application contexts between tests and reuses a context for tests sharing the same configuration, the use of @MockBean or @SpyBean influences the cache key, which will most likely increase the number of contexts.
|
If you are using @SpyBean to spy on a bean with @Cacheable methods that refer to parameters by name, your application must be compiled with -parameters .
This ensures that the parameter names are available to the caching infrastructure once the bean has been spied upon.
|
When you are using @SpyBean to spy on a bean that is proxied by Spring, you may need to remove Spring’s proxy in some situations, for example when setting expectations using given or when .
Use AopTestUtils.getTargetObject(yourProxiedSpy) to do so.
|
Auto-configured Tests
Spring Boot’s auto-configuration system works well for applications but can sometimes be a little too much for tests. It often helps to load only the parts of the configuration that are required to test a “slice” of your application. For example, you might want to test that Spring MVC controllers are mapping URLs correctly, and you do not want to involve database calls in those tests, or you might want to test JPA entities, and you are not interested in the web layer when those tests run.
The spring-boot-test-autoconfigure
module includes a number of annotations that can be used to automatically configure such “slices”.
Each of them works in a similar way, providing a @…Test
annotation that loads the ApplicationContext
and one or more @AutoConfigure…
annotations that can be used to customize auto-configuration settings.
Each slice restricts component scan to appropriate components and loads a very restricted set of auto-configuration classes.
If you need to exclude one of them, most @…Test annotations provide an excludeAutoConfiguration attribute.
Alternatively, you can use @ImportAutoConfiguration#exclude .
|
Including multiple “slices” by using several @…Test annotations in one test is not supported.
If you need multiple “slices”, pick one of the @…Test annotations and include the @AutoConfigure… annotations of the other “slices” by hand.
|
It is also possible to use the @AutoConfigure… annotations with the standard @SpringBootTest annotation.
You can use this combination if you are not interested in “slicing” your application but you want some of the auto-configured test beans.
|
Auto-configured JSON Tests
To test that object JSON serialization and deserialization is working as expected, you can use the @JsonTest
annotation.
@JsonTest
auto-configures the available supported JSON mapper, which can be one of the following libraries:
-
Jackson
ObjectMapper
, any@JsonComponent
beans and any JacksonModule
s -
Gson
-
Jsonb
A list of the auto-configurations that are enabled by @JsonTest can be found in the appendix.
|
If you need to configure elements of the auto-configuration, you can use the @AutoConfigureJsonTesters
annotation.
Spring Boot includes AssertJ-based helpers that work with the JSONAssert and JsonPath libraries to check that JSON appears as expected.
The JacksonTester
, GsonTester
, JsonbTester
, and BasicJsonTester
classes can be used for Jackson, Gson, Jsonb, and Strings respectively.
Any helper fields on the test class can be @Autowired
when using @JsonTest
.
The following example shows a test class for Jackson:
@JsonTest
class MyJsonTests {
@Autowired
private JacksonTester<VehicleDetails> json;
@Test
void serialize() throws Exception {
VehicleDetails details = new VehicleDetails("Honda", "Civic");
// Assert against a `.json` file in the same package as the test
assertThat(this.json.write(details)).isEqualToJson("expected.json");
// Or use JSON path based assertions
assertThat(this.json.write(details)).hasJsonPathStringValue("@.make");
assertThat(this.json.write(details)).extractingJsonPathStringValue("@.make").isEqualTo("Honda");
}
@Test
void deserialize() throws Exception {
String content = "{\"make\":\"Ford\",\"model\":\"Focus\"}";
assertThat(this.json.parse(content)).isEqualTo(new VehicleDetails("Ford", "Focus"));
assertThat(this.json.parseObject(content).getMake()).isEqualTo("Ford");
}
}
@JsonTest
class MyJsonTests(@Autowired val json: JacksonTester<VehicleDetails>) {
@Test
fun serialize() {
val details = VehicleDetails("Honda", "Civic")
// Assert against a `.json` file in the same package as the test
assertThat(json.write(details)).isEqualToJson("expected.json")
// Or use JSON path based assertions
assertThat(json.write(details)).hasJsonPathStringValue("@.make")
assertThat(json.write(details)).extractingJsonPathStringValue("@.make").isEqualTo("Honda")
}
@Test
fun deserialize() {
val content = "{\"make\":\"Ford\",\"model\":\"Focus\"}"
assertThat(json.parse(content)).isEqualTo(VehicleDetails("Ford", "Focus"))
assertThat(json.parseObject(content).make).isEqualTo("Ford")
}
}
JSON helper classes can also be used directly in standard unit tests.
To do so, call the initFields method of the helper in your @Before method if you do not use @JsonTest .
|
If you use Spring Boot’s AssertJ-based helpers to assert on a number value at a given JSON path, you might not be able to use isEqualTo
depending on the type.
Instead, you can use AssertJ’s satisfies
to assert that the value matches the given condition.
For instance, the following example asserts that the actual number is a float value close to 0.15
within an offset of 0.01
.
@Test
void someTest() throws Exception {
SomeObject value = new SomeObject(0.152f);
assertThat(this.json.write(value)).extractingJsonPathNumberValue("@.test.numberValue")
.satisfies((number) -> assertThat(number.floatValue()).isCloseTo(0.15f, within(0.01f)));
}
@Test
fun someTest() {
val value = SomeObject(0.152f)
assertThat(json.write(value)).extractingJsonPathNumberValue("@.test.numberValue")
.satisfies(ThrowingConsumer { number ->
assertThat(number.toFloat()).isCloseTo(0.15f, within(0.01f))
})
}
Auto-configured Spring MVC Tests
To test whether Spring MVC controllers are working as expected, use the @WebMvcTest
annotation.
@WebMvcTest
auto-configures the Spring MVC infrastructure and limits scanned beans to @Controller
, @ControllerAdvice
, @JsonComponent
, Converter
, GenericConverter
, Filter
, HandlerInterceptor
, WebMvcConfigurer
, WebMvcRegistrations
, and HandlerMethodArgumentResolver
.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @WebMvcTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
A list of the auto-configuration settings that are enabled by @WebMvcTest can be found in the appendix.
|
If you need to register extra components, such as the Jackson Module , you can import additional configuration classes by using @Import on your test.
|
Often, @WebMvcTest
is limited to a single controller and is used in combination with @MockBean
to provide mock implementations for required collaborators.
@WebMvcTest
also auto-configures MockMvc
.
Mock MVC offers a powerful way to quickly test MVC controllers without needing to start a full HTTP server.
You can also auto-configure MockMvc in a non-@WebMvcTest (such as @SpringBootTest ) by annotating it with @AutoConfigureMockMvc .
The following example uses MockMvc :
|
@WebMvcTest(UserVehicleController.class)
class MyControllerTests {
@Autowired
private MockMvc mvc;
@MockBean
private UserVehicleService userVehicleService;
@Test
void testExample() throws Exception {
given(this.userVehicleService.getVehicleDetails("sboot"))
.willReturn(new VehicleDetails("Honda", "Civic"));
this.mvc.perform(get("/sboot/vehicle").accept(MediaType.TEXT_PLAIN))
.andExpect(status().isOk())
.andExpect(content().string("Honda Civic"));
}
}
@WebMvcTest(UserVehicleController::class)
class MyControllerTests(@Autowired val mvc: MockMvc) {
@MockBean
lateinit var userVehicleService: UserVehicleService
@Test
fun testExample() {
given(userVehicleService.getVehicleDetails("sboot"))
.willReturn(VehicleDetails("Honda", "Civic"))
mvc.perform(MockMvcRequestBuilders.get("/sboot/vehicle").accept(MediaType.TEXT_PLAIN))
.andExpect(MockMvcResultMatchers.status().isOk)
.andExpect(MockMvcResultMatchers.content().string("Honda Civic"))
}
}
If you need to configure elements of the auto-configuration (for example, when servlet filters should be applied) you can use attributes in the @AutoConfigureMockMvc annotation.
|
If you use HtmlUnit and Selenium, auto-configuration also provides an HtmlUnit WebClient
bean and/or a Selenium WebDriver
bean.
The following example uses HtmlUnit:
@WebMvcTest(UserVehicleController.class)
class MyHtmlUnitTests {
@Autowired
private WebClient webClient;
@MockBean
private UserVehicleService userVehicleService;
@Test
void testExample() throws Exception {
given(this.userVehicleService.getVehicleDetails("sboot")).willReturn(new VehicleDetails("Honda", "Civic"));
HtmlPage page = this.webClient.getPage("/sboot/vehicle.html");
assertThat(page.getBody().getTextContent()).isEqualTo("Honda Civic");
}
}
@WebMvcTest(UserVehicleController::class)
class MyHtmlUnitTests(@Autowired val webClient: WebClient) {
@MockBean
lateinit var userVehicleService: UserVehicleService
@Test
fun testExample() {
given(userVehicleService.getVehicleDetails("sboot")).willReturn(VehicleDetails("Honda", "Civic"))
val page = webClient.getPage<HtmlPage>("/sboot/vehicle.html")
assertThat(page.body.textContent).isEqualTo("Honda Civic")
}
}
By default, Spring Boot puts WebDriver beans in a special “scope” to ensure that the driver exits after each test and that a new instance is injected.
If you do not want this behavior, you can add @Scope("singleton") to your WebDriver @Bean definition.
|
The webDriver scope created by Spring Boot will replace any user defined scope of the same name.
If you define your own webDriver scope you may find it stops working when you use @WebMvcTest .
|
If you have Spring Security on the classpath, @WebMvcTest
will also scan WebSecurityConfigurer
beans.
Instead of disabling security completely for such tests, you can use Spring Security’s test support.
More details on how to use Spring Security’s MockMvc
support can be found in this Testing With Spring Security how-to section.
Sometimes writing Spring MVC tests is not enough; Spring Boot can help you run full end-to-end tests with an actual server. |
Auto-configured Spring WebFlux Tests
To test that Spring WebFlux controllers are working as expected, you can use the @WebFluxTest
annotation.
@WebFluxTest
auto-configures the Spring WebFlux infrastructure and limits scanned beans to @Controller
, @ControllerAdvice
, @JsonComponent
, Converter
, GenericConverter
, WebFilter
, and WebFluxConfigurer
.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @WebFluxTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
A list of the auto-configurations that are enabled by @WebFluxTest can be found in the appendix.
|
If you need to register extra components, such as Jackson Module , you can import additional configuration classes using @Import on your test.
|
Often, @WebFluxTest
is limited to a single controller and used in combination with the @MockBean
annotation to provide mock implementations for required collaborators.
@WebFluxTest
also auto-configures WebTestClient
, which offers a powerful way to quickly test WebFlux controllers without needing to start a full HTTP server.
You can also auto-configure WebTestClient in a non-@WebFluxTest (such as @SpringBootTest ) by annotating it with @AutoConfigureWebTestClient .
The following example shows a class that uses both @WebFluxTest and a WebTestClient :
|
@WebFluxTest(UserVehicleController.class)
class MyControllerTests {
@Autowired
private WebTestClient webClient;
@MockBean
private UserVehicleService userVehicleService;
@Test
void testExample() {
given(this.userVehicleService.getVehicleDetails("sboot"))
.willReturn(new VehicleDetails("Honda", "Civic"));
this.webClient.get().uri("/sboot/vehicle").accept(MediaType.TEXT_PLAIN).exchange()
.expectStatus().isOk()
.expectBody(String.class).isEqualTo("Honda Civic");
}
}
@WebFluxTest(UserVehicleController::class)
class MyControllerTests(@Autowired val webClient: WebTestClient) {
@MockBean
lateinit var userVehicleService: UserVehicleService
@Test
fun testExample() {
given(userVehicleService.getVehicleDetails("sboot"))
.willReturn(VehicleDetails("Honda", "Civic"))
webClient.get().uri("/sboot/vehicle").accept(MediaType.TEXT_PLAIN).exchange()
.expectStatus().isOk
.expectBody<String>().isEqualTo("Honda Civic")
}
}
This setup is only supported by WebFlux applications as using WebTestClient in a mocked web application only works with WebFlux at the moment.
|
@WebFluxTest cannot detect routes registered through the functional web framework.
For testing RouterFunction beans in the context, consider importing your RouterFunction yourself by using @Import or by using @SpringBootTest .
|
@WebFluxTest cannot detect custom security configuration registered as a @Bean of type SecurityWebFilterChain .
To include that in your test, you will need to import the configuration that registers the bean by using @Import or by using @SpringBootTest .
|
Sometimes writing Spring WebFlux tests is not enough; Spring Boot can help you run full end-to-end tests with an actual server. |
Auto-configured Spring GraphQL Tests
Spring GraphQL offers a dedicated testing support module; you’ll need to add it to your project:
<dependencies>
<dependency>
<groupId>org.springframework.graphql</groupId>
<artifactId>spring-graphql-test</artifactId>
<scope>test</scope>
</dependency>
<!-- Unless already present in the compile scope -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
dependencies {
testImplementation("org.springframework.graphql:spring-graphql-test")
// Unless already present in the implementation configuration
testImplementation("org.springframework.boot:spring-boot-starter-webflux")
}
This testing module ships the GraphQlTester.
The tester is heavily used in test, so be sure to become familiar with using it.
There are GraphQlTester
variants and Spring Boot will auto-configure them depending on the type of tests:
-
the
ExecutionGraphQlServiceTester
performs tests on the server side, without a client nor a transport -
the
HttpGraphQlTester
performs tests with a client that connects to a server, with or without a live server
Spring Boot helps you to test your Spring GraphQL Controllers with the @GraphQlTest
annotation.
@GraphQlTest
auto-configures the Spring GraphQL infrastructure, without any transport nor server being involved.
This limits scanned beans to @Controller
, RuntimeWiringConfigurer
, JsonComponent
, Converter
, GenericConverter
, DataFetcherExceptionResolver
, Instrumentation
and GraphQlSourceBuilderCustomizer
.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @GraphQlTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
A list of the auto-configurations that are enabled by @GraphQlTest can be found in the appendix.
|
Often, @GraphQlTest
is limited to a set of controllers and used in combination with the @MockBean
annotation to provide mock implementations for required collaborators.
@GraphQlTest(GreetingController.class)
class GreetingControllerTests {
@Autowired
private GraphQlTester graphQlTester;
@Test
void shouldGreetWithSpecificName() {
this.graphQlTester.document("{ greeting(name: \"Alice\") } ")
.execute()
.path("greeting")
.entity(String.class)
.isEqualTo("Hello, Alice!");
}
@Test
void shouldGreetWithDefaultName() {
this.graphQlTester.document("{ greeting } ")
.execute()
.path("greeting")
.entity(String.class)
.isEqualTo("Hello, Spring!");
}
}
@GraphQlTest(GreetingController::class)
internal class GreetingControllerTests {
@Autowired
lateinit var graphQlTester: GraphQlTester
@Test
fun shouldGreetWithSpecificName() {
graphQlTester.document("{ greeting(name: \"Alice\") } ").execute().path("greeting").entity(String::class.java)
.isEqualTo("Hello, Alice!")
}
@Test
fun shouldGreetWithDefaultName() {
graphQlTester.document("{ greeting } ").execute().path("greeting").entity(String::class.java)
.isEqualTo("Hello, Spring!")
}
}
@SpringBootTest
tests are full integration tests and involve the entire application.
When using a random or defined port, a live server is configured and an HttpGraphQlTester
bean is contributed automatically so you can use it to test your server.
When a MOCK environment is configured, you can also request an HttpGraphQlTester
bean by annotating your test class with @AutoConfigureHttpGraphQlTester
:
@AutoConfigureHttpGraphQlTester
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.MOCK)
class GraphQlIntegrationTests {
@Test
void shouldGreetWithSpecificName(@Autowired HttpGraphQlTester graphQlTester) {
HttpGraphQlTester authenticatedTester = graphQlTester.mutate()
.webTestClient((client) -> client.defaultHeaders((headers) -> headers.setBasicAuth("admin", "ilovespring")))
.build();
authenticatedTester.document("{ greeting(name: \"Alice\") } ")
.execute()
.path("greeting")
.entity(String.class)
.isEqualTo("Hello, Alice!");
}
}
@AutoConfigureHttpGraphQlTester
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.MOCK)
class GraphQlIntegrationTests {
@Test
fun shouldGreetWithSpecificName(@Autowired graphQlTester: HttpGraphQlTester) {
val authenticatedTester = graphQlTester.mutate()
.webTestClient { client: WebTestClient.Builder ->
client.defaultHeaders { headers: HttpHeaders ->
headers.setBasicAuth("admin", "ilovespring")
}
}.build()
authenticatedTester.document("{ greeting(name: \"Alice\") } ").execute()
.path("greeting").entity(String::class.java).isEqualTo("Hello, Alice!")
}
}
Auto-configured Data Cassandra Tests
You can use @DataCassandraTest
to test Cassandra applications.
By default, it configures a CassandraTemplate
, scans for @Table
classes, and configures Spring Data Cassandra repositories.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @DataCassandraTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
(For more about using Cassandra with Spring Boot, see "Cassandra".)
A list of the auto-configuration settings that are enabled by @DataCassandraTest can be found in the appendix.
|
The following example shows a typical setup for using Cassandra tests in Spring Boot:
@DataCassandraTest
class MyDataCassandraTests {
@Autowired
private SomeRepository repository;
}
@DataCassandraTest
class MyDataCassandraTests(@Autowired val repository: SomeRepository)
Auto-configured Data Couchbase Tests
You can use @DataCouchbaseTest
to test Couchbase applications.
By default, it configures a CouchbaseTemplate
or ReactiveCouchbaseTemplate
, scans for @Document
classes, and configures Spring Data Couchbase repositories.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @DataCouchbaseTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
(For more about using Couchbase with Spring Boot, see "Couchbase", earlier in this chapter.)
A list of the auto-configuration settings that are enabled by @DataCouchbaseTest can be found in the appendix.
|
The following example shows a typical setup for using Couchbase tests in Spring Boot:
@DataCouchbaseTest
class MyDataCouchbaseTests {
@Autowired
private SomeRepository repository;
// ...
}
@DataCouchbaseTest
class MyDataCouchbaseTests(@Autowired val repository: SomeRepository) {
// ...
}
Auto-configured Data Elasticsearch Tests
You can use @DataElasticsearchTest
to test Elasticsearch applications.
By default, it configures an ElasticsearchRestTemplate
, scans for @Document
classes, and configures Spring Data Elasticsearch repositories.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @DataElasticsearchTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
(For more about using Elasticsearch with Spring Boot, see "Elasticsearch", earlier in this chapter.)
A list of the auto-configuration settings that are enabled by @DataElasticsearchTest can be found in the appendix.
|
The following example shows a typical setup for using Elasticsearch tests in Spring Boot:
@DataElasticsearchTest
class MyDataElasticsearchTests {
@Autowired
private SomeRepository repository;
// ...
}
@DataElasticsearchTest
class MyDataElasticsearchTests(@Autowired val repository: SomeRepository) {
// ...
}
Auto-configured Data JPA Tests
You can use the @DataJpaTest
annotation to test JPA applications.
By default, it scans for @Entity
classes and configures Spring Data JPA repositories.
If an embedded database is available on the classpath, it configures one as well.
SQL queries are logged by default by setting the spring.jpa.show-sql
property to true
.
This can be disabled using the showSql
attribute of the annotation.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @DataJpaTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
A list of the auto-configuration settings that are enabled by @DataJpaTest can be found in the appendix.
|
By default, data JPA tests are transactional and roll back at the end of each test. See the relevant section in the Spring Framework Reference Documentation for more details. If that is not what you want, you can disable transaction management for a test or for the whole class as follows:
@DataJpaTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class MyNonTransactionalTests {
// ...
}
@DataJpaTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class MyNonTransactionalTests {
// ...
}
Data JPA tests may also inject a TestEntityManager
bean, which provides an alternative to the standard JPA EntityManager
that is specifically designed for tests.
TestEntityManager can also be auto-configured to any of your Spring-based test class by adding @AutoConfigureTestEntityManager .
When doing so, make sure that your test is running in a transaction, for instance by adding @Transactional on your test class or method.
|
A JdbcTemplate
is also available if you need that.
The following example shows the @DataJpaTest
annotation in use:
@DataJpaTest
class MyRepositoryTests {
@Autowired
private TestEntityManager entityManager;
@Autowired
private UserRepository repository;
@Test
void testExample() {
this.entityManager.persist(new User("sboot", "1234"));
User user = this.repository.findByUsername("sboot");
assertThat(user.getUsername()).isEqualTo("sboot");
assertThat(user.getEmployeeNumber()).isEqualTo("1234");
}
}
@DataJpaTest
class MyRepositoryTests(@Autowired val entityManager: TestEntityManager, @Autowired val repository: UserRepository) {
@Test
fun testExample() {
entityManager.persist(User("sboot", "1234"))
val user = repository.findByUsername("sboot")
assertThat(user?.username).isEqualTo("sboot")
assertThat(user?.employeeNumber).isEqualTo("1234")
}
}
In-memory embedded databases generally work well for tests, since they are fast and do not require any installation.
If, however, you prefer to run tests against a real database you can use the @AutoConfigureTestDatabase
annotation, as shown in the following example:
@DataJpaTest
@AutoConfigureTestDatabase(replace = Replace.NONE)
class MyRepositoryTests {
// ...
}
@DataJpaTest
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
class MyRepositoryTests {
// ...
}
Auto-configured JDBC Tests
@JdbcTest
is similar to @DataJpaTest
but is for tests that only require a DataSource
and do not use Spring Data JDBC.
By default, it configures an in-memory embedded database and a JdbcTemplate
.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @JdbcTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
A list of the auto-configurations that are enabled by @JdbcTest can be found in the appendix.
|
By default, JDBC tests are transactional and roll back at the end of each test. See the relevant section in the Spring Framework Reference Documentation for more details. If that is not what you want, you can disable transaction management for a test or for the whole class, as follows:
@JdbcTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class MyTransactionalTests {
}
@JdbcTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class MyTransactionalTests
If you prefer your test to run against a real database, you can use the @AutoConfigureTestDatabase
annotation in the same way as for @DataJpaTest
.
(See "Auto-configured Data JPA Tests".)
Auto-configured Data JDBC Tests
@DataJdbcTest
is similar to @JdbcTest
but is for tests that use Spring Data JDBC repositories.
By default, it configures an in-memory embedded database, a JdbcTemplate
, and Spring Data JDBC repositories.
Only AbstractJdbcConfiguration
subclasses are scanned when the @DataJdbcTest
annotation is used, regular @Component
and @ConfigurationProperties
beans are not scanned.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
A list of the auto-configurations that are enabled by @DataJdbcTest can be found in the appendix.
|
By default, Data JDBC tests are transactional and roll back at the end of each test. See the relevant section in the Spring Framework Reference Documentation for more details. If that is not what you want, you can disable transaction management for a test or for the whole test class as shown in the JDBC example.
If you prefer your test to run against a real database, you can use the @AutoConfigureTestDatabase
annotation in the same way as for @DataJpaTest
.
(See "Auto-configured Data JPA Tests".)
Auto-configured Data R2DBC Tests
@DataR2dbcTest
is similar to @DataJdbcTest
but is for tests that use Spring Data R2DBC repositories.
By default, it configures an in-memory embedded database, an R2dbcEntityTemplate
, and Spring Data R2DBC repositories.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @DataR2dbcTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
A list of the auto-configurations that are enabled by @DataR2dbcTest can be found in the appendix.
|
By default, Data R2DBC tests are not transactional.
If you prefer your test to run against a real database, you can use the @AutoConfigureTestDatabase
annotation in the same way as for @DataJpaTest
.
(See "Auto-configured Data JPA Tests".)
Auto-configured jOOQ Tests
You can use @JooqTest
in a similar fashion as @JdbcTest
but for jOOQ-related tests.
As jOOQ relies heavily on a Java-based schema that corresponds with the database schema, the existing DataSource
is used.
If you want to replace it with an in-memory database, you can use @AutoConfigureTestDatabase
to override those settings.
(For more about using jOOQ with Spring Boot, see "Using jOOQ".)
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @JooqTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
A list of the auto-configurations that are enabled by @JooqTest can be found in the appendix.
|
@JooqTest
configures a DSLContext
.
The following example shows the @JooqTest
annotation in use:
@JooqTest
class MyJooqTests {
@Autowired
private DSLContext dslContext;
// ...
}
@JooqTest
class MyJooqTests(@Autowired val dslContext: DSLContext) {
// ...
}
JOOQ tests are transactional and roll back at the end of each test by default. If that is not what you want, you can disable transaction management for a test or for the whole test class as shown in the JDBC example.
Auto-configured Data MongoDB Tests
You can use @DataMongoTest
to test MongoDB applications.
By default, it configures a MongoTemplate
, scans for @Document
classes, and configures Spring Data MongoDB repositories.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @DataMongoTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
(For more about using MongoDB with Spring Boot, see "MongoDB".)
A list of the auto-configuration settings that are enabled by @DataMongoTest can be found in the appendix.
|
The following class shows the @DataMongoTest
annotation in use:
@DataMongoTest
class MyDataMongoDbTests {
@Autowired
private MongoTemplate mongoTemplate;
// ...
}
@DataMongoTest
class MyDataMongoDbTests(@Autowired val mongoTemplate: MongoTemplate) {
// ...
}
Auto-configured Data Neo4j Tests
You can use @DataNeo4jTest
to test Neo4j applications.
By default, it scans for @Node
classes, and configures Spring Data Neo4j repositories.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @DataNeo4jTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
(For more about using Neo4J with Spring Boot, see "Neo4j".)
A list of the auto-configuration settings that are enabled by @DataNeo4jTest can be found in the appendix.
|
The following example shows a typical setup for using Neo4J tests in Spring Boot:
@DataNeo4jTest
class MyDataNeo4jTests {
@Autowired
private SomeRepository repository;
// ...
}
@DataNeo4jTest
class MyDataNeo4jTests(@Autowired val repository: SomeRepository) {
// ...
}
By default, Data Neo4j tests are transactional and roll back at the end of each test. See the relevant section in the Spring Framework Reference Documentation for more details. If that is not what you want, you can disable transaction management for a test or for the whole class, as follows:
@DataNeo4jTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class MyDataNeo4jTests {
}
@DataNeo4jTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class MyDataNeo4jTests
Transactional tests are not supported with reactive access.
If you are using this style, you must configure @DataNeo4jTest tests as described above.
|
Auto-configured Data Redis Tests
You can use @DataRedisTest
to test Redis applications.
By default, it scans for @RedisHash
classes and configures Spring Data Redis repositories.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @DataRedisTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
(For more about using Redis with Spring Boot, see "Redis".)
A list of the auto-configuration settings that are enabled by @DataRedisTest can be found in the appendix.
|
The following example shows the @DataRedisTest
annotation in use:
@DataRedisTest
class MyDataRedisTests {
@Autowired
private SomeRepository repository;
// ...
}
@DataRedisTest
class MyDataRedisTests(@Autowired val repository: SomeRepository) {
// ...
}
Auto-configured Data LDAP Tests
You can use @DataLdapTest
to test LDAP applications.
By default, it configures an in-memory embedded LDAP (if available), configures an LdapTemplate
, scans for @Entry
classes, and configures Spring Data LDAP repositories.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @DataLdapTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
(For more about using LDAP with Spring Boot, see "LDAP".)
A list of the auto-configuration settings that are enabled by @DataLdapTest can be found in the appendix.
|
The following example shows the @DataLdapTest
annotation in use:
@DataLdapTest
class MyDataLdapTests {
@Autowired
private LdapTemplate ldapTemplate;
// ...
}
@DataLdapTest
class MyDataLdapTests(@Autowired val ldapTemplate: LdapTemplate) {
// ...
}
In-memory embedded LDAP generally works well for tests, since it is fast and does not require any developer installation. If, however, you prefer to run tests against a real LDAP server, you should exclude the embedded LDAP auto-configuration, as shown in the following example:
@DataLdapTest(excludeAutoConfiguration = EmbeddedLdapAutoConfiguration.class)
class MyDataLdapTests {
// ...
}
@DataLdapTest(excludeAutoConfiguration = [EmbeddedLdapAutoConfiguration::class])
class MyDataLdapTests {
// ...
}
Auto-configured REST Clients
You can use the @RestClientTest
annotation to test REST clients.
By default, it auto-configures Jackson, GSON, and Jsonb support, configures a RestTemplateBuilder
and a RestClient.Builder
, and adds support for MockRestServiceServer
.
Regular @Component
and @ConfigurationProperties
beans are not scanned when the @RestClientTest
annotation is used.
@EnableConfigurationProperties
can be used to include @ConfigurationProperties
beans.
A list of the auto-configuration settings that are enabled by @RestClientTest can be found in the appendix.
|
The specific beans that you want to test should be specified by using the value
or components
attribute of @RestClientTest
.
When using a RestTemplateBuilder
in the beans under test and RestTemplateBuilder.rootUri(String rootUri)
has been called when building the RestTemplate
, then the root URI should be omitted from the MockRestServiceServer
expectations as shown in the following example:
@RestClientTest(RemoteVehicleDetailsService.class)
class MyRestTemplateServiceTests {
@Autowired
private RemoteVehicleDetailsService service;
@Autowired
private MockRestServiceServer server;
@Test
void getVehicleDetailsWhenResultIsSuccessShouldReturnDetails() {
this.server.expect(requestTo("/greet/details")).andRespond(withSuccess("hello", MediaType.TEXT_PLAIN));
String greeting = this.service.callRestService();
assertThat(greeting).isEqualTo("hello");
}
}
@RestClientTest(RemoteVehicleDetailsService::class)
class MyRestTemplateServiceTests(
@Autowired val service: RemoteVehicleDetailsService,
@Autowired val server: MockRestServiceServer) {
@Test
fun getVehicleDetailsWhenResultIsSuccessShouldReturnDetails(): Unit {
server.expect(MockRestRequestMatchers.requestTo("/greet/details"))
.andRespond(MockRestResponseCreators.withSuccess("hello", MediaType.TEXT_PLAIN))
val greeting = service.callRestService()
assertThat(greeting).isEqualTo("hello")
}
}
When using a RestClient.Builder
in the beans under test, or when using a RestTemplateBuilder
without calling rootUri(String rootURI)
, the full URI must be used in the MockRestServiceServer
expectations as shown in the following example:
@RestClientTest(RemoteVehicleDetailsService.class)
class MyRestClientServiceTests {
@Autowired
private RemoteVehicleDetailsService service;
@Autowired
private MockRestServiceServer server;
@Test
void getVehicleDetailsWhenResultIsSuccessShouldReturnDetails() {
this.server.expect(requestTo("https://example.com/greet/details"))
.andRespond(withSuccess("hello", MediaType.TEXT_PLAIN));
String greeting = this.service.callRestService();
assertThat(greeting).isEqualTo("hello");
}
}
@RestClientTest(RemoteVehicleDetailsService::class)
class MyRestClientServiceTests(
@Autowired val service: RemoteVehicleDetailsService,
@Autowired val server: MockRestServiceServer) {
@Test
fun getVehicleDetailsWhenResultIsSuccessShouldReturnDetails(): Unit {
server.expect(MockRestRequestMatchers.requestTo("https://example.com/greet/details"))
.andRespond(MockRestResponseCreators.withSuccess("hello", MediaType.TEXT_PLAIN))
val greeting = service.callRestService()
assertThat(greeting).isEqualTo("hello")
}
}
Auto-configured Spring REST Docs Tests
You can use the @AutoConfigureRestDocs
annotation to use Spring REST Docs in your tests with Mock MVC, REST Assured, or WebTestClient.
It removes the need for the JUnit extension in Spring REST Docs.
@AutoConfigureRestDocs
can be used to override the default output directory (target/generated-snippets
if you are using Maven or build/generated-snippets
if you are using Gradle).
It can also be used to configure the host, scheme, and port that appears in any documented URIs.
Auto-configured Spring REST Docs Tests With Mock MVC
@AutoConfigureRestDocs
customizes the MockMvc
bean to use Spring REST Docs when testing servlet-based web applications.
You can inject it by using @Autowired
and use it in your tests as you normally would when using Mock MVC and Spring REST Docs, as shown in the following example:
@WebMvcTest(UserController.class)
@AutoConfigureRestDocs
class MyUserDocumentationTests {
@Autowired
private MockMvc mvc;
@Test
void listUsers() throws Exception {
this.mvc.perform(get("/users").accept(MediaType.TEXT_PLAIN))
.andExpect(status().isOk())
.andDo(document("list-users"));
}
}
@WebMvcTest(UserController::class)
@AutoConfigureRestDocs
class MyUserDocumentationTests(@Autowired val mvc: MockMvc) {
@Test
fun listUsers() {
mvc.perform(MockMvcRequestBuilders.get("/users").accept(MediaType.TEXT_PLAIN))
.andExpect(MockMvcResultMatchers.status().isOk)
.andDo(MockMvcRestDocumentation.document("list-users"))
}
}
If you require more control over Spring REST Docs configuration than offered by the attributes of @AutoConfigureRestDocs
, you can use a RestDocsMockMvcConfigurationCustomizer
bean, as shown in the following example:
@TestConfiguration(proxyBeanMethods = false)
public class MyRestDocsConfiguration implements RestDocsMockMvcConfigurationCustomizer {
@Override
public void customize(MockMvcRestDocumentationConfigurer configurer) {
configurer.snippets().withTemplateFormat(TemplateFormats.markdown());
}
}
@TestConfiguration(proxyBeanMethods = false)
class MyRestDocsConfiguration : RestDocsMockMvcConfigurationCustomizer {
override fun customize(configurer: MockMvcRestDocumentationConfigurer) {
configurer.snippets().withTemplateFormat(TemplateFormats.markdown())
}
}
If you want to make use of Spring REST Docs support for a parameterized output directory, you can create a RestDocumentationResultHandler
bean.
The auto-configuration calls alwaysDo
with this result handler, thereby causing each MockMvc
call to automatically generate the default snippets.
The following example shows a RestDocumentationResultHandler
being defined:
@TestConfiguration(proxyBeanMethods = false)
public class MyResultHandlerConfiguration {
@Bean
public RestDocumentationResultHandler restDocumentation() {
return MockMvcRestDocumentation.document("{method-name}");
}
}
@TestConfiguration(proxyBeanMethods = false)
class MyResultHandlerConfiguration {
@Bean
fun restDocumentation(): RestDocumentationResultHandler {
return MockMvcRestDocumentation.document("{method-name}")
}
}
Auto-configured Spring REST Docs Tests With WebTestClient
@AutoConfigureRestDocs
can also be used with WebTestClient
when testing reactive web applications.
You can inject it by using @Autowired
and use it in your tests as you normally would when using @WebFluxTest
and Spring REST Docs, as shown in the following example:
@WebFluxTest
@AutoConfigureRestDocs
class MyUsersDocumentationTests {
@Autowired
private WebTestClient webTestClient;
@Test
void listUsers() {
this.webTestClient
.get().uri("/")
.exchange()
.expectStatus()
.isOk()
.expectBody()
.consumeWith(document("list-users"));
}
}
@WebFluxTest
@AutoConfigureRestDocs
class MyUsersDocumentationTests(@Autowired val webTestClient: WebTestClient) {
@Test
fun listUsers() {
webTestClient
.get().uri("/")
.exchange()
.expectStatus()
.isOk
.expectBody()
.consumeWith(WebTestClientRestDocumentation.document("list-users"))
}
}
If you require more control over Spring REST Docs configuration than offered by the attributes of @AutoConfigureRestDocs
, you can use a RestDocsWebTestClientConfigurationCustomizer
bean, as shown in the following example:
@TestConfiguration(proxyBeanMethods = false)
public class MyRestDocsConfiguration implements RestDocsWebTestClientConfigurationCustomizer {
@Override
public void customize(WebTestClientRestDocumentationConfigurer configurer) {
configurer.snippets().withEncoding("UTF-8");
}
}
@TestConfiguration(proxyBeanMethods = false)
class MyRestDocsConfiguration : RestDocsWebTestClientConfigurationCustomizer {
override fun customize(configurer: WebTestClientRestDocumentationConfigurer) {
configurer.snippets().withEncoding("UTF-8")
}
}
If you want to make use of Spring REST Docs support for a parameterized output directory, you can use a WebTestClientBuilderCustomizer
to configure a consumer for every entity exchange result.
The following example shows such a WebTestClientBuilderCustomizer
being defined:
@TestConfiguration(proxyBeanMethods = false)
public class MyWebTestClientBuilderCustomizerConfiguration {
@Bean
public WebTestClientBuilderCustomizer restDocumentation() {
return (builder) -> builder.entityExchangeResultConsumer(document("{method-name}"));
}
}
@TestConfiguration(proxyBeanMethods = false)
class MyWebTestClientBuilderCustomizerConfiguration {
@Bean
fun restDocumentation(): WebTestClientBuilderCustomizer {
return WebTestClientBuilderCustomizer { builder: WebTestClient.Builder ->
builder.entityExchangeResultConsumer(
WebTestClientRestDocumentation.document("{method-name}")
)
}
}
}
Auto-configured Spring REST Docs Tests With REST Assured
@AutoConfigureRestDocs
makes a RequestSpecification
bean, preconfigured to use Spring REST Docs, available to your tests.
You can inject it by using @Autowired
and use it in your tests as you normally would when using REST Assured and Spring REST Docs, as shown in the following example:
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
@AutoConfigureRestDocs
class MyUserDocumentationTests {
@Test
void listUsers(@Autowired RequestSpecification documentationSpec, @LocalServerPort int port) {
given(documentationSpec)
.filter(document("list-users"))
.when()
.port(port)
.get("/")
.then().assertThat()
.statusCode(is(200));
}
}
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
@AutoConfigureRestDocs
class MyUserDocumentationTests {
@Test
fun listUsers(@Autowired documentationSpec: RequestSpecification?, @LocalServerPort port: Int) {
RestAssured.given(documentationSpec)
.filter(RestAssuredRestDocumentation.document("list-users"))
.`when`()
.port(port)["/"]
.then().assertThat()
.statusCode(Matchers.`is`(200))
}
}
If you require more control over Spring REST Docs configuration than offered by the attributes of @AutoConfigureRestDocs
, a RestDocsRestAssuredConfigurationCustomizer
bean can be used, as shown in the following example:
@TestConfiguration(proxyBeanMethods = false)
public class MyRestDocsConfiguration implements RestDocsRestAssuredConfigurationCustomizer {
@Override
public void customize(RestAssuredRestDocumentationConfigurer configurer) {
configurer.snippets().withTemplateFormat(TemplateFormats.markdown());
}
}
@TestConfiguration(proxyBeanMethods = false)
class MyRestDocsConfiguration : RestDocsRestAssuredConfigurationCustomizer {
override fun customize(configurer: RestAssuredRestDocumentationConfigurer) {
configurer.snippets().withTemplateFormat(TemplateFormats.markdown())
}
}
Auto-configured Spring Web Services Tests
Auto-configured Spring Web Services Client Tests
You can use @WebServiceClientTest
to test applications that call web services using the Spring Web Services project.
By default, it configures a mock WebServiceServer
bean and automatically customizes your WebServiceTemplateBuilder
.
(For more about using Web Services with Spring Boot, see "Web Services".)
A list of the auto-configuration settings that are enabled by @WebServiceClientTest can be found in the appendix.
|
The following example shows the @WebServiceClientTest
annotation in use:
@WebServiceClientTest(SomeWebService.class)
class MyWebServiceClientTests {
@Autowired
private MockWebServiceServer server;
@Autowired
private SomeWebService someWebService;
@Test
void mockServerCall() {
this.server
.expect(payload(new StringSource("<request/>")))
.andRespond(withPayload(new StringSource("<response><status>200</status></response>")));
assertThat(this.someWebService.test())
.extracting(Response::getStatus)
.isEqualTo(200);
}
}
@WebServiceClientTest(SomeWebService::class)
class MyWebServiceClientTests(@Autowired val server: MockWebServiceServer, @Autowired val someWebService: SomeWebService) {
@Test
fun mockServerCall() {
server
.expect(RequestMatchers.payload(StringSource("<request/>")))
.andRespond(ResponseCreators.withPayload(StringSource("<response><status>200</status></response>")))
assertThat(this.someWebService.test()).extracting(Response::status).isEqualTo(200)
}
}
Auto-configured Spring Web Services Server Tests
You can use @WebServiceServerTest
to test applications that implement web services using the Spring Web Services project.
By default, it configures a MockWebServiceClient
bean that can be used to call your web service endpoints.
(For more about using Web Services with Spring Boot, see "Web Services".)
A list of the auto-configuration settings that are enabled by @WebServiceServerTest can be found in the appendix.
|
The following example shows the @WebServiceServerTest
annotation in use:
@WebServiceServerTest(ExampleEndpoint.class)
class MyWebServiceServerTests {
@Autowired
private MockWebServiceClient client;
@Test
void mockServerCall() {
this.client
.sendRequest(RequestCreators.withPayload(new StringSource("<ExampleRequest/>")))
.andExpect(ResponseMatchers.payload(new StringSource("<ExampleResponse>42</ExampleResponse>")));
}
}
@WebServiceServerTest(ExampleEndpoint::class)
class MyWebServiceServerTests(@Autowired val client: MockWebServiceClient) {
@Test
fun mockServerCall() {
client
.sendRequest(RequestCreators.withPayload(StringSource("<ExampleRequest/>")))
.andExpect(ResponseMatchers.payload(StringSource("<ExampleResponse>42</ExampleResponse>")))
}
}
Additional Auto-configuration and Slicing
Each slice provides one or more @AutoConfigure…
annotations that namely defines the auto-configurations that should be included as part of a slice.
Additional auto-configurations can be added on a test-by-test basis by creating a custom @AutoConfigure…
annotation or by adding @ImportAutoConfiguration
to the test as shown in the following example:
@JdbcTest
@ImportAutoConfiguration(IntegrationAutoConfiguration.class)
class MyJdbcTests {
}
@JdbcTest
@ImportAutoConfiguration(IntegrationAutoConfiguration::class)
class MyJdbcTests
Make sure to not use the regular @Import annotation to import auto-configurations as they are handled in a specific way by Spring Boot.
|
Alternatively, additional auto-configurations can be added for any use of a slice annotation by registering them in a file stored in META-INF/spring
as shown in the following example:
com.example.IntegrationAutoConfiguration
In this example, the com.example.IntegrationAutoConfiguration
is enabled on every test annotated with @JdbcTest
.
You can use comments with # in this file.
|
A slice or @AutoConfigure… annotation can be customized this way as long as it is meta-annotated with @ImportAutoConfiguration .
|
User Configuration and Slicing
If you structure your code in a sensible way, your @SpringBootApplication
class is used by default as the configuration of your tests.
It then becomes important not to litter the application’s main class with configuration settings that are specific to a particular area of its functionality.
Assume that you are using Spring Data MongoDB, you rely on the auto-configuration for it, and you have enabled auditing.
You could define your @SpringBootApplication
as follows:
@SpringBootApplication
@EnableMongoAuditing
public class MyApplication {
// ...
}
@SpringBootApplication
@EnableMongoAuditing
class MyApplication {
// ...
}
Because this class is the source configuration for the test, any slice test actually tries to enable Mongo auditing, which is definitely not what you want to do.
A recommended approach is to move that area-specific configuration to a separate @Configuration
class at the same level as your application, as shown in the following example:
@Configuration(proxyBeanMethods = false)
@EnableMongoAuditing
public class MyMongoConfiguration {
// ...
}
@Configuration(proxyBeanMethods = false)
@EnableMongoAuditing
class MyMongoConfiguration {
// ...
}
Depending on the complexity of your application, you may either have a single @Configuration class for your customizations or one class per domain area.
The latter approach lets you enable it in one of your tests, if necessary, with the @Import annotation.
See this how-to section for more details on when you might want to enable specific @Configuration classes for slice tests.
|
Test slices exclude @Configuration
classes from scanning.
For example, for a @WebMvcTest
, the following configuration will not include the given WebMvcConfigurer
bean in the application context loaded by the test slice:
@Configuration(proxyBeanMethods = false)
public class MyWebConfiguration {
@Bean
public WebMvcConfigurer testConfigurer() {
return new WebMvcConfigurer() {
// ...
};
}
}
@Configuration(proxyBeanMethods = false)
class MyWebConfiguration {
@Bean
fun testConfigurer(): WebMvcConfigurer {
return object : WebMvcConfigurer {
// ...
}
}
}
The configuration below will, however, cause the custom WebMvcConfigurer
to be loaded by the test slice.
@Component
public class MyWebMvcConfigurer implements WebMvcConfigurer {
// ...
}
@Component
class MyWebMvcConfigurer : WebMvcConfigurer {
// ...
}
Another source of confusion is classpath scanning. Assume that, while you structured your code in a sensible way, you need to scan an additional package. Your application may resemble the following code:
@SpringBootApplication
@ComponentScan({ "com.example.app", "com.example.another" })
public class MyApplication {
// ...
}
@SpringBootApplication
@ComponentScan("com.example.app", "com.example.another")
class MyApplication {
// ...
}
Doing so effectively overrides the default component scan directive with the side effect of scanning those two packages regardless of the slice that you chose.
For instance, a @DataJpaTest
seems to suddenly scan components and user configurations of your application.
Again, moving the custom directive to a separate class is a good way to fix this issue.
If this is not an option for you, you can create a @SpringBootConfiguration somewhere in the hierarchy of your test so that it is used instead.
Alternatively, you can specify a source for your test, which disables the behavior of finding a default one.
|
Using Spock to Test Spring Boot Applications
Spock 2.2 or later can be used to test a Spring Boot application.
To do so, add a dependency on a -groovy-4.0
version of Spock’s spock-spring
module to your application’s build.
spock-spring
integrates Spring’s test framework into Spock.
See the documentation for Spock’s Spring module for further details.
7.9.4. Testcontainers
The Testcontainers library provides a way to manage services running inside Docker containers. It integrates with JUnit, allowing you to write a test class that can start up a container before any of the tests run. Testcontainers is especially useful for writing integration tests that talk to a real backend service such as MySQL, MongoDB, Cassandra and others.
Testcontainers can be used in a Spring Boot test as follows:
@Testcontainers
@SpringBootTest
class MyIntegrationTests {
@Container
static Neo4jContainer<?> neo4j = new Neo4jContainer<>("neo4j:5");
@Test
void myTest() {
// ...
}
}
@Testcontainers
@SpringBootTest
class MyIntegrationTests {
@Test
fun myTest() {
// ...
}
companion object {
@Container
val neo4j = Neo4jContainer("neo4j:5")
}
}
This will start up a docker container running Neo4j (if Docker is running locally) before any of the tests are run. In most cases, you will need to configure the application to connect to the service running in the container.
Service Connections
A service connection is a connection to any remote service. Spring Boot’s auto-configuration can consume the details of a service connection and use them to establish a connection to a remote service. When doing so, the connection details take precedence over any connection-related configuration properties.
When using Testcontainers, connection details can be automatically created for a service running in a container by annotating the container field in the test class.
@Testcontainers
@SpringBootTest
class MyIntegrationTests {
@Container
@ServiceConnection
static Neo4jContainer<?> neo4j = new Neo4jContainer<>("neo4j:5");
@Test
void myTest() {
// ...
}
}
@Testcontainers
@SpringBootTest
class MyIntegrationTests {
@Test
fun myTest() {
// ...
}
companion object {
@Container
@ServiceConnection
val neo4j = Neo4jContainer("neo4j:5")
}
}
Thanks to @ServiceConnection
, the above configuration allows Neo4j-related beans in the application to communicate with Neo4j running inside the Testcontainers-managed Docker container.
This is done by automatically defining a Neo4jConnectionDetails
bean which is then used by the Neo4j auto-configuration, overriding any connection-related configuration properties.
You’ll need to add the spring-boot-testcontainers module as a test dependency in order to use service connections with Testcontainers.
|
Service connection annotations are processed by ContainerConnectionDetailsFactory
classes registered with spring.factories
.
A ContainerConnectionDetailsFactory
can create a ConnectionDetails
bean based on a specific Container
subclass, or the Docker image name.
The following service connection factories are provided in the spring-boot-testcontainers
jar:
Connection Details | Matched on |
---|---|
|
Containers named "symptoma/activemq" |
|
Containers of type |
|
Containers of type |
|
Containers of type |
|
Containers of type |
|
Containers of type |
|
Containers of type |
|
Containers of type |
|
Containers of type |
|
Containers of type |
|
Containers named "otel/opentelemetry-collector-contrib" |
|
Containers named "otel/opentelemetry-collector-contrib" |
|
Containers of type |
|
Containers of type |
|
Containers of type |
|
Containers named "redis" |
|
Containers named "openzipkin/zipkin" |
By default all applicable connection details beans will be created for a given If you want to create only a subset of the applicable types, you can use the |
By default Container.getDockerImageName()
is used to obtain the name used to find connection details.
This works as long as Spring Boot is able to get the instance of the Container
, which is the case when using a static
field like in the example above.
If you’re using a @Bean
method, Spring Boot won’t call the bean method to get the Docker image name, because this would cause eager initialization issues.
Instead, the return type of the bean method is used to find out which connection detail should be used.
This works as long as you’re using typed containers, e.g. Neo4jContainer
or RabbitMQContainer
.
This stops working if you’re using GenericContainer
, e.g. with Redis, as shown in the following example:
@TestConfiguration(proxyBeanMethods = false)
public class MyRedisConfiguration {
@Bean
@ServiceConnection(name = "redis")
public GenericContainer<?> redisContainer() {
return new GenericContainer<>("redis:7");
}
}
@TestConfiguration(proxyBeanMethods = false)
class MyRedisConfiguration {
@Bean
@ServiceConnection(name = "redis")
fun redisContainer(): GenericContainer<*> {
return GenericContainer("redis:7")
}
}
Spring Boot can’t tell from GenericContainer
which container image is used, so the name
attribute from @ServiceConnection
must be used to provide that hint.
You can also can use the name
attribute of @ServiceConnection
to override which connection detail will be used, for example when using custom images.
If you are using the Docker image registry.mycompany.com/mirror/myredis
, you’d use @ServiceConnection(name="redis")
to ensure RedisConnectionDetails
are created.
Dynamic Properties
A slightly more verbose but also more flexible alternative to service connections is @DynamicPropertySource
.
A static @DynamicPropertySource
method allows adding dynamic property values to the Spring Environment.
@Testcontainers
@SpringBootTest
class MyIntegrationTests {
@Container
static Neo4jContainer<?> neo4j = new Neo4jContainer<>("neo4j:5");
@Test
void myTest() {
// ...
}
@DynamicPropertySource
static void neo4jProperties(DynamicPropertyRegistry registry) {
registry.add("spring.neo4j.uri", neo4j::getBoltUrl);
}
}
@Testcontainers
@SpringBootTest
class MyIntegrationTests {
@Test
fun myTest() {
// ...
}
companion object {
@Container
val neo4j = Neo4jContainer("neo4j:5")
@DynamicPropertySource
fun neo4jProperties(registry: DynamicPropertyRegistry) {
registry.add("spring.neo4j.uri") { neo4j.boltUrl }
}
}
}
The above configuration allows Neo4j-related beans in the application to communicate with Neo4j running inside the Testcontainers-managed Docker container.
7.9.5. Test Utilities
A few test utility classes that are generally useful when testing your application are packaged as part of spring-boot
.
ConfigDataApplicationContextInitializer
ConfigDataApplicationContextInitializer
is an ApplicationContextInitializer
that you can apply to your tests to load Spring Boot application.properties
files.
You can use it when you do not need the full set of features provided by @SpringBootTest
, as shown in the following example:
@ContextConfiguration(classes = Config.class, initializers = ConfigDataApplicationContextInitializer.class)
class MyConfigFileTests {
// ...
}
@ContextConfiguration(classes = [Config::class], initializers = [ConfigDataApplicationContextInitializer::class])
class MyConfigFileTests {
// ...
}
Using ConfigDataApplicationContextInitializer alone does not provide support for @Value("${…}") injection.
Its only job is to ensure that application.properties files are loaded into Spring’s Environment .
For @Value support, you need to either additionally configure a PropertySourcesPlaceholderConfigurer or use @SpringBootTest , which auto-configures one for you.
|
TestPropertyValues
TestPropertyValues
lets you quickly add properties to a ConfigurableEnvironment
or ConfigurableApplicationContext
.
You can call it with key=value
strings, as follows:
class MyEnvironmentTests {
@Test
void testPropertySources() {
MockEnvironment environment = new MockEnvironment();
TestPropertyValues.of("org=Spring", "name=Boot").applyTo(environment);
assertThat(environment.getProperty("name")).isEqualTo("Boot");
}
}
class MyEnvironmentTests {
@Test
fun testPropertySources() {
val environment = MockEnvironment()
TestPropertyValues.of("org=Spring", "name=Boot").applyTo(environment)
assertThat(environment.getProperty("name")).isEqualTo("Boot")
}
}
OutputCapture
OutputCapture
is a JUnit Extension
that you can use to capture System.out
and System.err
output.
To use it, add @ExtendWith(OutputCaptureExtension.class)
and inject CapturedOutput
as an argument to your test class constructor or test method as follows:
@ExtendWith(OutputCaptureExtension.class)
class MyOutputCaptureTests {
@Test
void testName(CapturedOutput output) {
System.out.println("Hello World!");
assertThat(output).contains("World");
}
}
@ExtendWith(OutputCaptureExtension::class)
class MyOutputCaptureTests {
@Test
fun testName(output: CapturedOutput?) {
println("Hello World!")
assertThat(output).contains("World")
}
}
TestRestTemplate
TestRestTemplate
is a convenience alternative to Spring’s RestTemplate
that is useful in integration tests.
You can get a vanilla template or one that sends Basic HTTP authentication (with a username and password).
In either case, the template is fault tolerant.
This means that it behaves in a test-friendly way by not throwing exceptions on 4xx and 5xx errors.
Instead, such errors can be detected through the returned ResponseEntity
and its status code.
Spring Framework 5.0 provides a new WebTestClient that works for WebFlux integration tests and both WebFlux and MVC end-to-end testing.
It provides a fluent API for assertions, unlike TestRestTemplate .
|
It is recommended, but not mandatory, to use the Apache HTTP Client (version 5.1 or better).
If you have that on your classpath, the TestRestTemplate
responds by configuring the client appropriately.
If you do use Apache’s HTTP client, some additional test-friendly features are enabled:
-
Redirects are not followed (so you can assert the response location).
-
Cookies are ignored (so the template is stateless).
TestRestTemplate
can be instantiated directly in your integration tests, as shown in the following example:
class MyTests {
private final TestRestTemplate template = new TestRestTemplate();
@Test
void testRequest() {
ResponseEntity<String> headers = this.template.getForEntity("https://myhost.example.com/example", String.class);
assertThat(headers.getHeaders().getLocation()).hasHost("other.example.com");
}
}
class MyTests {
private val template = TestRestTemplate()
@Test
fun testRequest() {
val headers = template.getForEntity("https://myhost.example.com/example", String::class.java)
assertThat(headers.headers.location).hasHost("other.example.com")
}
}
Alternatively, if you use the @SpringBootTest
annotation with WebEnvironment.RANDOM_PORT
or WebEnvironment.DEFINED_PORT
, you can inject a fully configured TestRestTemplate
and start using it.
If necessary, additional customizations can be applied through the RestTemplateBuilder
bean.
Any URLs that do not specify a host and port automatically connect to the embedded server, as shown in the following example:
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class MySpringBootTests {
@Autowired
private TestRestTemplate template;
@Test
void testRequest() {
HttpHeaders headers = this.template.getForEntity("/example", String.class).getHeaders();
assertThat(headers.getLocation()).hasHost("other.example.com");
}
@TestConfiguration(proxyBeanMethods = false)
static class RestTemplateBuilderConfiguration {
@Bean
RestTemplateBuilder restTemplateBuilder() {
return new RestTemplateBuilder().setConnectTimeout(Duration.ofSeconds(1))
.setReadTimeout(Duration.ofSeconds(1));
}
}
}
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class MySpringBootTests(@Autowired val template: TestRestTemplate) {
@Test
fun testRequest() {
val headers = template.getForEntity("/example", String::class.java).headers
assertThat(headers.location).hasHost("other.example.com")
}
@TestConfiguration(proxyBeanMethods = false)
internal class RestTemplateBuilderConfiguration {
@Bean
fun restTemplateBuilder(): RestTemplateBuilder {
return RestTemplateBuilder().setConnectTimeout(Duration.ofSeconds(1))
.setReadTimeout(Duration.ofSeconds(1))
}
}
}
7.10. Docker Compose Support
Docker Compose is a popular technology that can be used to define and manage multiple containers for services that your application needs.
A compose.yml
file is typically created next to your application which defines and configures service containers.
A typical workflow with Docker Compose is to run docker compose up
, work on your application with it connecting to started services, then run docker compose down
when you are finished.
The spring-boot-docker-compose
module can be included in a project to provide support for working with containers using Docker Compose.
Add the module dependency to your build, as shown in the following listings for Maven and Gradle:
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-docker-compose</artifactId>
<optional>true</optional>
</dependency>
</dependencies>
dependencies {
developmentOnly("org.springframework.boot:spring-boot-docker-compose")
}
The docker compose or docker-compose CLI application needs to be on your path in order for Spring Boot’s support to work correctly.
|
When this module is included as a dependency Spring Boot will do the following:
-
Search for a
compose.yml
and other common compose filenames in your application directory -
Call
docker compose up
with the discoveredcompose.yml
-
Create service connection beans for each supported container
-
Call
docker compose stop
when the application is shutdown
If the Docker Compose services are already running when starting the application, Spring Boot will only create the service connection beans for each supported container.
It will not call docker compose up
again and it will not call docker compose stop
when the application is shutdown.
By default, Spring Boot’s Docker Compose support is disabled when running tests.
To enable it, set spring.docker.compose.skip.in-tests to false .
|
7.10.1. Service Connections
A service connection is a connection to any remote service. Spring Boot’s auto-configuration can consume the details of a service connection and use them to establish a connection to a remote service. When doing so, the connection details take precedence over any connection-related configuration properties.
When using Spring Boot’s Docker Compose support, service connections are established to the port mapped by the container.
Docker compose is usually used in such a way that the ports inside the container are mapped to ephemeral ports on your computer. For example, a Postgres server may run inside the container using port 5432 but be mapped to a totally different port locally. The service connection will always discover and use the locally mapped port. |
Service connections are established by using the image name of the container. The following service connections are currently supported:
Connection Details | Matched on |
---|---|
|
Containers named "symptoma/activemq" |
|
Containers named "cassandra" |
|
Containers named "elasticsearch" |
|
Containers named "gvenzl/oracle-free", "gvenzl/oracle-xe", "mariadb", "mssql/server", "mysql", or "postgres" |
|
Containers named "mongo" |
|
Containers named "neo4j" |
|
Containers named "otel/opentelemetry-collector-contrib" |
|
Containers named "otel/opentelemetry-collector-contrib" |
|
Containers named "apachepulsar/pulsar" |
|
Containers named "gvenzl/oracle-free", "gvenzl/oracle-xe", "mariadb", "mssql/server", "mysql", or "postgres" |
|
Containers named "rabbitmq" |
|
Containers named "redis" |
|
Containers named "openzipkin/zipkin". |
7.10.2. Custom Images
Sometimes you may need to use your own version of an image to provide a service. You can use any custom image as long as it behaves in the same way as the standard image. Specifically, any environment variables that the standard image supports must also be used in your custom image.
If your image uses a different name, you can use a label in your compose.yml
file so that Spring Boot can provide a service connection.
Use a label named org.springframework.boot.service-connection
to provide the service name.
For example:
services:
redis:
image: 'mycompany/mycustomredis:7.0'
ports:
- '6379'
labels:
org.springframework.boot.service-connection: redis
7.10.3. Skipping Specific Containers
If you have a container image defined in your compose.yml
that you don’t want connected to your application you can use a label to ignore it.
Any container with labeled with org.springframework.boot.ignore
will be ignored by Spring Boot.
For example:
services:
redis:
image: 'redis:7.0'
ports:
- '6379'
labels:
org.springframework.boot.ignore: true
7.10.4. Using a Specific Compose File
If your compose file is not in the same directory as your application, or if it’s named differently, you can use spring.docker.compose.file
in your application.properties
or application.yaml
to point to a different file.
Properties can be defined as an exact path or a path that’s relative to your application.
For example:
spring.docker.compose.file=../my-compose.yml
spring:
docker:
compose:
file: "../my-compose.yml"
7.10.5. Waiting for Container Readiness
Containers started by Docker Compose may take some time to become fully ready.
The recommended way of checking for readiness is to add a healthcheck
section under the service definition in your compose.yml
file.
Since it’s not uncommon for healthcheck
configuration to be omitted from compose.yml
files, Spring Boot also checks directly for service readiness.
By default, a container is considered ready when a TCP/IP connection can be established to its mapped port.
You can disable this on a per-container basis by adding a org.springframework.boot.readiness-check.tcp.disable
label in your compose.yml
file.
For example:
services:
redis:
image: 'redis:7.0'
ports:
- '6379'
labels:
org.springframework.boot.readiness-check.tcp.disable: true
You can also change timeout values in your application.properties
or application.yaml
file:
spring.docker.compose.readiness.tcp.connect-timeout=10s
spring.docker.compose.readiness.tcp.read-timeout=5s
spring:
docker:
compose:
readiness:
tcp:
connect-timeout: 10s
read-timeout: 5s
The overall timeout can be configured using spring.docker.compose.readiness.timeout
.
7.10.6. Controlling the Docker Compose Lifecycle
By default Spring Boot calls docker compose up
when your application starts and docker compose stop
when it’s shut down.
If you prefer to have different lifecycle management you can use the spring.docker.compose.lifecycle-management
property.
The following values are supported:
-
none
- Do not start or stop Docker Compose -
start-only
- Start Docker Compose when the application starts and leave it running -
start-and-stop
- Start Docker Compose when the application starts and stop it when the JVM exits
In addition you can use the spring.docker.compose.start.command
property to change whether docker compose up
or docker compose start
is used.
The spring.docker.compose.stop.command
allows you to configure if docker compose down
or docker compose stop
is used.
The following example shows how lifecycle management can be configured:
spring.docker.compose.lifecycle-management=start-and-stop
spring.docker.compose.start.command=start
spring.docker.compose.stop.command=down
spring.docker.compose.stop.timeout=1m
spring:
docker:
compose:
lifecycle-management: start-and-stop
start:
command: start
stop:
command: down
timeout: 1m
7.10.7. Activating Docker Compose Profiles
Docker Compose profiles are similar to Spring profiles in that they let you adjust your Docker Compose configuration for specific environments.
If you want to activate a specific Docker Compose profile you can use the spring.docker.compose.profiles.active
property in your application.properties
or application.yaml
file:
spring.docker.compose.profiles.active=myprofile
spring:
docker:
compose:
profiles:
active: "myprofile"
7.11. Testcontainers Support
As well as using Testcontainers for integration testing, it’s also possible to use them at development time. The next sections will provide more details about that.
7.11.1. Using Testcontainers at Development Time
This approach allows developers to quickly start containers for the services that the application depends on, removing the need to manually provision things like database servers. Using Testcontainers in this way provides functionality similar to Docker Compose, except that your container configuration is in Java rather than YAML.
To use Testcontainers at development time you need to launch your application using your “test” classpath rather than “main”. This will allow you to access all declared test dependencies and give you a natural place to write your test configuration.
To create a test launchable version of your application you should create an “Application” class in the src/test
directory.
For example, if your main application is in src/main/java/com/example/MyApplication.java
, you should create src/test/java/com/example/TestMyApplication.java
The TestMyApplication
class can use the SpringApplication.from(…)
method to launch the real application:
public class TestMyApplication {
public static void main(String[] args) {
SpringApplication.from(MyApplication::main).run(args);
}
}
fun main(args: Array<String>) {
fromApplication<MyApplication>().run(*args)
}
You’ll also need to define the Container
instances that you want to start along with your application.
To do this, you need to make sure that the spring-boot-testcontainers
module has been added as a test
dependency.
Once that has been done, you can create a @TestConfiguration
class that declares @Bean
methods for the containers you want to start.
You can also annotate your @Bean
methods with @ServiceConnection
in order to create ConnectionDetails
beans.
See the service connections section for details of the supported technologies.
A typical Testcontainers configuration would look like this:
@TestConfiguration(proxyBeanMethods = false)
public class MyContainersConfiguration {
@Bean
@ServiceConnection
public Neo4jContainer<?> neo4jContainer() {
return new Neo4jContainer<>("neo4j:5");
}
}
@TestConfiguration(proxyBeanMethods = false)
class MyContainersConfiguration {
@Bean
@ServiceConnection
fun neo4jContainer(): Neo4jContainer<*> {
return Neo4jContainer("neo4j:5")
}
}
The lifecycle of Container beans is automatically managed by Spring Boot.
Containers will be started and stopped automatically.
|
You can use the spring.testcontainers.beans.startup property to change how containers are started.
By default sequential startup is used, but you may also choose parallel if you wish to start multiple containers in parallel.
|
Once you have defined your test configuration, you can use the with(…)
method to attach it to your test launcher:
public class TestMyApplication {
public static void main(String[] args) {
SpringApplication.from(MyApplication::main).with(MyContainersConfiguration.class).run(args);
}
}
fun main(args: Array<String>) {
fromApplication<MyApplication>().with(MyContainersConfiguration::class).run(*args)
}
You can now launch TestMyApplication
as you would any regular Java main
method application to start your application and the containers that it needs to run.
You can use the Maven goal spring-boot:test-run or the Gradle task bootTestRun to do this from the command line.
|
Contributing Dynamic Properties at Development Time
If you want to contribute dynamic properties at development time from your Container
@Bean
methods, you can do so by injecting a DynamicPropertyRegistry
.
This works in a similar way to the @DynamicPropertySource
annotation that you can use in your tests.
It allows you to add properties that will become available once your container has started.
A typical configuration would look like this:
@TestConfiguration(proxyBeanMethods = false)
public class MyContainersConfiguration {
@Bean
public MongoDBContainer mongoDbContainer(DynamicPropertyRegistry properties) {
MongoDBContainer container = new MongoDBContainer("mongo:5.0");
properties.add("spring.data.mongodb.host", container::getHost);
properties.add("spring.data.mongodb.port", container::getFirstMappedPort);
return container;
}
}
@TestConfiguration(proxyBeanMethods = false)
class MyContainersConfiguration {
@Bean
fun monogDbContainer(properties: DynamicPropertyRegistry): MongoDBContainer {
var container = MongoDBContainer("mongo:5.0")
properties.add("spring.data.mongodb.host", container::getHost);
properties.add("spring.data.mongodb.port", container::getFirstMappedPort);
return container
}
}
Using a @ServiceConnection is recommended whenever possible, however, dynamic properties can be a useful fallback for technologies that don’t yet have @ServiceConnection support.
|
Importing Testcontainer Declaration Classes
A common pattern when using Testcontainers is to declare Container
instances as static fields.
Often these fields are defined directly on the test class.
They can also be declared on a parent class or on an interface that the test implements.
For example, the following MyContainers
interface declares mongo
and neo4j
containers:
public interface MyContainers {
@Container
@ServiceConnection
MongoDBContainer mongoContainer = new MongoDBContainer("mongo:5.0");
@Container
@ServiceConnection
Neo4jContainer<?> neo4jContainer = new Neo4jContainer<>("neo4j:5");
}
If you already have containers defined in this way, or you just prefer this style, you can import these declaration classes rather than defining you containers as @Bean
methods.
To do so, add the @ImportTestcontainers
annotation to your test configuration class:
@TestConfiguration(proxyBeanMethods = false)
@ImportTestcontainers(MyContainers.class)
public class MyContainersConfiguration {
}
@TestConfiguration(proxyBeanMethods = false)
@ImportTestcontainers(MyContainers::class)
class MyContainersConfiguration {
}
If you don’t intend to use the service connections feature but want to use @DynamicPropertySource instead, remove the @ServiceConnection annotation from the Container fields.
You can also add @DynamicPropertySource annotated methods to your declaration class.
|
Using DevTools with Testcontainers at Development Time
When using devtools, you can annotate beans and bean methods with @RestartScope
.
Such beans won’t be recreated when the devtools restart the application.
This is especially useful for Testcontainer Container
beans, as they keep their state despite the application restart.
@TestConfiguration(proxyBeanMethods = false)
public class MyContainersConfiguration {
@Bean
@RestartScope
@ServiceConnection
public MongoDBContainer mongoDbContainer() {
return new MongoDBContainer("mongo:5.0");
}
}
@TestConfiguration(proxyBeanMethods = false)
class MyContainersConfiguration {
@Bean
@RestartScope
@ServiceConnection
fun monogDbContainer(): MongoDBContainer {
return MongoDBContainer("mongo:5.0")
}
}
If you’re using Gradle and want to use this feature, you need to change the configuration of the spring-boot-devtools dependency from developmentOnly to testImplementation .
With the default scope of developmentOnly , the bootTestRun task will not pick up changes in your code, as the devtools are not active.
|
7.12. Creating Your Own Auto-configuration
If you work in a company that develops shared libraries, or if you work on an open-source or commercial library, you might want to develop your own auto-configuration. Auto-configuration classes can be bundled in external jars and still be picked up by Spring Boot.
Auto-configuration can be associated to a “starter” that provides the auto-configuration code as well as the typical libraries that you would use with it. We first cover what you need to know to build your own auto-configuration and then we move on to the typical steps required to create a custom starter.
7.12.1. Understanding Auto-configured Beans
Classes that implement auto-configuration are annotated with @AutoConfiguration
.
This annotation itself is meta-annotated with @Configuration
, making auto-configurations standard @Configuration
classes.
Additional @Conditional
annotations are used to constrain when the auto-configuration should apply.
Usually, auto-configuration classes use @ConditionalOnClass
and @ConditionalOnMissingBean
annotations.
This ensures that auto-configuration applies only when relevant classes are found and when you have not declared your own @Configuration
.
You can browse the source code of spring-boot-autoconfigure
to see the @AutoConfiguration
classes that Spring provides (see the META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports
file).
7.12.2. Locating Auto-configuration Candidates
Spring Boot checks for the presence of a META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports
file within your published jar.
The file should list your configuration classes, with one class name per line, as shown in the following example:
com.mycorp.libx.autoconfigure.LibXAutoConfiguration com.mycorp.libx.autoconfigure.LibXWebAutoConfiguration
You can add comments to the imports file using the # character.
|
Auto-configurations must be loaded only by being named in the imports file.
Make sure that they are defined in a specific package space and that they are never the target of component scanning.
Furthermore, auto-configuration classes should not enable component scanning to find additional components.
Specific @Import annotations should be used instead.
|
If your configuration needs to be applied in a specific order, you can use the before
, beforeName
, after
and afterName
attributes on the @AutoConfiguration
annotation or the dedicated @AutoConfigureBefore
and @AutoConfigureAfter
annotations.
For example, if you provide web-specific configuration, your class may need to be applied after WebMvcAutoConfiguration
.
If you want to order certain auto-configurations that should not have any direct knowledge of each other, you can also use @AutoConfigureOrder
.
That annotation has the same semantic as the regular @Order
annotation but provides a dedicated order for auto-configuration classes.
As with standard @Configuration
classes, the order in which auto-configuration classes are applied only affects the order in which their beans are defined.
The order in which those beans are subsequently created is unaffected and is determined by each bean’s dependencies and any @DependsOn
relationships.
7.12.3. Condition Annotations
You almost always want to include one or more @Conditional
annotations on your auto-configuration class.
The @ConditionalOnMissingBean
annotation is one common example that is used to allow developers to override auto-configuration if they are not happy with your defaults.
Spring Boot includes a number of @Conditional
annotations that you can reuse in your own code by annotating @Configuration
classes or individual @Bean
methods.
These annotations include:
Class Conditions
The @ConditionalOnClass
and @ConditionalOnMissingClass
annotations let @Configuration
classes be included based on the presence or absence of specific classes.
Due to the fact that annotation metadata is parsed by using ASM, you can use the value
attribute to refer to the real class, even though that class might not actually appear on the running application classpath.
You can also use the name
attribute if you prefer to specify the class name by using a String
value.
This mechanism does not apply the same way to @Bean
methods where typically the return type is the target of the condition: before the condition on the method applies, the JVM will have loaded the class and potentially processed method references which will fail if the class is not present.
To handle this scenario, a separate @Configuration
class can be used to isolate the condition, as shown in the following example:
@AutoConfiguration
// Some conditions ...
public class MyAutoConfiguration {
// Auto-configured beans ...
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(SomeService.class)
public static class SomeServiceConfiguration {
@Bean
@ConditionalOnMissingBean
public SomeService someService() {
return new SomeService();
}
}
}
@Configuration(proxyBeanMethods = false)
// Some conditions ...
class MyAutoConfiguration {
// Auto-configured beans ...
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(SomeService::class)
class SomeServiceConfiguration {
@Bean
@ConditionalOnMissingBean
fun someService(): SomeService {
return SomeService()
}
}
}
If you use @ConditionalOnClass or @ConditionalOnMissingClass as a part of a meta-annotation to compose your own composed annotations, you must use name as referring to the class in such a case is not handled.
|
Bean Conditions
The @ConditionalOnBean
and @ConditionalOnMissingBean
annotations let a bean be included based on the presence or absence of specific beans.
You can use the value
attribute to specify beans by type or name
to specify beans by name.
The search
attribute lets you limit the ApplicationContext
hierarchy that should be considered when searching for beans.
When placed on a @Bean
method, the target type defaults to the return type of the method, as shown in the following example:
@AutoConfiguration
public class MyAutoConfiguration {
@Bean
@ConditionalOnMissingBean
public SomeService someService() {
return new SomeService();
}
}
@Configuration(proxyBeanMethods = false)
class MyAutoConfiguration {
@Bean
@ConditionalOnMissingBean
fun someService(): SomeService {
return SomeService()
}
}
In the preceding example, the someService
bean is going to be created if no bean of type SomeService
is already contained in the ApplicationContext
.
You need to be very careful about the order in which bean definitions are added, as these conditions are evaluated based on what has been processed so far.
For this reason, we recommend using only @ConditionalOnBean and @ConditionalOnMissingBean annotations on auto-configuration classes (since these are guaranteed to load after any user-defined bean definitions have been added).
|
@ConditionalOnBean and @ConditionalOnMissingBean do not prevent @Configuration classes from being created.
The only difference between using these conditions at the class level and marking each contained @Bean method with the annotation is that the former prevents registration of the @Configuration class as a bean if the condition does not match.
|
When declaring a @Bean method, provide as much type information as possible in the method’s return type.
For example, if your bean’s concrete class implements an interface the bean method’s return type should be the concrete class and not the interface.
Providing as much type information as possible in @Bean methods is particularly important when using bean conditions as their evaluation can only rely upon to type information that is available in the method signature.
|
Property Conditions
The @ConditionalOnProperty
annotation lets configuration be included based on a Spring Environment property.
Use the prefix
and name
attributes to specify the property that should be checked.
By default, any property that exists and is not equal to false
is matched.
You can also create more advanced checks by using the havingValue
and matchIfMissing
attributes.
Resource Conditions
The @ConditionalOnResource
annotation lets configuration be included only when a specific resource is present.
Resources can be specified by using the usual Spring conventions, as shown in the following example: file:/home/user/test.dat
.
Web Application Conditions
The @ConditionalOnWebApplication
and @ConditionalOnNotWebApplication
annotations let configuration be included depending on whether the application is a web application.
A servlet-based web application is any application that uses a Spring WebApplicationContext
, defines a session
scope, or has a ConfigurableWebEnvironment
.
A reactive web application is any application that uses a ReactiveWebApplicationContext
, or has a ConfigurableReactiveWebEnvironment
.
The @ConditionalOnWarDeployment
and @ConditionalOnNotWarDeployment
annotations let configuration be included depending on whether the application is a traditional WAR application that is deployed to a servlet container.
This condition will not match for applications that are run with an embedded web server.
SpEL Expression Conditions
The @ConditionalOnExpression
annotation lets configuration be included based on the result of a SpEL expression.
Referencing a bean in the expression will cause that bean to be initialized very early in context refresh processing. As a result, the bean won’t be eligible for post-processing (such as configuration properties binding) and its state may be incomplete. |
7.12.4. Testing your Auto-configuration
An auto-configuration can be affected by many factors: user configuration (@Bean
definition and Environment
customization), condition evaluation (presence of a particular library), and others.
Concretely, each test should create a well defined ApplicationContext
that represents a combination of those customizations.
ApplicationContextRunner
provides a great way to achieve that.
ApplicationContextRunner doesn’t work when running the tests in a native image.
|
ApplicationContextRunner
is usually defined as a field of the test class to gather the base, common configuration.
The following example makes sure that MyServiceAutoConfiguration
is always invoked:
private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
.withConfiguration(AutoConfigurations.of(MyServiceAutoConfiguration.class));
val contextRunner = ApplicationContextRunner()
.withConfiguration(AutoConfigurations.of(MyServiceAutoConfiguration::class.java))
If multiple auto-configurations have to be defined, there is no need to order their declarations as they are invoked in the exact same order as when running the application. |
Each test can use the runner to represent a particular use case.
For instance, the sample below invokes a user configuration (UserConfiguration
) and checks that the auto-configuration backs off properly.
Invoking run
provides a callback context that can be used with AssertJ
.
@Test
void defaultServiceBacksOff() {
this.contextRunner.withUserConfiguration(UserConfiguration.class).run((context) -> {
assertThat(context).hasSingleBean(MyService.class);
assertThat(context).getBean("myCustomService").isSameAs(context.getBean(MyService.class));
});
}
@Configuration(proxyBeanMethods = false)
static class UserConfiguration {
@Bean
MyService myCustomService() {
return new MyService("mine");
}
}
@Test
fun defaultServiceBacksOff() {
contextRunner.withUserConfiguration(UserConfiguration::class.java)
.run { context: AssertableApplicationContext ->
assertThat(context).hasSingleBean(MyService::class.java)
assertThat(context).getBean("myCustomService")
.isSameAs(context.getBean(MyService::class.java))
}
}
@Configuration(proxyBeanMethods = false)
internal class UserConfiguration {
@Bean
fun myCustomService(): MyService {
return MyService("mine")
}
}
It is also possible to easily customize the Environment
, as shown in the following example:
@Test
void serviceNameCanBeConfigured() {
this.contextRunner.withPropertyValues("user.name=test123").run((context) -> {
assertThat(context).hasSingleBean(MyService.class);
assertThat(context.getBean(MyService.class).getName()).isEqualTo("test123");
});
}
@Test
fun serviceNameCanBeConfigured() {
contextRunner.withPropertyValues("user.name=test123").run { context: AssertableApplicationContext ->
assertThat(context).hasSingleBean(MyService::class.java)
assertThat(context.getBean(MyService::class.java).name).isEqualTo("test123")
}
}
The runner can also be used to display the ConditionEvaluationReport
.
The report can be printed at INFO
or DEBUG
level.
The following example shows how to use the ConditionEvaluationReportLoggingListener
to print the report in auto-configuration tests.
class MyConditionEvaluationReportingTests {
@Test
void autoConfigTest() {
new ApplicationContextRunner()
.withInitializer(ConditionEvaluationReportLoggingListener.forLogLevel(LogLevel.INFO))
.run((context) -> {
// Test something...
});
}
}
class MyConditionEvaluationReportingTests {
@Test
fun autoConfigTest() {
ApplicationContextRunner()
.withInitializer(ConditionEvaluationReportLoggingListener.forLogLevel(LogLevel.INFO))
.run { context: AssertableApplicationContext? -> }
}
}
Simulating a Web Context
If you need to test an auto-configuration that only operates in a servlet or reactive web application context, use the WebApplicationContextRunner
or ReactiveWebApplicationContextRunner
respectively.
Overriding the Classpath
It is also possible to test what happens when a particular class and/or package is not present at runtime.
Spring Boot ships with a FilteredClassLoader
that can easily be used by the runner.
In the following example, we assert that if MyService
is not present, the auto-configuration is properly disabled:
@Test
void serviceIsIgnoredIfLibraryIsNotPresent() {
this.contextRunner.withClassLoader(new FilteredClassLoader(MyService.class))
.run((context) -> assertThat(context).doesNotHaveBean("myService"));
}
@Test
fun serviceIsIgnoredIfLibraryIsNotPresent() {
contextRunner.withClassLoader(FilteredClassLoader(MyService::class.java))
.run { context: AssertableApplicationContext? ->
assertThat(context).doesNotHaveBean("myService")
}
}
7.12.5. Creating Your Own Starter
A typical Spring Boot starter contains code to auto-configure and customize the infrastructure of a given technology, let’s call that "acme". To make it easily extensible, a number of configuration keys in a dedicated namespace can be exposed to the environment. Finally, a single "starter" dependency is provided to help users get started as easily as possible.
Concretely, a custom starter can contain the following:
-
The
autoconfigure
module that contains the auto-configuration code for "acme". -
The
starter
module that provides a dependency to theautoconfigure
module as well as "acme" and any additional dependencies that are typically useful. In a nutshell, adding the starter should provide everything needed to start using that library.
This separation in two modules is in no way necessary.
If "acme" has several flavors, options or optional features, then it is better to separate the auto-configuration as you can clearly express the fact some features are optional.
Besides, you have the ability to craft a starter that provides an opinion about those optional dependencies.
At the same time, others can rely only on the autoconfigure
module and craft their own starter with different opinions.
If the auto-configuration is relatively straightforward and does not have optional features, merging the two modules in the starter is definitely an option.
Naming
You should make sure to provide a proper namespace for your starter.
Do not start your module names with spring-boot
, even if you use a different Maven groupId
.
We may offer official support for the thing you auto-configure in the future.
As a rule of thumb, you should name a combined module after the starter.
For example, assume that you are creating a starter for "acme" and that you name the auto-configure module acme-spring-boot
and the starter acme-spring-boot-starter
.
If you only have one module that combines the two, name it acme-spring-boot-starter
.
Configuration keys
If your starter provides configuration keys, use a unique namespace for them.
In particular, do not include your keys in the namespaces that Spring Boot uses (such as server
, management
, spring
, and so on).
If you use the same namespace, we may modify these namespaces in the future in ways that break your modules.
As a rule of thumb, prefix all your keys with a namespace that you own (for example acme
).
Make sure that configuration keys are documented by adding field javadoc for each property, as shown in the following example:
@ConfigurationProperties("acme")
public class AcmeProperties {
/**
* Whether to check the location of acme resources.
*/
private boolean checkLocation = true;
/**
* Timeout for establishing a connection to the acme server.
*/
private Duration loginTimeout = Duration.ofSeconds(3);
}
@ConfigurationProperties("acme")
class AcmeProperties(
/**
* Whether to check the location of acme resources.
*/
var isCheckLocation: Boolean = true,
/**
* Timeout for establishing a connection to the acme server.
*/
var loginTimeout:Duration = Duration.ofSeconds(3))
You should only use plain text with @ConfigurationProperties field Javadoc, since they are not processed before being added to the JSON.
|
Here are some rules we follow internally to make sure descriptions are consistent:
-
Do not start the description by "The" or "A".
-
For
boolean
types, start the description with "Whether" or "Enable". -
For collection-based types, start the description with "Comma-separated list"
-
Use
java.time.Duration
rather thanlong
and describe the default unit if it differs from milliseconds, such as "If a duration suffix is not specified, seconds will be used". -
Do not provide the default value in the description unless it has to be determined at runtime.
Make sure to trigger meta-data generation so that IDE assistance is available for your keys as well.
You may want to review the generated metadata (META-INF/spring-configuration-metadata.json
) to make sure your keys are properly documented.
Using your own starter in a compatible IDE is also a good idea to validate that quality of the metadata.
The “autoconfigure” Module
The autoconfigure
module contains everything that is necessary to get started with the library.
It may also contain configuration key definitions (such as @ConfigurationProperties
) and any callback interface that can be used to further customize how the components are initialized.
You should mark the dependencies to the library as optional so that you can include the autoconfigure module in your projects more easily.
If you do it that way, the library is not provided and, by default, Spring Boot backs off.
|
Spring Boot uses an annotation processor to collect the conditions on auto-configurations in a metadata file (META-INF/spring-autoconfigure-metadata.properties
).
If that file is present, it is used to eagerly filter auto-configurations that do not match, which will improve startup time.
When building with Maven, it is recommended to add the following dependency in a module that contains auto-configurations:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-autoconfigure-processor</artifactId>
<optional>true</optional>
</dependency>
If you have defined auto-configurations directly in your application, make sure to configure the spring-boot-maven-plugin
to prevent the repackage
goal from adding the dependency into the uber jar:
<project>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<excludes>
<exclude>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-autoconfigure-processor</artifactId>
</exclude>
</excludes>
</configuration>
</plugin>
</plugins>
</build>
</project>
With Gradle, the dependency should be declared in the annotationProcessor
configuration, as shown in the following example:
dependencies {
annotationProcessor "org.springframework.boot:spring-boot-autoconfigure-processor"
}
Starter Module
The starter is really an empty jar. Its only purpose is to provide the necessary dependencies to work with the library. You can think of it as an opinionated view of what is required to get started.
Do not make assumptions about the project in which your starter is added. If the library you are auto-configuring typically requires other starters, mention them as well. Providing a proper set of default dependencies may be hard if the number of optional dependencies is high, as you should avoid including dependencies that are unnecessary for a typical usage of the library. In other words, you should not include optional dependencies.
Either way, your starter must reference the core Spring Boot starter (spring-boot-starter ) directly or indirectly (there is no need to add it if your starter relies on another starter).
If a project is created with only your custom starter, Spring Boot’s core features will be honoured by the presence of the core starter.
|
7.13. Kotlin Support
Kotlin is a statically-typed language targeting the JVM (and other platforms) which allows writing concise and elegant code while providing interoperability with existing libraries written in Java.
Spring Boot provides Kotlin support by leveraging the support in other Spring projects such as Spring Framework, Spring Data, and Reactor. See the Spring Framework Kotlin support documentation for more information.
The easiest way to start with Spring Boot and Kotlin is to follow this comprehensive tutorial.
You can create new Kotlin projects by using start.spring.io.
Feel free to join the #spring channel of Kotlin Slack or ask a question with the spring
and kotlin
tags on Stack Overflow if you need support.
7.13.1. Requirements
Spring Boot requires at least Kotlin 1.7.x and manages a suitable Kotlin version through dependency management.
To use Kotlin, org.jetbrains.kotlin:kotlin-stdlib
and org.jetbrains.kotlin:kotlin-reflect
must be present on the classpath.
The kotlin-stdlib
variants kotlin-stdlib-jdk7
and kotlin-stdlib-jdk8
can also be used.
Since Kotlin classes are final by default, you are likely to want to configure kotlin-spring plugin in order to automatically open Spring-annotated classes so that they can be proxied.
Jackson’s Kotlin module is required for serializing / deserializing JSON data in Kotlin. It is automatically registered when found on the classpath. A warning message is logged if Jackson and Kotlin are present but the Jackson Kotlin module is not.
These dependencies and plugins are provided by default if one bootstraps a Kotlin project on start.spring.io. |
7.13.2. Null-safety
One of Kotlin’s key features is null-safety.
It deals with null
values at compile time rather than deferring the problem to runtime and encountering a NullPointerException
.
This helps to eliminate a common source of bugs without paying the cost of wrappers like Optional
.
Kotlin also allows using functional constructs with nullable values as described in this comprehensive guide to null-safety in Kotlin.
Although Java does not allow one to express null-safety in its type system, Spring Framework, Spring Data, and Reactor now provide null-safety of their API through tooling-friendly annotations. By default, types from Java APIs used in Kotlin are recognized as platform types for which null-checks are relaxed. Kotlin’s support for JSR 305 annotations combined with nullability annotations provide null-safety for the related Spring API in Kotlin.
The JSR 305 checks can be configured by adding the -Xjsr305
compiler flag with the following options: -Xjsr305={strict|warn|ignore}
.
The default behavior is the same as -Xjsr305=warn
.
The strict
value is required to have null-safety taken in account in Kotlin types inferred from Spring API but should be used with the knowledge that Spring API nullability declaration could evolve even between minor releases and more checks may be added in the future).
Generic type arguments, varargs and array elements nullability are not yet supported. See SPR-15942 for up-to-date information. Also be aware that Spring Boot’s own API is not yet annotated. |
7.13.3. Kotlin API
runApplication
Spring Boot provides an idiomatic way to run an application with runApplication<MyApplication>(*args)
as shown in the following example:
@SpringBootApplication
class MyApplication
fun main(args: Array<String>) {
runApplication<MyApplication>(*args)
}
This is a drop-in replacement for SpringApplication.run(MyApplication::class.java, *args)
.
It also allows customization of the application as shown in the following example:
runApplication<MyApplication>(*args) {
setBannerMode(OFF)
}
Extensions
Kotlin extensions provide the ability to extend existing classes with additional functionality. The Spring Boot Kotlin API makes use of these extensions to add new Kotlin specific conveniences to existing APIs.
TestRestTemplate
extensions, similar to those provided by Spring Framework for RestOperations
in Spring Framework, are provided.
Among other things, the extensions make it possible to take advantage of Kotlin reified type parameters.
7.13.4. Dependency management
In order to avoid mixing different versions of Kotlin dependencies on the classpath, Spring Boot imports the Kotlin BOM.
With Maven, the Kotlin version can be customized by setting the kotlin.version
property and plugin management is provided for kotlin-maven-plugin
.
With Gradle, the Spring Boot plugin automatically aligns the kotlin.version
with the version of the Kotlin plugin.
Spring Boot also manages the version of Coroutines dependencies by importing the Kotlin Coroutines BOM.
The version can be customized by setting the kotlin-coroutines.version
property.
org.jetbrains.kotlinx:kotlinx-coroutines-reactor dependency is provided by default if one bootstraps a Kotlin project with at least one reactive dependency on start.spring.io.
|
7.13.5. @ConfigurationProperties
@ConfigurationProperties
when used in combination with constructor binding supports classes with immutable val
properties as shown in the following example:
@ConfigurationProperties("example.kotlin")
data class KotlinExampleProperties(
val name: String,
val description: String,
val myService: MyService) {
data class MyService(
val apiToken: String,
val uri: URI
)
}
To generate your own metadata using the annotation processor, kapt should be configured with the spring-boot-configuration-processor dependency.
Note that some features (such as detecting the default value or deprecated items) are not working due to limitations in the model kapt provides.
|
7.13.6. Testing
While it is possible to use JUnit 4 to test Kotlin code, JUnit 5 is provided by default and is recommended.
JUnit 5 enables a test class to be instantiated once and reused for all of the class’s tests.
This makes it possible to use @BeforeAll
and @AfterAll
annotations on non-static methods, which is a good fit for Kotlin.
To mock Kotlin classes, MockK is recommended.
If you need the MockK
equivalent of the Mockito specific @MockBean
and @SpyBean
annotations, you can use SpringMockK which provides similar @MockkBean
and @SpykBean
annotations.
7.13.7. Resources
Further reading
-
Kotlin Slack (with a dedicated #spring channel)
-
Tutorial: building web applications with Spring Boot and Kotlin
-
A Geospatial Messenger with Kotlin, Spring Boot and PostgreSQL
Examples
-
spring-boot-kotlin-demo: regular Spring Boot + Spring Data JPA project
-
mixit: Spring Boot 2 + WebFlux + Reactive Spring Data MongoDB
-
spring-kotlin-fullstack: WebFlux Kotlin fullstack example with Kotlin2js for frontend instead of JavaScript or TypeScript
-
spring-petclinic-kotlin: Kotlin version of the Spring PetClinic Sample Application
-
spring-kotlin-deepdive: a step by step migration for Boot 1.0 + Java to Boot 2.0 + Kotlin
-
spring-boot-coroutines-demo: Coroutines sample project
7.14. SSL
Spring Boot provides the ability to configure SSL trust material that can be applied to several types of connections in order to support secure communications.
Configuration properties with the prefix spring.ssl.bundle
can be used to specify named sets of trust material and associated information.
7.14.1. Configuring SSL With Java KeyStore Files
Configuration properties with the prefix spring.ssl.bundle.jks
can be used to configure bundles of trust material created with the Java keytool
utility and stored in Java KeyStore files in the JKS or PKCS12 format.
Each bundle has a user-provided name that can be used to reference the bundle.
When used to secure an embedded web server, a keystore
is typically configured with a Java KeyStore containing a certificate and private key as shown in this example:
spring.ssl.bundle.jks.mybundle.key.alias=application
spring.ssl.bundle.jks.mybundle.keystore.location=classpath:application.p12
spring.ssl.bundle.jks.mybundle.keystore.password=secret
spring.ssl.bundle.jks.mybundle.keystore.type=PKCS12
spring:
ssl:
bundle:
jks:
mybundle:
key:
alias: "application"
keystore:
location: "classpath:application.p12"
password: "secret"
type: "PKCS12"
When used to secure a client-side connection, a truststore
is typically configured with a Java KeyStore containing the server certificate as shown in this example:
spring.ssl.bundle.jks.mybundle.truststore.location=classpath:server.p12
spring.ssl.bundle.jks.mybundle.truststore.password=secret
spring:
ssl:
bundle:
jks:
mybundle:
truststore:
location: "classpath:server.p12"
password: "secret"
See JksSslBundleProperties for the full set of supported properties.
7.14.2. Configuring SSL With PEM-encoded Certificates
Configuration properties with the prefix spring.ssl.bundle.pem
can be used to configure bundles of trust material in the form of PEM-encoded text.
Each bundle has a user-provided name that can be used to reference the bundle.
When used to secure an embedded web server, a keystore
is typically configured with a certificate and private key as shown in this example:
spring.ssl.bundle.pem.mybundle.keystore.certificate=classpath:application.crt
spring.ssl.bundle.pem.mybundle.keystore.private-key=classpath:application.key
spring:
ssl:
bundle:
pem:
mybundle:
keystore:
certificate: "classpath:application.crt"
private-key: "classpath:application.key"
When used to secure a client-side connection, a truststore
is typically configured with the server certificate as shown in this example:
spring.ssl.bundle.pem.mybundle.truststore.certificate=classpath:server.crt
spring:
ssl:
bundle:
pem:
mybundle:
truststore:
certificate: "classpath:server.crt"
PEM content can be used directly for both the The following example shows how a truststore certificate can be defined: Properties
Yaml
|
See PemSslBundleProperties for the full set of supported properties.
7.14.3. Applying SSL Bundles
Once configured using properties, SSL bundles can be referred to by name in configuration properties for various types of connections that are auto-configured by Spring Boot. See the sections on embedded web servers, data technologies, and REST clients for further information.
7.14.4. Using SSL Bundles
Spring Boot auto-configures a bean of type SslBundles
that provides access to each of the named bundles configured using the spring.ssl.bundle
properties.
An SslBundle
can be retrieved from the auto-configured SslBundles
bean and used to create objects that are used to configure SSL connectivity in client libraries.
The SslBundle
provides a layered approach of obtaining these SSL objects:
-
getStores()
provides access to the key store and trust storejava.security.KeyStore
instances as well as any required key store password. -
getManagers()
provides access to thejava.net.ssl.KeyManagerFactory
andjava.net.ssl.TrustManagerFactory
instances as well as thejava.net.ssl.KeyManager
andjava.net.ssl.TrustManager
arrays that they create. -
createSslContext()
provides a convenient way to obtain a newjava.net.ssl.SSLContext
instance.
In addition, the SslBundle
provides details about the key being used, the protocol to use and any option that should be applied to the SSL engine.
The following example shows retrieving an SslBundle
and using it to create an SSLContext
:
@Component
public class MyComponent {
public MyComponent(SslBundles sslBundles) {
SslBundle sslBundle = sslBundles.getBundle("mybundle");
SSLContext sslContext = sslBundle.createSslContext();
// do something with the created sslContext
}
}
@Component
class MyComponent(sslBundles: SslBundles) {
init {
val sslBundle = sslBundles.getBundle("mybundle")
val sslContext = sslBundle.createSslContext()
// do something with the created sslContext
}
}
7.14.5. Reloading SSL bundles
SSL bundles can be reloaded when the key material changes. The component consuming the bundle has to be compatible with reloadable SSL bundles. Currently the following components are compatible:
-
Tomcat web server
-
Netty web server
To enable reloading, you need to opt-in via a configuration property as shown in this example:
spring.ssl.bundle.pem.mybundle.reload-on-update=true
spring.ssl.bundle.pem.mybundle.keystore.certificate=file:/some/directory/application.crt
spring.ssl.bundle.pem.mybundle.keystore.private-key=file:/some/directory/application.key
spring:
ssl:
bundle:
pem:
mybundle:
reload-on-update: true
keystore:
certificate: "file:/some/directory/application.crt"
private-key: "file:/some/directory/application.key"
A file watcher is then watching the files and if they change, the SSL bundle will be reloaded. This in turn triggers a reload in the consuming component, e.g. Tomcat rotates the certificates in the SSL enabled connectors.
You can configure the quiet period (to make sure that there are no more changes) of the file watcher with the spring.ssl.bundle.watch.file.quiet-period
property.
7.15. What to Read Next
If you want to learn more about any of the classes discussed in this section, see the Spring Boot API documentation or you can browse the source code directly. If you have specific questions, see the how-to section.
If you are comfortable with Spring Boot’s core features, you can continue on and read about production-ready features.
8. Web
Spring Boot is well suited for web application development.
You can create a self-contained HTTP server by using embedded Tomcat, Jetty, Undertow, or Netty.
Most web applications use the spring-boot-starter-web
module to get up and running quickly.
You can also choose to build reactive web applications by using the spring-boot-starter-webflux
module.
If you have not yet developed a Spring Boot web application, you can follow the "Hello World!" example in the Getting started section.
8.1. Servlet Web Applications
If you want to build servlet-based web applications, you can take advantage of Spring Boot’s auto-configuration for Spring MVC or Jersey.
8.1.1. The “Spring Web MVC Framework”
The Spring Web MVC framework (often referred to as “Spring MVC”) is a rich “model view controller” web framework.
Spring MVC lets you create special @Controller
or @RestController
beans to handle incoming HTTP requests.
Methods in your controller are mapped to HTTP by using @RequestMapping
annotations.
The following code shows a typical @RestController
that serves JSON data:
@RestController
@RequestMapping("/users")
public class MyRestController {
private final UserRepository userRepository;
private final CustomerRepository customerRepository;
public MyRestController(UserRepository userRepository, CustomerRepository customerRepository) {
this.userRepository = userRepository;
this.customerRepository = customerRepository;
}
@GetMapping("/{userId}")
public User getUser(@PathVariable Long userId) {
return this.userRepository.findById(userId).get();
}
@GetMapping("/{userId}/customers")
public List<Customer> getUserCustomers(@PathVariable Long userId) {
return this.userRepository.findById(userId).map(this.customerRepository::findByUser).get();
}
@DeleteMapping("/{userId}")
public void deleteUser(@PathVariable Long userId) {
this.userRepository.deleteById(userId);
}
}
@RestController
@RequestMapping("/users")
class MyRestController(private val userRepository: UserRepository, private val customerRepository: CustomerRepository) {
@GetMapping("/{userId}")
fun getUser(@PathVariable userId: Long): User {
return userRepository.findById(userId).get()
}
@GetMapping("/{userId}/customers")
fun getUserCustomers(@PathVariable userId: Long): List<Customer> {
return userRepository.findById(userId).map(customerRepository::findByUser).get()
}
@DeleteMapping("/{userId}")
fun deleteUser(@PathVariable userId: Long) {
userRepository.deleteById(userId)
}
}
“WebMvc.fn”, the functional variant, separates the routing configuration from the actual handling of the requests, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyRoutingConfiguration {
private static final RequestPredicate ACCEPT_JSON = accept(MediaType.APPLICATION_JSON);
@Bean
public RouterFunction<ServerResponse> routerFunction(MyUserHandler userHandler) {
return route()
.GET("/{user}", ACCEPT_JSON, userHandler::getUser)
.GET("/{user}/customers", ACCEPT_JSON, userHandler::getUserCustomers)
.DELETE("/{user}", ACCEPT_JSON, userHandler::deleteUser)
.build();
}
}
@Configuration(proxyBeanMethods = false)
class MyRoutingConfiguration {
@Bean
fun routerFunction(userHandler: MyUserHandler): RouterFunction<ServerResponse> {
return RouterFunctions.route()
.GET("/{user}", ACCEPT_JSON, userHandler::getUser)
.GET("/{user}/customers", ACCEPT_JSON, userHandler::getUserCustomers)
.DELETE("/{user}", ACCEPT_JSON, userHandler::deleteUser)
.build()
}
companion object {
private val ACCEPT_JSON = accept(MediaType.APPLICATION_JSON)
}
}
@Component
public class MyUserHandler {
public ServerResponse getUser(ServerRequest request) {
...
return ServerResponse.ok().build();
}
public ServerResponse getUserCustomers(ServerRequest request) {
...
return ServerResponse.ok().build();
}
public ServerResponse deleteUser(ServerRequest request) {
...
return ServerResponse.ok().build();
}
}
@Component
class MyUserHandler {
fun getUser(request: ServerRequest?): ServerResponse {
return ServerResponse.ok().build()
}
fun getUserCustomers(request: ServerRequest?): ServerResponse {
return ServerResponse.ok().build()
}
fun deleteUser(request: ServerRequest?): ServerResponse {
return ServerResponse.ok().build()
}
}
Spring MVC is part of the core Spring Framework, and detailed information is available in the reference documentation. There are also several guides that cover Spring MVC available at spring.io/guides.
You can define as many RouterFunction beans as you like to modularize the definition of the router.
Beans can be ordered if you need to apply a precedence.
|
Spring MVC Auto-configuration
Spring Boot provides auto-configuration for Spring MVC that works well with most applications.
It replaces the need for @EnableWebMvc
and the two cannot be used together.
In addition to Spring MVC’s defaults, the auto-configuration provides the following features:
-
Inclusion of
ContentNegotiatingViewResolver
andBeanNameViewResolver
beans. -
Support for serving static resources, including support for WebJars (covered later in this document).
-
Automatic registration of
Converter
,GenericConverter
, andFormatter
beans. -
Support for
HttpMessageConverters
(covered later in this document). -
Automatic registration of
MessageCodesResolver
(covered later in this document). -
Static
index.html
support. -
Automatic use of a
ConfigurableWebBindingInitializer
bean (covered later in this document).
If you want to keep those Spring Boot MVC customizations and make more MVC customizations (interceptors, formatters, view controllers, and other features), you can add your own @Configuration
class of type WebMvcConfigurer
but without @EnableWebMvc
.
If you want to provide custom instances of RequestMappingHandlerMapping
, RequestMappingHandlerAdapter
, or ExceptionHandlerExceptionResolver
, and still keep the Spring Boot MVC customizations, you can declare a bean of type WebMvcRegistrations
and use it to provide custom instances of those components.
The custom instances will be subject to further initialization and configuration by Spring MVC.
To participate in, and if desired, override that subsequent processing, a WebMvcConfigurer
should be used.
If you do not want to use the auto-configuration and want to take complete control of Spring MVC, add your own @Configuration
annotated with @EnableWebMvc
.
Alternatively, add your own @Configuration
-annotated DelegatingWebMvcConfiguration
as described in the Javadoc of @EnableWebMvc
.
Spring MVC Conversion Service
Spring MVC uses a different ConversionService
to the one used to convert values from your application.properties
or application.yaml
file.
It means that Period
, Duration
and DataSize
converters are not available and that @DurationUnit
and @DataSizeUnit
annotations will be ignored.
If you want to customize the ConversionService
used by Spring MVC, you can provide a WebMvcConfigurer
bean with an addFormatters
method.
From this method you can register any converter that you like, or you can delegate to the static methods available on ApplicationConversionService
.
Conversion can also be customized using the spring.mvc.format.*
configuration properties.
When not configured, the following defaults are used:
Property | DateTimeFormatter |
---|---|
|
|
|
|
|
|
HttpMessageConverters
Spring MVC uses the HttpMessageConverter
interface to convert HTTP requests and responses.
Sensible defaults are included out of the box.
For example, objects can be automatically converted to JSON (by using the Jackson library) or XML (by using the Jackson XML extension, if available, or by using JAXB if the Jackson XML extension is not available).
By default, strings are encoded in UTF-8
.
If you need to add or customize converters, you can use Spring Boot’s HttpMessageConverters
class, as shown in the following listing:
@Configuration(proxyBeanMethods = false)
public class MyHttpMessageConvertersConfiguration {
@Bean
public HttpMessageConverters customConverters() {
HttpMessageConverter<?> additional = new AdditionalHttpMessageConverter();
HttpMessageConverter<?> another = new AnotherHttpMessageConverter();
return new HttpMessageConverters(additional, another);
}
}
@Configuration(proxyBeanMethods = false)
class MyHttpMessageConvertersConfiguration {
@Bean
fun customConverters(): HttpMessageConverters {
val additional: HttpMessageConverter<*> = AdditionalHttpMessageConverter()
val another: HttpMessageConverter<*> = AnotherHttpMessageConverter()
return HttpMessageConverters(additional, another)
}
}
Any HttpMessageConverter
bean that is present in the context is added to the list of converters.
You can also override default converters in the same way.
MessageCodesResolver
Spring MVC has a strategy for generating error codes for rendering error messages from binding errors: MessageCodesResolver
.
If you set the spring.mvc.message-codes-resolver-format
property PREFIX_ERROR_CODE
or POSTFIX_ERROR_CODE
, Spring Boot creates one for you (see the enumeration in DefaultMessageCodesResolver.Format
).
Static Content
By default, Spring Boot serves static content from a directory called /static
(or /public
or /resources
or /META-INF/resources
) in the classpath or from the root of the ServletContext
.
It uses the ResourceHttpRequestHandler
from Spring MVC so that you can modify that behavior by adding your own WebMvcConfigurer
and overriding the addResourceHandlers
method.
In a stand-alone web application, the default servlet from the container is not enabled.
It can be enabled using the server.servlet.register-default-servlet
property.
The default servlet acts as a fallback, serving content from the root of the ServletContext
if Spring decides not to handle it.
Most of the time, this does not happen (unless you modify the default MVC configuration), because Spring can always handle requests through the DispatcherServlet
.
By default, resources are mapped on /**
, but you can tune that with the spring.mvc.static-path-pattern
property.
For instance, relocating all resources to /resources/**
can be achieved as follows:
spring.mvc.static-path-pattern=/resources/**
spring:
mvc:
static-path-pattern: "/resources/**"
You can also customize the static resource locations by using the spring.web.resources.static-locations
property (replacing the default values with a list of directory locations).
The root servlet context path, "/"
, is automatically added as a location as well.
In addition to the “standard” static resource locations mentioned earlier, a special case is made for Webjars content.
By default, any resources with a path in /webjars/**
are served from jar files if they are packaged in the Webjars format.
The path can be customized with the spring.mvc.webjars-path-pattern
property.
Do not use the src/main/webapp directory if your application is packaged as a jar.
Although this directory is a common standard, it works only with war packaging, and it is silently ignored by most build tools if you generate a jar.
|
Spring Boot also supports the advanced resource handling features provided by Spring MVC, allowing use cases such as cache-busting static resources or using version agnostic URLs for Webjars.
To use version agnostic URLs for Webjars, add the webjars-locator-core
dependency.
Then declare your Webjar.
Using jQuery as an example, adding "/webjars/jquery/jquery.min.js"
results in "/webjars/jquery/x.y.z/jquery.min.js"
where x.y.z
is the Webjar version.
If you use JBoss, you need to declare the webjars-locator-jboss-vfs dependency instead of the webjars-locator-core .
Otherwise, all Webjars resolve as a 404 .
|
To use cache busting, the following configuration configures a cache busting solution for all static resources, effectively adding a content hash, such as <link href="/css/spring-2a2d595e6ed9a0b24f027f2b63b134d6.css"/>
, in URLs:
spring.web.resources.chain.strategy.content.enabled=true
spring.web.resources.chain.strategy.content.paths=/**
spring:
web:
resources:
chain:
strategy:
content:
enabled: true
paths: "/**"
Links to resources are rewritten in templates at runtime, thanks to a ResourceUrlEncodingFilter that is auto-configured for Thymeleaf and FreeMarker.
You should manually declare this filter when using JSPs.
Other template engines are currently not automatically supported but can be with custom template macros/helpers and the use of the ResourceUrlProvider .
|
When loading resources dynamically with, for example, a JavaScript module loader, renaming files is not an option. That is why other strategies are also supported and can be combined. A "fixed" strategy adds a static version string in the URL without changing the file name, as shown in the following example:
spring.web.resources.chain.strategy.content.enabled=true
spring.web.resources.chain.strategy.content.paths=/**
spring.web.resources.chain.strategy.fixed.enabled=true
spring.web.resources.chain.strategy.fixed.paths=/js/lib/
spring.web.resources.chain.strategy.fixed.version=v12
spring:
web:
resources:
chain:
strategy:
content:
enabled: true
paths: "/**"
fixed:
enabled: true
paths: "/js/lib/"
version: "v12"
With this configuration, JavaScript modules located under "/js/lib/"
use a fixed versioning strategy ("/v12/js/lib/mymodule.js"
), while other resources still use the content one (<link href="/css/spring-2a2d595e6ed9a0b24f027f2b63b134d6.css"/>
).
See WebProperties.Resources
for more supported options.
This feature has been thoroughly described in a dedicated blog post and in Spring Framework’s reference documentation. |
Welcome Page
Spring Boot supports both static and templated welcome pages.
It first looks for an index.html
file in the configured static content locations.
If one is not found, it then looks for an index
template.
If either is found, it is automatically used as the welcome page of the application.
This only acts as a fallback for actual index routes defined by the application.
The ordering is defined by the order of HandlerMapping
beans which is by default the following:
|
Endpoints declared with |
|
Endpoints declared in |
|
The welcome page support |
Custom Favicon
As with other static resources, Spring Boot checks for a favicon.ico
in the configured static content locations.
If such a file is present, it is automatically used as the favicon of the application.
Path Matching and Content Negotiation
Spring MVC can map incoming HTTP requests to handlers by looking at the request path and matching it to the mappings defined in your application (for example, @GetMapping
annotations on Controller methods).
Spring Boot chooses to disable suffix pattern matching by default, which means that requests like "GET /projects/spring-boot.json"
will not be matched to @GetMapping("/projects/spring-boot")
mappings.
This is considered as a best practice for Spring MVC applications.
This feature was mainly useful in the past for HTTP clients which did not send proper "Accept" request headers; we needed to make sure to send the correct Content Type to the client.
Nowadays, Content Negotiation is much more reliable.
There are other ways to deal with HTTP clients that do not consistently send proper "Accept" request headers.
Instead of using suffix matching, we can use a query parameter to ensure that requests like "GET /projects/spring-boot?format=json"
will be mapped to @GetMapping("/projects/spring-boot")
:
spring.mvc.contentnegotiation.favor-parameter=true
spring:
mvc:
contentnegotiation:
favor-parameter: true
Or if you prefer to use a different parameter name:
spring.mvc.contentnegotiation.favor-parameter=true
spring.mvc.contentnegotiation.parameter-name=myparam
spring:
mvc:
contentnegotiation:
favor-parameter: true
parameter-name: "myparam"
Most standard media types are supported out-of-the-box, but you can also define new ones:
spring.mvc.contentnegotiation.media-types.markdown=text/markdown
spring:
mvc:
contentnegotiation:
media-types:
markdown: "text/markdown"
As of Spring Framework 5.3, Spring MVC supports two strategies for matching request paths to controllers.
By default, Spring Boot uses the PathPatternParser
strategy.
PathPatternParser
is an optimized implementation but comes with some restrictions compared to the AntPathMatcher
strategy.
PathPatternParser
restricts usage of some path pattern variants.
It is also incompatible with configuring the DispatcherServlet
with a path prefix (spring.mvc.servlet.path
).
The strategy can be configured using the spring.mvc.pathmatch.matching-strategy
configuration property, as shown in the following example:
spring.mvc.pathmatch.matching-strategy=ant-path-matcher
spring:
mvc:
pathmatch:
matching-strategy: "ant-path-matcher"
By default, Spring MVC will send a 404 Not Found error response if a handler is not found for a request.
To have a NoHandlerFoundException
thrown instead, set configprop:spring.mvc.throw-exception-if-no-handler-found to true
.
Note that, by default, the serving of static content is mapped to /**
and will, therefore, provide a handler for all requests.
For a NoHandlerFoundException
to be thrown, you must also set spring.mvc.static-path-pattern
to a more specific value such as /resources/**
or set spring.web.resources.add-mappings
to false
to disable serving of static content entirely.
ConfigurableWebBindingInitializer
Spring MVC uses a WebBindingInitializer
to initialize a WebDataBinder
for a particular request.
If you create your own ConfigurableWebBindingInitializer
@Bean
, Spring Boot automatically configures Spring MVC to use it.
Template Engines
As well as REST web services, you can also use Spring MVC to serve dynamic HTML content. Spring MVC supports a variety of templating technologies, including Thymeleaf, FreeMarker, and JSPs. Also, many other templating engines include their own Spring MVC integrations.
Spring Boot includes auto-configuration support for the following templating engines:
If possible, JSPs should be avoided. There are several known limitations when using them with embedded servlet containers. |
When you use one of these templating engines with the default configuration, your templates are picked up automatically from src/main/resources/templates
.
Depending on how you run your application, your IDE may order the classpath differently. Running your application in the IDE from its main method results in a different ordering than when you run your application by using Maven or Gradle or from its packaged jar. This can cause Spring Boot to fail to find the expected template. If you have this problem, you can reorder the classpath in the IDE to place the module’s classes and resources first. |
Error Handling
By default, Spring Boot provides an /error
mapping that handles all errors in a sensible way, and it is registered as a “global” error page in the servlet container.
For machine clients, it produces a JSON response with details of the error, the HTTP status, and the exception message.
For browser clients, there is a “whitelabel” error view that renders the same data in HTML format (to customize it, add a View
that resolves to error
).
There are a number of server.error
properties that can be set if you want to customize the default error handling behavior.
See the “Server Properties” section of the Appendix.
To replace the default behavior completely, you can implement ErrorController
and register a bean definition of that type or add a bean of type ErrorAttributes
to use the existing mechanism but replace the contents.
The BasicErrorController can be used as a base class for a custom ErrorController .
This is particularly useful if you want to add a handler for a new content type (the default is to handle text/html specifically and provide a fallback for everything else).
To do so, extend BasicErrorController , add a public method with a @RequestMapping that has a produces attribute, and create a bean of your new type.
|
As of Spring Framework 6.0, RFC 7807 Problem Details is supported.
Spring MVC can produce custom error messages with the application/problem+json
media type, like:
{
"type": "https://example.org/problems/unknown-project",
"title": "Unknown project",
"status": 404,
"detail": "No project found for id 'spring-unknown'",
"instance": "/projects/spring-unknown"
}
This support can be enabled by setting spring.mvc.problemdetails.enabled
to true
.
You can also define a class annotated with @ControllerAdvice
to customize the JSON document to return for a particular controller and/or exception type, as shown in the following example:
@ControllerAdvice(basePackageClasses = SomeController.class)
public class MyControllerAdvice extends ResponseEntityExceptionHandler {
@ResponseBody
@ExceptionHandler(MyException.class)
public ResponseEntity<?> handleControllerException(HttpServletRequest request, Throwable ex) {
HttpStatus status = getStatus(request);
return new ResponseEntity<>(new MyErrorBody(status.value(), ex.getMessage()), status);
}
private HttpStatus getStatus(HttpServletRequest request) {
Integer code = (Integer) request.getAttribute(RequestDispatcher.ERROR_STATUS_CODE);
HttpStatus status = HttpStatus.resolve(code);
return (status != null) ? status : HttpStatus.INTERNAL_SERVER_ERROR;
}
}
@ControllerAdvice(basePackageClasses = [SomeController::class])
class MyControllerAdvice : ResponseEntityExceptionHandler() {
@ResponseBody
@ExceptionHandler(MyException::class)
fun handleControllerException(request: HttpServletRequest, ex: Throwable): ResponseEntity<*> {
val status = getStatus(request)
return ResponseEntity(MyErrorBody(status.value(), ex.message), status)
}
private fun getStatus(request: HttpServletRequest): HttpStatus {
val code = request.getAttribute(RequestDispatcher.ERROR_STATUS_CODE) as Int
val status = HttpStatus.resolve(code)
return status ?: HttpStatus.INTERNAL_SERVER_ERROR
}
}
In the preceding example, if MyException
is thrown by a controller defined in the same package as SomeController
, a JSON representation of the MyErrorBody
POJO is used instead of the ErrorAttributes
representation.
In some cases, errors handled at the controller level are not recorded by the metrics infrastructure. Applications can ensure that such exceptions are recorded with the request metrics by setting the handled exception as a request attribute:
@Controller
public class MyController {
@ExceptionHandler(CustomException.class)
String handleCustomException(HttpServletRequest request, CustomException ex) {
request.setAttribute(ErrorAttributes.ERROR_ATTRIBUTE, ex);
return "errorView";
}
}
@Controller
class MyController {
@ExceptionHandler(CustomException::class)
fun handleCustomException(request: HttpServletRequest, ex: CustomException?): String {
request.setAttribute(ErrorAttributes.ERROR_ATTRIBUTE, ex)
return "errorView"
}
}
Custom Error Pages
If you want to display a custom HTML error page for a given status code, you can add a file to an /error
directory.
Error pages can either be static HTML (that is, added under any of the static resource directories) or be built by using templates.
The name of the file should be the exact status code or a series mask.
For example, to map 404
to a static HTML file, your directory structure would be as follows:
src/ +- main/ +- java/ | + <source code> +- resources/ +- public/ +- error/ | +- 404.html +- <other public assets>
To map all 5xx
errors by using a FreeMarker template, your directory structure would be as follows:
src/ +- main/ +- java/ | + <source code> +- resources/ +- templates/ +- error/ | +- 5xx.ftlh +- <other templates>
For more complex mappings, you can also add beans that implement the ErrorViewResolver
interface, as shown in the following example:
public class MyErrorViewResolver implements ErrorViewResolver {
@Override
public ModelAndView resolveErrorView(HttpServletRequest request, HttpStatus status, Map<String, Object> model) {
// Use the request or status to optionally return a ModelAndView
if (status == HttpStatus.INSUFFICIENT_STORAGE) {
// We could add custom model values here
new ModelAndView("myview");
}
return null;
}
}
class MyErrorViewResolver : ErrorViewResolver {
override fun resolveErrorView(request: HttpServletRequest, status: HttpStatus,
model: Map<String, Any>): ModelAndView? {
// Use the request or status to optionally return a ModelAndView
if (status == HttpStatus.INSUFFICIENT_STORAGE) {
// We could add custom model values here
return ModelAndView("myview")
}
return null
}
}
You can also use regular Spring MVC features such as @ExceptionHandler
methods and @ControllerAdvice
.
The ErrorController
then picks up any unhandled exceptions.
Mapping Error Pages Outside of Spring MVC
For applications that do not use Spring MVC, you can use the ErrorPageRegistrar
interface to directly register ErrorPages
.
This abstraction works directly with the underlying embedded servlet container and works even if you do not have a Spring MVC DispatcherServlet
.
@Configuration(proxyBeanMethods = false)
public class MyErrorPagesConfiguration {
@Bean
public ErrorPageRegistrar errorPageRegistrar() {
return this::registerErrorPages;
}
private void registerErrorPages(ErrorPageRegistry registry) {
registry.addErrorPages(new ErrorPage(HttpStatus.BAD_REQUEST, "/400"));
}
}
@Configuration(proxyBeanMethods = false)
class MyErrorPagesConfiguration {
@Bean
fun errorPageRegistrar(): ErrorPageRegistrar {
return ErrorPageRegistrar { registry: ErrorPageRegistry -> registerErrorPages(registry) }
}
private fun registerErrorPages(registry: ErrorPageRegistry) {
registry.addErrorPages(ErrorPage(HttpStatus.BAD_REQUEST, "/400"))
}
}
If you register an ErrorPage with a path that ends up being handled by a Filter (as is common with some non-Spring web frameworks, like Jersey and Wicket), then the Filter has to be explicitly registered as an ERROR dispatcher, as shown in the following example:
|
@Configuration(proxyBeanMethods = false)
public class MyFilterConfiguration {
@Bean
public FilterRegistrationBean<MyFilter> myFilter() {
FilterRegistrationBean<MyFilter> registration = new FilterRegistrationBean<>(new MyFilter());
// ...
registration.setDispatcherTypes(EnumSet.allOf(DispatcherType.class));
return registration;
}
}
@Configuration(proxyBeanMethods = false)
class MyFilterConfiguration {
@Bean
fun myFilter(): FilterRegistrationBean<MyFilter> {
val registration = FilterRegistrationBean(MyFilter())
// ...
registration.setDispatcherTypes(EnumSet.allOf(DispatcherType::class.java))
return registration
}
}
Note that the default FilterRegistrationBean
does not include the ERROR
dispatcher type.
Error Handling in a WAR Deployment
When deployed to a servlet container, Spring Boot uses its error page filter to forward a request with an error status to the appropriate error page. This is necessary as the servlet specification does not provide an API for registering error pages. Depending on the container that you are deploying your war file to and the technologies that your application uses, some additional configuration may be required.
The error page filter can only forward the request to the correct error page if the response has not already been committed.
By default, WebSphere Application Server 8.0 and later commits the response upon successful completion of a servlet’s service method.
You should disable this behavior by setting com.ibm.ws.webcontainer.invokeFlushAfterService
to false
.
CORS Support
Cross-origin resource sharing (CORS) is a W3C specification implemented by most browsers that lets you specify in a flexible way what kind of cross-domain requests are authorized, instead of using some less secure and less powerful approaches such as IFRAME or JSONP.
As of version 4.2, Spring MVC supports CORS.
Using controller method CORS configuration with @CrossOrigin
annotations in your Spring Boot application does not require any specific configuration.
Global CORS configuration can be defined by registering a WebMvcConfigurer
bean with a customized addCorsMappings(CorsRegistry)
method, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyCorsConfiguration {
@Bean
public WebMvcConfigurer corsConfigurer() {
return new WebMvcConfigurer() {
@Override
public void addCorsMappings(CorsRegistry registry) {
registry.addMapping("/api/**");
}
};
}
}
@Configuration(proxyBeanMethods = false)
class MyCorsConfiguration {
@Bean
fun corsConfigurer(): WebMvcConfigurer {
return object : WebMvcConfigurer {
override fun addCorsMappings(registry: CorsRegistry) {
registry.addMapping("/api/**")
}
}
}
}
8.1.2. JAX-RS and Jersey
If you prefer the JAX-RS programming model for REST endpoints, you can use one of the available implementations instead of Spring MVC.
Jersey and Apache CXF work quite well out of the box.
CXF requires you to register its Servlet
or Filter
as a @Bean
in your application context.
Jersey has some native Spring support, so we also provide auto-configuration support for it in Spring Boot, together with a starter.
To get started with Jersey, include the spring-boot-starter-jersey
as a dependency and then you need one @Bean
of type ResourceConfig
in which you register all the endpoints, as shown in the following example:
@Component
public class MyJerseyConfig extends ResourceConfig {
public MyJerseyConfig() {
register(MyEndpoint.class);
}
}
Jersey’s support for scanning executable archives is rather limited.
For example, it cannot scan for endpoints in a package found in a fully executable jar file or in WEB-INF/classes when running an executable war file.
To avoid this limitation, the packages method should not be used, and endpoints should be registered individually by using the register method, as shown in the preceding example.
|
For more advanced customizations, you can also register an arbitrary number of beans that implement ResourceConfigCustomizer
.
All the registered endpoints should be @Components
with HTTP resource annotations (@GET
and others), as shown in the following example:
@Component
@Path("/hello")
public class MyEndpoint {
@GET
public String message() {
return "Hello";
}
}
Since the Endpoint
is a Spring @Component
, its lifecycle is managed by Spring and you can use the @Autowired
annotation to inject dependencies and use the @Value
annotation to inject external configuration.
By default, the Jersey servlet is registered and mapped to /*
.
You can change the mapping by adding @ApplicationPath
to your ResourceConfig
.
By default, Jersey is set up as a servlet in a @Bean
of type ServletRegistrationBean
named jerseyServletRegistration
.
By default, the servlet is initialized lazily, but you can customize that behavior by setting spring.jersey.servlet.load-on-startup
.
You can disable or override that bean by creating one of your own with the same name.
You can also use a filter instead of a servlet by setting spring.jersey.type=filter
(in which case, the @Bean
to replace or override is jerseyFilterRegistration
).
The filter has an @Order
, which you can set with spring.jersey.filter.order
.
When using Jersey as a filter, a servlet that will handle any requests that are not intercepted by Jersey must be present.
If your application does not contain such a servlet, you may want to enable the default servlet by setting server.servlet.register-default-servlet
to true
.
Both the servlet and the filter registrations can be given init parameters by using spring.jersey.init.*
to specify a map of properties.
8.1.3. Embedded Servlet Container Support
For servlet application, Spring Boot includes support for embedded Tomcat, Jetty, and Undertow servers.
Most developers use the appropriate “Starter” to obtain a fully configured instance.
By default, the embedded server listens for HTTP requests on port 8080
.
Servlets, Filters, and Listeners
When using an embedded servlet container, you can register servlets, filters, and all the listeners (such as HttpSessionListener
) from the servlet spec, either by using Spring beans or by scanning for servlet components.
Registering Servlets, Filters, and Listeners as Spring Beans
Any Servlet
, Filter
, or servlet *Listener
instance that is a Spring bean is registered with the embedded container.
This can be particularly convenient if you want to refer to a value from your application.properties
during configuration.
By default, if the context contains only a single Servlet, it is mapped to /
.
In the case of multiple servlet beans, the bean name is used as a path prefix.
Filters map to /*
.
If convention-based mapping is not flexible enough, you can use the ServletRegistrationBean
, FilterRegistrationBean
, and ServletListenerRegistrationBean
classes for complete control.
It is usually safe to leave filter beans unordered.
If a specific order is required, you should annotate the Filter
with @Order
or make it implement Ordered
.
You cannot configure the order of a Filter
by annotating its bean method with @Order
.
If you cannot change the Filter
class to add @Order
or implement Ordered
, you must define a FilterRegistrationBean
for the Filter
and set the registration bean’s order using the setOrder(int)
method.
Avoid configuring a filter that reads the request body at Ordered.HIGHEST_PRECEDENCE
, since it might go against the character encoding configuration of your application.
If a servlet filter wraps the request, it should be configured with an order that is less than or equal to OrderedFilter.REQUEST_WRAPPER_FILTER_MAX_ORDER
.
To see the order of every Filter in your application, enable debug level logging for the web logging group (logging.level.web=debug ).
Details of the registered filters, including their order and URL patterns, will then be logged at startup.
|
Take care when registering Filter beans since they are initialized very early in the application lifecycle.
If you need to register a Filter that interacts with other beans, consider using a DelegatingFilterProxyRegistrationBean instead.
|
Servlet Context Initialization
Embedded servlet containers do not directly execute the jakarta.servlet.ServletContainerInitializer
interface or Spring’s org.springframework.web.WebApplicationInitializer
interface.
This is an intentional design decision intended to reduce the risk that third party libraries designed to run inside a war may break Spring Boot applications.
If you need to perform servlet context initialization in a Spring Boot application, you should register a bean that implements the org.springframework.boot.web.servlet.ServletContextInitializer
interface.
The single onStartup
method provides access to the ServletContext
and, if necessary, can easily be used as an adapter to an existing WebApplicationInitializer
.
Scanning for Servlets, Filters, and listeners
When using an embedded container, automatic registration of classes annotated with @WebServlet
, @WebFilter
, and @WebListener
can be enabled by using @ServletComponentScan
.
@ServletComponentScan has no effect in a standalone container, where the container’s built-in discovery mechanisms are used instead.
|
The ServletWebServerApplicationContext
Under the hood, Spring Boot uses a different type of ApplicationContext
for embedded servlet container support.
The ServletWebServerApplicationContext
is a special type of WebApplicationContext
that bootstraps itself by searching for a single ServletWebServerFactory
bean.
Usually a TomcatServletWebServerFactory
, JettyServletWebServerFactory
, or UndertowServletWebServerFactory
has been auto-configured.
You usually do not need to be aware of these implementation classes.
Most applications are auto-configured, and the appropriate ApplicationContext and ServletWebServerFactory are created on your behalf.
|
In an embedded container setup, the ServletContext
is set as part of server startup which happens during application context initialization.
Because of this beans in the ApplicationContext
cannot be reliably initialized with a ServletContext
.
One way to get around this is to inject ApplicationContext
as a dependency of the bean and access the ServletContext
only when it is needed.
Another way is to use a callback once the server has started.
This can be done using an ApplicationListener
which listens for the ApplicationStartedEvent
as follows:
public class MyDemoBean implements ApplicationListener<ApplicationStartedEvent> {
private ServletContext servletContext;
@Override
public void onApplicationEvent(ApplicationStartedEvent event) {
ApplicationContext applicationContext = event.getApplicationContext();
this.servletContext = ((WebApplicationContext) applicationContext).getServletContext();
}
}
Customizing Embedded Servlet Containers
Common servlet container settings can be configured by using Spring Environment
properties.
Usually, you would define the properties in your application.properties
or application.yaml
file.
Common server settings include:
-
Network settings: Listen port for incoming HTTP requests (
server.port
), interface address to bind to (server.address
), and so on. -
Session settings: Whether the session is persistent (
server.servlet.session.persistent
), session timeout (server.servlet.session.timeout
), location of session data (server.servlet.session.store-dir
), and session-cookie configuration (server.servlet.session.cookie.*
). -
Error management: Location of the error page (
server.error.path
) and so on.
Spring Boot tries as much as possible to expose common settings, but this is not always possible.
For those cases, dedicated namespaces offer server-specific customizations (see server.tomcat
and server.undertow
).
For instance, access logs can be configured with specific features of the embedded servlet container.
See the ServerProperties class for a complete list.
|
SameSite Cookies
The SameSite
cookie attribute can be used by web browsers to control if and how cookies are submitted in cross-site requests.
The attribute is particularly relevant for modern web browsers which have started to change the default value that is used when the attribute is missing.
If you want to change the SameSite
attribute of your session cookie, you can use the server.servlet.session.cookie.same-site
property.
This property is supported by auto-configured Tomcat, Jetty and Undertow servers.
It is also used to configure Spring Session servlet based SessionRepository
beans.
For example, if you want your session cookie to have a SameSite
attribute of None
, you can add the following to your application.properties
or application.yaml
file:
server.servlet.session.cookie.same-site=none
server:
servlet:
session:
cookie:
same-site: "none"
If you want to change the SameSite
attribute on other cookies added to your HttpServletResponse
, you can use a CookieSameSiteSupplier
.
The CookieSameSiteSupplier
is passed a Cookie
and may return a SameSite
value, or null
.
There are a number of convenience factory and filter methods that you can use to quickly match specific cookies.
For example, adding the following bean will automatically apply a SameSite
of Lax
for all cookies with a name that matches the regular expression myapp.*
.
@Configuration(proxyBeanMethods = false)
public class MySameSiteConfiguration {
@Bean
public CookieSameSiteSupplier applicationCookieSameSiteSupplier() {
return CookieSameSiteSupplier.ofLax().whenHasNameMatching("myapp.*");
}
}
@Configuration(proxyBeanMethods = false)
class MySameSiteConfiguration {
@Bean
fun applicationCookieSameSiteSupplier(): CookieSameSiteSupplier {
return CookieSameSiteSupplier.ofLax().whenHasNameMatching("myapp.*")
}
}
Character Encoding
The character encoding behavior of the embedded servlet container for request and response handling can be configured using the server.servlet.encoding.*
configuration properties.
When a request’s Accept-Language
header indicates a locale for the request it will be automatically mapped to a charset by the servlet container.
Each container provides default locale to charset mappings and you should verify that they meet your application’s needs.
When they do not, use the server.servlet.encoding.mapping
configuration property to customize the mappings, as shown in the following example:
server.servlet.encoding.mapping.ko=UTF-8
server:
servlet:
encoding:
mapping:
ko: "UTF-8"
In the preceding example, the ko
(Korean) locale has been mapped to UTF-8
.
This is equivalent to a <locale-encoding-mapping-list>
entry in a web.xml
file of a traditional war deployment.
Programmatic Customization
If you need to programmatically configure your embedded servlet container, you can register a Spring bean that implements the WebServerFactoryCustomizer
interface.
WebServerFactoryCustomizer
provides access to the ConfigurableServletWebServerFactory
, which includes numerous customization setter methods.
The following example shows programmatically setting the port:
@Component
public class MyWebServerFactoryCustomizer implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory> {
@Override
public void customize(ConfigurableServletWebServerFactory server) {
server.setPort(9000);
}
}
@Component
class MyWebServerFactoryCustomizer : WebServerFactoryCustomizer<ConfigurableServletWebServerFactory> {
override fun customize(server: ConfigurableServletWebServerFactory) {
server.setPort(9000)
}
}
TomcatServletWebServerFactory
, JettyServletWebServerFactory
and UndertowServletWebServerFactory
are dedicated variants of ConfigurableServletWebServerFactory
that have additional customization setter methods for Tomcat, Jetty and Undertow respectively.
The following example shows how to customize TomcatServletWebServerFactory
that provides access to Tomcat-specific configuration options:
@Component
public class MyTomcatWebServerFactoryCustomizer implements WebServerFactoryCustomizer<TomcatServletWebServerFactory> {
@Override
public void customize(TomcatServletWebServerFactory server) {
server.addConnectorCustomizers((connector) -> connector.setAsyncTimeout(Duration.ofSeconds(20).toMillis()));
}
}
@Component
class MyTomcatWebServerFactoryCustomizer : WebServerFactoryCustomizer<TomcatServletWebServerFactory> {
override fun customize(server: TomcatServletWebServerFactory) {
server.addConnectorCustomizers({ connector -> connector.asyncTimeout = Duration.ofSeconds(20).toMillis() })
}
}
Customizing ConfigurableServletWebServerFactory Directly
For more advanced use cases that require you to extend from ServletWebServerFactory
, you can expose a bean of such type yourself.
Setters are provided for many configuration options. Several protected method “hooks” are also provided should you need to do something more exotic. See the source code documentation for details.
Auto-configured customizers are still applied on your custom factory, so use that option carefully. |
JSP Limitations
When running a Spring Boot application that uses an embedded servlet container (and is packaged as an executable archive), there are some limitations in the JSP support.
-
With Jetty and Tomcat, it should work if you use war packaging. An executable war will work when launched with
java -jar
, and will also be deployable to any standard container. JSPs are not supported when using an executable jar. -
Undertow does not support JSPs.
-
Creating a custom
error.jsp
page does not override the default view for error handling. Custom error pages should be used instead.
8.2. Reactive Web Applications
Spring Boot simplifies development of reactive web applications by providing auto-configuration for Spring Webflux.
8.2.1. The “Spring WebFlux Framework”
Spring WebFlux is the new reactive web framework introduced in Spring Framework 5.0. Unlike Spring MVC, it does not require the servlet API, is fully asynchronous and non-blocking, and implements the Reactive Streams specification through the Reactor project.
Spring WebFlux comes in two flavors: functional and annotation-based. The annotation-based one is quite close to the Spring MVC model, as shown in the following example:
@RestController
@RequestMapping("/users")
public class MyRestController {
private final UserRepository userRepository;
private final CustomerRepository customerRepository;
public MyRestController(UserRepository userRepository, CustomerRepository customerRepository) {
this.userRepository = userRepository;
this.customerRepository = customerRepository;
}
@GetMapping("/{userId}")
public Mono<User> getUser(@PathVariable Long userId) {
return this.userRepository.findById(userId);
}
@GetMapping("/{userId}/customers")
public Flux<Customer> getUserCustomers(@PathVariable Long userId) {
return this.userRepository.findById(userId).flatMapMany(this.customerRepository::findByUser);
}
@DeleteMapping("/{userId}")
public Mono<Void> deleteUser(@PathVariable Long userId) {
return this.userRepository.deleteById(userId);
}
}
@RestController
@RequestMapping("/users")
class MyRestController(private val userRepository: UserRepository, private val customerRepository: CustomerRepository) {
@GetMapping("/{userId}")
fun getUser(@PathVariable userId: Long): Mono<User?> {
return userRepository.findById(userId)
}
@GetMapping("/{userId}/customers")
fun getUserCustomers(@PathVariable userId: Long): Flux<Customer> {
return userRepository.findById(userId).flatMapMany { user: User? ->
customerRepository.findByUser(user)
}
}
@DeleteMapping("/{userId}")
fun deleteUser(@PathVariable userId: Long): Mono<Void> {
return userRepository.deleteById(userId)
}
}
WebFlux is part of the Spring Framework and detailed information is available in its reference documentation.
“WebFlux.fn”, the functional variant, separates the routing configuration from the actual handling of the requests, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyRoutingConfiguration {
private static final RequestPredicate ACCEPT_JSON = accept(MediaType.APPLICATION_JSON);
@Bean
public RouterFunction<ServerResponse> monoRouterFunction(MyUserHandler userHandler) {
return route()
.GET("/{user}", ACCEPT_JSON, userHandler::getUser)
.GET("/{user}/customers", ACCEPT_JSON, userHandler::getUserCustomers)
.DELETE("/{user}", ACCEPT_JSON, userHandler::deleteUser)
.build();
}
}
@Configuration(proxyBeanMethods = false)
class MyRoutingConfiguration {
@Bean
fun monoRouterFunction(userHandler: MyUserHandler): RouterFunction<ServerResponse> {
return RouterFunctions.route(
GET("/{user}").and(ACCEPT_JSON), userHandler::getUser).andRoute(
GET("/{user}/customers").and(ACCEPT_JSON), userHandler::getUserCustomers).andRoute(
DELETE("/{user}").and(ACCEPT_JSON), userHandler::deleteUser)
}
companion object {
private val ACCEPT_JSON = accept(MediaType.APPLICATION_JSON)
}
}
@Component
public class MyUserHandler {
public Mono<ServerResponse> getUser(ServerRequest request) {
...
}
public Mono<ServerResponse> getUserCustomers(ServerRequest request) {
...
}
public Mono<ServerResponse> deleteUser(ServerRequest request) {
...
}
}
@Component
class MyUserHandler {
fun getUser(request: ServerRequest?): Mono<ServerResponse> {
return ServerResponse.ok().build()
}
fun getUserCustomers(request: ServerRequest?): Mono<ServerResponse> {
return ServerResponse.ok().build()
}
fun deleteUser(request: ServerRequest?): Mono<ServerResponse> {
return ServerResponse.ok().build()
}
}
“WebFlux.fn” is part of the Spring Framework and detailed information is available in its reference documentation.
You can define as many RouterFunction beans as you like to modularize the definition of the router.
Beans can be ordered if you need to apply a precedence.
|
To get started, add the spring-boot-starter-webflux
module to your application.
Adding both spring-boot-starter-web and spring-boot-starter-webflux modules in your application results in Spring Boot auto-configuring Spring MVC, not WebFlux.
This behavior has been chosen because many Spring developers add spring-boot-starter-webflux to their Spring MVC application to use the reactive WebClient .
You can still enforce your choice by setting the chosen application type to SpringApplication.setWebApplicationType(WebApplicationType.REACTIVE) .
|
Spring WebFlux Auto-configuration
Spring Boot provides auto-configuration for Spring WebFlux that works well with most applications.
The auto-configuration adds the following features on top of Spring’s defaults:
-
Configuring codecs for
HttpMessageReader
andHttpMessageWriter
instances (described later in this document). -
Support for serving static resources, including support for WebJars (described later in this document).
If you want to keep Spring Boot WebFlux features and you want to add additional WebFlux configuration, you can add your own @Configuration
class of type WebFluxConfigurer
but without @EnableWebFlux
.
If you want to take complete control of Spring WebFlux, you can add your own @Configuration
annotated with @EnableWebFlux
.
Spring WebFlux Conversion Service
If you want to customize the ConversionService
used by Spring WebFlux, you can provide a WebFluxConfigurer
bean with an addFormatters
method.
Conversion can also be customized using the spring.webflux.format.*
configuration properties.
When not configured, the following defaults are used:
Property | DateTimeFormatter |
---|---|
|
|
|
|
|
|
HTTP Codecs with HttpMessageReaders and HttpMessageWriters
Spring WebFlux uses the HttpMessageReader
and HttpMessageWriter
interfaces to convert HTTP requests and responses.
They are configured with CodecConfigurer
to have sensible defaults by looking at the libraries available in your classpath.
Spring Boot provides dedicated configuration properties for codecs, spring.codec.*
.
It also applies further customization by using CodecCustomizer
instances.
For example, spring.jackson.*
configuration keys are applied to the Jackson codec.
If you need to add or customize codecs, you can create a custom CodecCustomizer
component, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyCodecsConfiguration {
@Bean
public CodecCustomizer myCodecCustomizer() {
return (configurer) -> {
configurer.registerDefaults(false);
configurer.customCodecs().register(new ServerSentEventHttpMessageReader());
// ...
};
}
}
class MyCodecsConfiguration {
@Bean
fun myCodecCustomizer(): CodecCustomizer {
return CodecCustomizer { configurer: CodecConfigurer ->
configurer.registerDefaults(false)
configurer.customCodecs().register(ServerSentEventHttpMessageReader())
}
}
}
You can also leverage Boot’s custom JSON serializers and deserializers.
Static Content
By default, Spring Boot serves static content from a directory called /static
(or /public
or /resources
or /META-INF/resources
) in the classpath.
It uses the ResourceWebHandler
from Spring WebFlux so that you can modify that behavior by adding your own WebFluxConfigurer
and overriding the addResourceHandlers
method.
By default, resources are mapped on /**
, but you can tune that by setting the spring.webflux.static-path-pattern
property.
For instance, relocating all resources to /resources/**
can be achieved as follows:
spring.webflux.static-path-pattern=/resources/**
spring:
webflux:
static-path-pattern: "/resources/**"
You can also customize the static resource locations by using spring.web.resources.static-locations
.
Doing so replaces the default values with a list of directory locations.
If you do so, the default welcome page detection switches to your custom locations.
So, if there is an index.html
in any of your locations on startup, it is the home page of the application.
In addition to the “standard” static resource locations listed earlier, a special case is made for Webjars content.
By default, any resources with a path in /webjars/**
are served from jar files if they are packaged in the Webjars format.
The path can be customized with the spring.webflux.webjars-path-pattern
property.
Spring WebFlux applications do not strictly depend on the servlet API, so they cannot be deployed as war files and do not use the src/main/webapp directory.
|
Welcome Page
Spring Boot supports both static and templated welcome pages.
It first looks for an index.html
file in the configured static content locations.
If one is not found, it then looks for an index
template.
If either is found, it is automatically used as the welcome page of the application.
This only acts as a fallback for actual index routes defined by the application.
The ordering is defined by the order of HandlerMapping
beans which is by default the following:
|
Endpoints declared with |
|
Endpoints declared in |
|
The welcome page support |
Template Engines
As well as REST web services, you can also use Spring WebFlux to serve dynamic HTML content. Spring WebFlux supports a variety of templating technologies, including Thymeleaf, FreeMarker, and Mustache.
Spring Boot includes auto-configuration support for the following templating engines:
When you use one of these templating engines with the default configuration, your templates are picked up automatically from src/main/resources/templates
.
Error Handling
Spring Boot provides a WebExceptionHandler
that handles all errors in a sensible way.
Its position in the processing order is immediately before the handlers provided by WebFlux, which are considered last.
For machine clients, it produces a JSON response with details of the error, the HTTP status, and the exception message.
For browser clients, there is a “whitelabel” error handler that renders the same data in HTML format.
You can also provide your own HTML templates to display errors (see the next section).
Before customizing error handling in Spring Boot directly, you can leverage the RFC 7807 Problem Details support in Spring WebFlux.
Spring WebFlux can produce custom error messages with the application/problem+json
media type, like:
{
"type": "https://example.org/problems/unknown-project",
"title": "Unknown project",
"status": 404,
"detail": "No project found for id 'spring-unknown'",
"instance": "/projects/spring-unknown"
}
This support can be enabled by setting spring.webflux.problemdetails.enabled
to true
.
The first step to customizing this feature often involves using the existing mechanism but replacing or augmenting the error contents.
For that, you can add a bean of type ErrorAttributes
.
To change the error handling behavior, you can implement ErrorWebExceptionHandler
and register a bean definition of that type.
Because an ErrorWebExceptionHandler
is quite low-level, Spring Boot also provides a convenient AbstractErrorWebExceptionHandler
to let you handle errors in a WebFlux functional way, as shown in the following example:
@Component
public class MyErrorWebExceptionHandler extends AbstractErrorWebExceptionHandler {
public MyErrorWebExceptionHandler(ErrorAttributes errorAttributes, WebProperties webProperties,
ApplicationContext applicationContext, ServerCodecConfigurer serverCodecConfigurer) {
super(errorAttributes, webProperties.getResources(), applicationContext);
setMessageReaders(serverCodecConfigurer.getReaders());
setMessageWriters(serverCodecConfigurer.getWriters());
}
@Override
protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) {
return RouterFunctions.route(this::acceptsXml, this::handleErrorAsXml);
}
private boolean acceptsXml(ServerRequest request) {
return request.headers().accept().contains(MediaType.APPLICATION_XML);
}
public Mono<ServerResponse> handleErrorAsXml(ServerRequest request) {
BodyBuilder builder = ServerResponse.status(HttpStatus.INTERNAL_SERVER_ERROR);
// ... additional builder calls
return builder.build();
}
}
@Component
class MyErrorWebExceptionHandler(
errorAttributes: ErrorAttributes, webProperties: WebProperties,
applicationContext: ApplicationContext, serverCodecConfigurer: ServerCodecConfigurer
) : AbstractErrorWebExceptionHandler(errorAttributes, webProperties.resources, applicationContext) {
init {
setMessageReaders(serverCodecConfigurer.readers)
setMessageWriters(serverCodecConfigurer.writers)
}
override fun getRoutingFunction(errorAttributes: ErrorAttributes): RouterFunction<ServerResponse> {
return RouterFunctions.route(this::acceptsXml, this::handleErrorAsXml)
}
private fun acceptsXml(request: ServerRequest): Boolean {
return request.headers().accept().contains(MediaType.APPLICATION_XML)
}
fun handleErrorAsXml(request: ServerRequest): Mono<ServerResponse> {
val builder = ServerResponse.status(HttpStatus.INTERNAL_SERVER_ERROR)
// ... additional builder calls
return builder.build()
}
}
For a more complete picture, you can also subclass DefaultErrorWebExceptionHandler
directly and override specific methods.
In some cases, errors handled at the controller or handler function level are not recorded by the metrics infrastructure. Applications can ensure that such exceptions are recorded with the request metrics by setting the handled exception as a request attribute:
@Controller
public class MyExceptionHandlingController {
@GetMapping("/profile")
public Rendering userProfile() {
// ...
throw new IllegalStateException();
}
@ExceptionHandler(IllegalStateException.class)
public Rendering handleIllegalState(ServerWebExchange exchange, IllegalStateException exc) {
exchange.getAttributes().putIfAbsent(ErrorAttributes.ERROR_ATTRIBUTE, exc);
return Rendering.view("errorView").modelAttribute("message", exc.getMessage()).build();
}
}
@Controller
class MyExceptionHandlingController {
@GetMapping("/profile")
fun userProfile(): Rendering {
// ...
throw IllegalStateException()
}
@ExceptionHandler(IllegalStateException::class)
fun handleIllegalState(exchange: ServerWebExchange, exc: IllegalStateException): Rendering {
exchange.attributes.putIfAbsent(ErrorAttributes.ERROR_ATTRIBUTE, exc)
return Rendering.view("errorView").modelAttribute("message", exc.message ?: "").build()
}
}
Custom Error Pages
If you want to display a custom HTML error page for a given status code, you can add views that resolve from error/*
, for example by adding files to a /error
directory.
Error pages can either be static HTML (that is, added under any of the static resource directories) or built with templates.
The name of the file should be the exact status code, a status code series mask, or error
for a default if nothing else matches.
Note that the path to the default error view is error/error
, whereas with Spring MVC the default error view is error
.
For example, to map 404
to a static HTML file, your directory structure would be as follows:
src/
+- main/
+- java/
| + <source code>
+- resources/
+- public/
+- error/
| +- 404.html
+- <other public assets>
To map all 5xx
errors by using a Mustache template, your directory structure would be as follows:
src/
+- main/
+- java/
| + <source code>
+- resources/
+- templates/
+- error/
| +- 5xx.mustache
+- <other templates>
Web Filters
Spring WebFlux provides a WebFilter
interface that can be implemented to filter HTTP request-response exchanges.
WebFilter
beans found in the application context will be automatically used to filter each exchange.
Where the order of the filters is important they can implement Ordered
or be annotated with @Order
.
Spring Boot auto-configuration may configure web filters for you.
When it does so, the orders shown in the following table will be used:
Web Filter | Order |
---|---|
|
|
|
|
8.2.2. Embedded Reactive Server Support
Spring Boot includes support for the following embedded reactive web servers: Reactor Netty, Tomcat, Jetty, and Undertow. Most developers use the appropriate “Starter” to obtain a fully configured instance. By default, the embedded server listens for HTTP requests on port 8080.
Customizing Reactive Servers
Common reactive web server settings can be configured by using Spring Environment
properties.
Usually, you would define the properties in your application.properties
or application.yaml
file.
Common server settings include:
-
Network settings: Listen port for incoming HTTP requests (
server.port
), interface address to bind to (server.address
), and so on. -
Error management: Location of the error page (
server.error.path
) and so on.
Spring Boot tries as much as possible to expose common settings, but this is not always possible.
For those cases, dedicated namespaces such as server.netty.*
offer server-specific customizations.
See the ServerProperties class for a complete list.
|
Programmatic Customization
If you need to programmatically configure your reactive web server, you can register a Spring bean that implements the WebServerFactoryCustomizer
interface.
WebServerFactoryCustomizer
provides access to the ConfigurableReactiveWebServerFactory
, which includes numerous customization setter methods.
The following example shows programmatically setting the port:
@Component
public class MyWebServerFactoryCustomizer implements WebServerFactoryCustomizer<ConfigurableReactiveWebServerFactory> {
@Override
public void customize(ConfigurableReactiveWebServerFactory server) {
server.setPort(9000);
}
}
@Component
class MyWebServerFactoryCustomizer : WebServerFactoryCustomizer<ConfigurableReactiveWebServerFactory> {
override fun customize(server: ConfigurableReactiveWebServerFactory) {
server.setPort(9000)
}
}
JettyReactiveWebServerFactory
, NettyReactiveWebServerFactory
, TomcatReactiveWebServerFactory
, and UndertowReactiveWebServerFactory
are dedicated variants of ConfigurableReactiveWebServerFactory
that have additional customization setter methods for Jetty, Reactor Netty, Tomcat, and Undertow respectively.
The following example shows how to customize NettyReactiveWebServerFactory
that provides access to Reactor Netty-specific configuration options:
@Component
public class MyNettyWebServerFactoryCustomizer implements WebServerFactoryCustomizer<NettyReactiveWebServerFactory> {
@Override
public void customize(NettyReactiveWebServerFactory factory) {
factory.addServerCustomizers((server) -> server.idleTimeout(Duration.ofSeconds(20)));
}
}
@Component
class MyNettyWebServerFactoryCustomizer : WebServerFactoryCustomizer<NettyReactiveWebServerFactory> {
override fun customize(factory: NettyReactiveWebServerFactory) {
factory.addServerCustomizers({ server -> server.idleTimeout(Duration.ofSeconds(20)) })
}
}
Customizing ConfigurableReactiveWebServerFactory Directly
For more advanced use cases that require you to extend from ReactiveWebServerFactory
, you can expose a bean of such type yourself.
Setters are provided for many configuration options. Several protected method “hooks” are also provided should you need to do something more exotic. See the source code documentation for details.
Auto-configured customizers are still applied on your custom factory, so use that option carefully. |
8.2.3. Reactive Server Resources Configuration
When auto-configuring a Reactor Netty or Jetty server, Spring Boot will create specific beans that will provide HTTP resources to the server instance: ReactorResourceFactory
or JettyResourceFactory
.
By default, those resources will be also shared with the Reactor Netty and Jetty clients for optimal performances, given:
-
the same technology is used for server and client
-
the client instance is built using the
WebClient.Builder
bean auto-configured by Spring Boot
Developers can override the resource configuration for Jetty and Reactor Netty by providing a custom ReactorResourceFactory
or JettyResourceFactory
bean - this will be applied to both clients and servers.
You can learn more about the resource configuration on the client side in the WebClient Runtime section.
8.3. Graceful Shutdown
Graceful shutdown is supported with all four embedded web servers (Jetty, Reactor Netty, Tomcat, and Undertow) and with both reactive and servlet-based web applications.
It occurs as part of closing the application context and is performed in the earliest phase of stopping SmartLifecycle
beans.
This stop processing uses a timeout which provides a grace period during which existing requests will be allowed to complete but no new requests will be permitted.
The exact way in which new requests are not permitted varies depending on the web server that is being used.
Jetty, Reactor Netty, and Tomcat will stop accepting requests at the network layer.
Undertow will accept requests but respond immediately with a service unavailable (503) response.
Graceful shutdown with Tomcat requires Tomcat 9.0.33 or later. |
To enable graceful shutdown, configure the server.shutdown
property, as shown in the following example:
server.shutdown=graceful
server:
shutdown: "graceful"
To configure the timeout period, configure the spring.lifecycle.timeout-per-shutdown-phase
property, as shown in the following example:
spring.lifecycle.timeout-per-shutdown-phase=20s
spring:
lifecycle:
timeout-per-shutdown-phase: "20s"
Using graceful shutdown with your IDE may not work properly if it does not send a proper SIGTERM signal.
See the documentation of your IDE for more details.
|
8.4. Spring Security
If Spring Security is on the classpath, then web applications are secured by default.
Spring Boot relies on Spring Security’s content-negotiation strategy to determine whether to use httpBasic
or formLogin
.
To add method-level security to a web application, you can also add @EnableGlobalMethodSecurity
with your desired settings.
Additional information can be found in the Spring Security Reference Guide.
The default UserDetailsService
has a single user.
The user name is user
, and the password is random and is printed at WARN level when the application starts, as shown in the following example:
Using generated security password: 78fa095d-3f4c-48b1-ad50-e24c31d5cf35 This generated password is for development use only. Your security configuration must be updated before running your application in production.
If you fine-tune your logging configuration, ensure that the org.springframework.boot.autoconfigure.security category is set to log WARN -level messages.
Otherwise, the default password is not printed.
|
You can change the username and password by providing a spring.security.user.name
and spring.security.user.password
.
The basic features you get by default in a web application are:
-
A
UserDetailsService
(orReactiveUserDetailsService
in case of a WebFlux application) bean with in-memory store and a single user with a generated password (seeSecurityProperties.User
for the properties of the user). -
Form-based login or HTTP Basic security (depending on the
Accept
header in the request) for the entire application (including actuator endpoints if actuator is on the classpath). -
A
DefaultAuthenticationEventPublisher
for publishing authentication events.
You can provide a different AuthenticationEventPublisher
by adding a bean for it.
8.4.1. MVC Security
The default security configuration is implemented in SecurityAutoConfiguration
and UserDetailsServiceAutoConfiguration
.
SecurityAutoConfiguration
imports SpringBootWebSecurityConfiguration
for web security and UserDetailsServiceAutoConfiguration
configures authentication, which is also relevant in non-web applications.
To switch off the default web application security configuration completely or to combine multiple Spring Security components such as OAuth2 Client and Resource Server, add a bean of type SecurityFilterChain
(doing so does not disable the UserDetailsService
configuration or Actuator’s security).
To also switch off the UserDetailsService
configuration, you can add a bean of type UserDetailsService
, AuthenticationProvider
, or AuthenticationManager
.
The auto-configuration of a UserDetailsService
will also back off any of the following Spring Security modules is on the classpath:
-
spring-security-oauth2-client
-
spring-security-oauth2-resource-server
-
spring-security-saml2-service-provider
To use UserDetailsService
in addition to one or more of these dependencies, define your own InMemoryUserDetailsManager
bean.
Access rules can be overridden by adding a custom SecurityFilterChain
bean.
Spring Boot provides convenience methods that can be used to override access rules for actuator endpoints and static resources.
EndpointRequest
can be used to create a RequestMatcher
that is based on the management.endpoints.web.base-path
property.
PathRequest
can be used to create a RequestMatcher
for resources in commonly used locations.
8.4.2. WebFlux Security
Similar to Spring MVC applications, you can secure your WebFlux applications by adding the spring-boot-starter-security
dependency.
The default security configuration is implemented in ReactiveSecurityAutoConfiguration
and UserDetailsServiceAutoConfiguration
.
ReactiveSecurityAutoConfiguration
imports WebFluxSecurityConfiguration
for web security and UserDetailsServiceAutoConfiguration
configures authentication, which is also relevant in non-web applications.
To switch off the default web application security configuration completely, you can add a bean of type WebFilterChainProxy
(doing so does not disable the UserDetailsService
configuration or Actuator’s security).
To also switch off the UserDetailsService
configuration, you can add a bean of type ReactiveUserDetailsService
or ReactiveAuthenticationManager
.
The auto-configuration will also back off when any of the following Spring Security modules is on the classpath:
-
spring-security-oauth2-client
-
spring-security-oauth2-resource-server
To use ReactiveUserDetailsService
in addition to one or more of these dependencies, define your own MapReactiveUserDetailsService
bean.
Access rules and the use of multiple Spring Security components such as OAuth 2 Client and Resource Server can be configured by adding a custom SecurityWebFilterChain
bean.
Spring Boot provides convenience methods that can be used to override access rules for actuator endpoints and static resources.
EndpointRequest
can be used to create a ServerWebExchangeMatcher
that is based on the management.endpoints.web.base-path
property.
PathRequest
can be used to create a ServerWebExchangeMatcher
for resources in commonly used locations.
For example, you can customize your security configuration by adding something like:
@Configuration(proxyBeanMethods = false)
public class MyWebFluxSecurityConfiguration {
@Bean
public SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) {
http.authorizeExchange((exchange) -> {
exchange.matchers(PathRequest.toStaticResources().atCommonLocations()).permitAll();
exchange.pathMatchers("/foo", "/bar").authenticated();
});
http.formLogin(withDefaults());
return http.build();
}
}
@Configuration(proxyBeanMethods = false)
class MyWebFluxSecurityConfiguration {
@Bean
fun springSecurityFilterChain(http: ServerHttpSecurity): SecurityWebFilterChain {
http.authorizeExchange { spec ->
spec.matchers(PathRequest.toStaticResources().atCommonLocations()).permitAll()
spec.pathMatchers("/foo", "/bar").authenticated()
}
http.formLogin(withDefaults())
return http.build()
}
}
8.4.3. OAuth2
OAuth2 is a widely used authorization framework that is supported by Spring.
Client
If you have spring-security-oauth2-client
on your classpath, you can take advantage of some auto-configuration to set up OAuth2/Open ID Connect clients.
This configuration makes use of the properties under OAuth2ClientProperties
.
The same properties are applicable to both servlet and reactive applications.
You can register multiple OAuth2 clients and providers under the spring.security.oauth2.client
prefix, as shown in the following example:
spring.security.oauth2.client.registration.my-login-client.client-id=abcd
spring.security.oauth2.client.registration.my-login-client.client-secret=password
spring.security.oauth2.client.registration.my-login-client.client-name=Client for OpenID Connect
spring.security.oauth2.client.registration.my-login-client.provider=my-oauth-provider
spring.security.oauth2.client.registration.my-login-client.scope=openid,profile,email,phone,address
spring.security.oauth2.client.registration.my-login-client.redirect-uri={baseUrl}/login/oauth2/code/{registrationId}
spring.security.oauth2.client.registration.my-login-client.client-authentication-method=client_secret_basic
spring.security.oauth2.client.registration.my-login-client.authorization-grant-type=authorization_code
spring.security.oauth2.client.registration.my-client-1.client-id=abcd
spring.security.oauth2.client.registration.my-client-1.client-secret=password
spring.security.oauth2.client.registration.my-client-1.client-name=Client for user scope
spring.security.oauth2.client.registration.my-client-1.provider=my-oauth-provider
spring.security.oauth2.client.registration.my-client-1.scope=user
spring.security.oauth2.client.registration.my-client-1.redirect-uri={baseUrl}/authorized/user
spring.security.oauth2.client.registration.my-client-1.client-authentication-method=client_secret_basic
spring.security.oauth2.client.registration.my-client-1.authorization-grant-type=authorization_code
spring.security.oauth2.client.registration.my-client-2.client-id=abcd
spring.security.oauth2.client.registration.my-client-2.client-secret=password
spring.security.oauth2.client.registration.my-client-2.client-name=Client for email scope
spring.security.oauth2.client.registration.my-client-2.provider=my-oauth-provider
spring.security.oauth2.client.registration.my-client-2.scope=email
spring.security.oauth2.client.registration.my-client-2.redirect-uri={baseUrl}/authorized/email
spring.security.oauth2.client.registration.my-client-2.client-authentication-method=client_secret_basic
spring.security.oauth2.client.registration.my-client-2.authorization-grant-type=authorization_code
spring.security.oauth2.client.provider.my-oauth-provider.authorization-uri=https://my-auth-server.com/oauth2/authorize
spring.security.oauth2.client.provider.my-oauth-provider.token-uri=https://my-auth-server.com/oauth2/token
spring.security.oauth2.client.provider.my-oauth-provider.user-info-uri=https://my-auth-server.com/userinfo
spring.security.oauth2.client.provider.my-oauth-provider.user-info-authentication-method=header
spring.security.oauth2.client.provider.my-oauth-provider.jwk-set-uri=https://my-auth-server.com/oauth2/jwks
spring.security.oauth2.client.provider.my-oauth-provider.user-name-attribute=name
spring:
security:
oauth2:
client:
registration:
my-login-client:
client-id: "abcd"
client-secret: "password"
client-name: "Client for OpenID Connect"
provider: "my-oauth-provider"
scope: "openid,profile,email,phone,address"
redirect-uri: "{baseUrl}/login/oauth2/code/{registrationId}"
client-authentication-method: "client_secret_basic"
authorization-grant-type: "authorization_code"
my-client-1:
client-id: "abcd"
client-secret: "password"
client-name: "Client for user scope"
provider: "my-oauth-provider"
scope: "user"
redirect-uri: "{baseUrl}/authorized/user"
client-authentication-method: "client_secret_basic"
authorization-grant-type: "authorization_code"
my-client-2:
client-id: "abcd"
client-secret: "password"
client-name: "Client for email scope"
provider: "my-oauth-provider"
scope: "email"
redirect-uri: "{baseUrl}/authorized/email"
client-authentication-method: "client_secret_basic"
authorization-grant-type: "authorization_code"
provider:
my-oauth-provider:
authorization-uri: "https://my-auth-server.com/oauth2/authorize"
token-uri: "https://my-auth-server.com/oauth2/token"
user-info-uri: "https://my-auth-server.com/userinfo"
user-info-authentication-method: "header"
jwk-set-uri: "https://my-auth-server.com/oauth2/jwks"
user-name-attribute: "name"
For OpenID Connect providers that support OpenID Connect discovery, the configuration can be further simplified.
The provider needs to be configured with an issuer-uri
which is the URI that it asserts as its Issuer Identifier.
For example, if the issuer-uri
provided is "https://example.com", then an "OpenID Provider Configuration Request" will be made to "https://example.com/.well-known/openid-configuration".
The result is expected to be an "OpenID Provider Configuration Response".
The following example shows how an OpenID Connect Provider can be configured with the issuer-uri
:
spring.security.oauth2.client.provider.oidc-provider.issuer-uri=https://dev-123456.oktapreview.com/oauth2/default/
spring:
security:
oauth2:
client:
provider:
oidc-provider:
issuer-uri: "https://dev-123456.oktapreview.com/oauth2/default/"
By default, Spring Security’s OAuth2LoginAuthenticationFilter
only processes URLs matching /login/oauth2/code/*
.
If you want to customize the redirect-uri
to use a different pattern, you need to provide configuration to process that custom pattern.
For example, for servlet applications, you can add your own SecurityFilterChain
that resembles the following:
@Configuration(proxyBeanMethods = false)
@EnableWebSecurity
public class MyOAuthClientConfiguration {
@Bean
public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
http
.authorizeHttpRequests((requests) -> requests
.anyRequest().authenticated()
)
.oauth2Login((login) -> login
.redirectionEndpoint((endpoint) -> endpoint
.baseUri("/login/oauth2/callback/*")
)
);
return http.build();
}
}
@Configuration(proxyBeanMethods = false)
@EnableWebSecurity
open class MyOAuthClientConfiguration {
@Bean
open fun securityFilterChain(http: HttpSecurity): SecurityFilterChain {
http {
authorizeHttpRequests {
authorize(anyRequest, authenticated)
}
oauth2Login {
redirectionEndpoint {
baseUri = "/login/oauth2/callback/*"
}
}
}
return http.build()
}
}
Spring Boot auto-configures an InMemoryOAuth2AuthorizedClientService which is used by Spring Security for the management of client registrations.
The InMemoryOAuth2AuthorizedClientService has limited capabilities and we recommend using it only for development environments.
For production environments, consider using a JdbcOAuth2AuthorizedClientService or creating your own implementation of OAuth2AuthorizedClientService .
|
OAuth2 Client Registration for Common Providers
For common OAuth2 and OpenID providers, including Google, Github, Facebook, and Okta, we provide a set of provider defaults (google
, github
, facebook
, and okta
, respectively).
If you do not need to customize these providers, you can set the provider
attribute to the one for which you need to infer defaults.
Also, if the key for the client registration matches a default supported provider, Spring Boot infers that as well.
In other words, the two configurations in the following example use the Google provider:
spring.security.oauth2.client.registration.my-client.client-id=abcd
spring.security.oauth2.client.registration.my-client.client-secret=password
spring.security.oauth2.client.registration.my-client.provider=google
spring.security.oauth2.client.registration.google.client-id=abcd
spring.security.oauth2.client.registration.google.client-secret=password
spring:
security:
oauth2:
client:
registration:
my-client:
client-id: "abcd"
client-secret: "password"
provider: "google"
google:
client-id: "abcd"
client-secret: "password"
Resource Server
If you have spring-security-oauth2-resource-server
on your classpath, Spring Boot can set up an OAuth2 Resource Server.
For JWT configuration, a JWK Set URI or OIDC Issuer URI needs to be specified, as shown in the following examples:
spring.security.oauth2.resourceserver.jwt.jwk-set-uri=https://example.com/oauth2/default/v1/keys
spring:
security:
oauth2:
resourceserver:
jwt:
jwk-set-uri: "https://example.com/oauth2/default/v1/keys"
spring.security.oauth2.resourceserver.jwt.issuer-uri=https://dev-123456.oktapreview.com/oauth2/default/
spring:
security:
oauth2:
resourceserver:
jwt:
issuer-uri: "https://dev-123456.oktapreview.com/oauth2/default/"
If the authorization server does not support a JWK Set URI, you can configure the resource server with the Public Key used for verifying the signature of the JWT.
This can be done using the spring.security.oauth2.resourceserver.jwt.public-key-location property, where the value needs to point to a file containing the public key in the PEM-encoded x509 format.
|
The spring.security.oauth2.resourceserver.jwt.audiences
property can be used to specify the expected values of the aud claim in JWTs.
For example, to require JWTs to contain an aud claim with the value my-audience
:
spring.security.oauth2.resourceserver.jwt.audiences[0]=my-audience
spring:
security:
oauth2:
resourceserver:
jwt:
audiences:
- "my-audience"
The same properties are applicable for both servlet and reactive applications.
Alternatively, you can define your own JwtDecoder
bean for servlet applications or a ReactiveJwtDecoder
for reactive applications.
In cases where opaque tokens are used instead of JWTs, you can configure the following properties to validate tokens through introspection:
spring.security.oauth2.resourceserver.opaquetoken.introspection-uri=https://example.com/check-token
spring.security.oauth2.resourceserver.opaquetoken.client-id=my-client-id
spring.security.oauth2.resourceserver.opaquetoken.client-secret=my-client-secret
spring:
security:
oauth2:
resourceserver:
opaquetoken:
introspection-uri: "https://example.com/check-token"
client-id: "my-client-id"
client-secret: "my-client-secret"
Again, the same properties are applicable for both servlet and reactive applications.
Alternatively, you can define your own OpaqueTokenIntrospector
bean for servlet applications or a ReactiveOpaqueTokenIntrospector
for reactive applications.
Authorization Server
If you have spring-security-oauth2-authorization-server
on your classpath, you can take advantage of some auto-configuration to set up a Servlet-based OAuth2 Authorization Server.
You can register multiple OAuth2 clients under the spring.security.oauth2.authorizationserver.client
prefix, as shown in the following example:
spring.security.oauth2.authorizationserver.client.my-client-1.registration.client-id=abcd
spring.security.oauth2.authorizationserver.client.my-client-1.registration.client-secret={noop}secret1
spring.security.oauth2.authorizationserver.client.my-client-1.registration.client-authentication-methods[0]=client_secret_basic
spring.security.oauth2.authorizationserver.client.my-client-1.registration.authorization-grant-types[0]=authorization_code
spring.security.oauth2.authorizationserver.client.my-client-1.registration.authorization-grant-types[1]=refresh_token
spring.security.oauth2.authorizationserver.client.my-client-1.registration.redirect-uris[0]=https://my-client-1.com/login/oauth2/code/abcd
spring.security.oauth2.authorizationserver.client.my-client-1.registration.redirect-uris[1]=https://my-client-1.com/authorized
spring.security.oauth2.authorizationserver.client.my-client-1.registration.scopes[0]=openid
spring.security.oauth2.authorizationserver.client.my-client-1.registration.scopes[1]=profile
spring.security.oauth2.authorizationserver.client.my-client-1.registration.scopes[2]=email
spring.security.oauth2.authorizationserver.client.my-client-1.registration.scopes[3]=phone
spring.security.oauth2.authorizationserver.client.my-client-1.registration.scopes[4]=address
spring.security.oauth2.authorizationserver.client.my-client-1.require-authorization-consent=true
spring.security.oauth2.authorizationserver.client.my-client-2.registration.client-id=efgh
spring.security.oauth2.authorizationserver.client.my-client-2.registration.client-secret={noop}secret2
spring.security.oauth2.authorizationserver.client.my-client-2.registration.client-authentication-methods[0]=client_secret_jwt
spring.security.oauth2.authorizationserver.client.my-client-2.registration.authorization-grant-types[0]=client_credentials
spring.security.oauth2.authorizationserver.client.my-client-2.registration.scopes[0]=user.read
spring.security.oauth2.authorizationserver.client.my-client-2.registration.scopes[1]=user.write
spring.security.oauth2.authorizationserver.client.my-client-2.jwk-set-uri=https://my-client-2.com/jwks
spring.security.oauth2.authorizationserver.client.my-client-2.token-endpoint-authentication-signing-algorithm=RS256
spring:
security:
oauth2:
authorizationserver:
client:
my-client-1:
registration:
client-id: "abcd"
client-secret: "{noop}secret1"
client-authentication-methods:
- "client_secret_basic"
authorization-grant-types:
- "authorization_code"
- "refresh_token"
redirect-uris:
- "https://my-client-1.com/login/oauth2/code/abcd"
- "https://my-client-1.com/authorized"
scopes:
- "openid"
- "profile"
- "email"
- "phone"
- "address"
require-authorization-consent: true
my-client-2:
registration:
client-id: "efgh"
client-secret: "{noop}secret2"
client-authentication-methods:
- "client_secret_jwt"
authorization-grant-types:
- "client_credentials"
scopes:
- "user.read"
- "user.write"
jwk-set-uri: "https://my-client-2.com/jwks"
token-endpoint-authentication-signing-algorithm: "RS256"
The client-secret property must be in a format that can be matched by the configured PasswordEncoder .
The default instance of PasswordEncoder is created via PasswordEncoderFactories.createDelegatingPasswordEncoder() .
|
The auto-configuration Spring Boot provides for Spring Authorization Server is designed for getting started quickly. Most applications will require customization and will want to define several beans to override auto-configuration.
The following components can be defined as beans to override auto-configuration specific to Spring Authorization Server:
-
RegisteredClientRepository
-
AuthorizationServerSettings
-
SecurityFilterChain
-
com.nimbusds.jose.jwk.source.JWKSource<com.nimbusds.jose.proc.SecurityContext>
-
JwtDecoder
Spring Boot auto-configures an InMemoryRegisteredClientRepository which is used by Spring Authorization Server for the management of registered clients.
The InMemoryRegisteredClientRepository has limited capabilities and we recommend using it only for development environments.
For production environments, consider using a JdbcRegisteredClientRepository or creating your own implementation of RegisteredClientRepository .
|
Additional information can be found in the Getting Started chapter of the Spring Authorization Server Reference Guide.
8.4.4. SAML 2.0
Relying Party
If you have spring-security-saml2-service-provider
on your classpath, you can take advantage of some auto-configuration to set up a SAML 2.0 Relying Party.
This configuration makes use of the properties under Saml2RelyingPartyProperties
.
A relying party registration represents a paired configuration between an Identity Provider, IDP, and a Service Provider, SP.
You can register multiple relying parties under the spring.security.saml2.relyingparty
prefix, as shown in the following example:
spring.security.saml2.relyingparty.registration.my-relying-party1.signing.credentials[0].private-key-location=path-to-private-key
spring.security.saml2.relyingparty.registration.my-relying-party1.signing.credentials[0].certificate-location=path-to-certificate
spring.security.saml2.relyingparty.registration.my-relying-party1.decryption.credentials[0].private-key-location=path-to-private-key
spring.security.saml2.relyingparty.registration.my-relying-party1.decryption.credentials[0].certificate-location=path-to-certificate
spring.security.saml2.relyingparty.registration.my-relying-party1.singlelogout.url=https://myapp/logout/saml2/slo
spring.security.saml2.relyingparty.registration.my-relying-party1.singlelogout.response-url=https://remoteidp2.slo.url
spring.security.saml2.relyingparty.registration.my-relying-party1.singlelogout.binding=POST
spring.security.saml2.relyingparty.registration.my-relying-party1.assertingparty.verification.credentials[0].certificate-location=path-to-verification-cert
spring.security.saml2.relyingparty.registration.my-relying-party1.assertingparty.entity-id=remote-idp-entity-id1
spring.security.saml2.relyingparty.registration.my-relying-party1.assertingparty.sso-url=https://remoteidp1.sso.url
spring.security.saml2.relyingparty.registration.my-relying-party2.signing.credentials[0].private-key-location=path-to-private-key
spring.security.saml2.relyingparty.registration.my-relying-party2.signing.credentials[0].certificate-location=path-to-certificate
spring.security.saml2.relyingparty.registration.my-relying-party2.decryption.credentials[0].private-key-location=path-to-private-key
spring.security.saml2.relyingparty.registration.my-relying-party2.decryption.credentials[0].certificate-location=path-to-certificate
spring.security.saml2.relyingparty.registration.my-relying-party2.assertingparty.verification.credentials[0].certificate-location=path-to-other-verification-cert
spring.security.saml2.relyingparty.registration.my-relying-party2.assertingparty.entity-id=remote-idp-entity-id2
spring.security.saml2.relyingparty.registration.my-relying-party2.assertingparty.sso-url=https://remoteidp2.sso.url
spring.security.saml2.relyingparty.registration.my-relying-party2.assertingparty.singlelogout.url=https://remoteidp2.slo.url
spring.security.saml2.relyingparty.registration.my-relying-party2.assertingparty.singlelogout.response-url=https://myapp/logout/saml2/slo
spring.security.saml2.relyingparty.registration.my-relying-party2.assertingparty.singlelogout.binding=POST
spring:
security:
saml2:
relyingparty:
registration:
my-relying-party1:
signing:
credentials:
- private-key-location: "path-to-private-key"
certificate-location: "path-to-certificate"
decryption:
credentials:
- private-key-location: "path-to-private-key"
certificate-location: "path-to-certificate"
singlelogout:
url: "https://myapp/logout/saml2/slo"
response-url: "https://remoteidp2.slo.url"
binding: "POST"
assertingparty:
verification:
credentials:
- certificate-location: "path-to-verification-cert"
entity-id: "remote-idp-entity-id1"
sso-url: "https://remoteidp1.sso.url"
my-relying-party2:
signing:
credentials:
- private-key-location: "path-to-private-key"
certificate-location: "path-to-certificate"
decryption:
credentials:
- private-key-location: "path-to-private-key"
certificate-location: "path-to-certificate"
assertingparty:
verification:
credentials:
- certificate-location: "path-to-other-verification-cert"
entity-id: "remote-idp-entity-id2"
sso-url: "https://remoteidp2.sso.url"
singlelogout:
url: "https://remoteidp2.slo.url"
response-url: "https://myapp/logout/saml2/slo"
binding: "POST"
For SAML2 logout, by default, Spring Security’s Saml2LogoutRequestFilter
and Saml2LogoutResponseFilter
only process URLs matching /logout/saml2/slo
.
If you want to customize the url
to which AP-initiated logout requests get sent to or the response-url
to which an AP sends logout responses to, to use a different pattern, you need to provide configuration to process that custom pattern.
For example, for servlet applications, you can add your own SecurityFilterChain
that resembles the following:
@Configuration(proxyBeanMethods = false)
public class MySamlRelyingPartyConfiguration {
@Bean
public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
http.authorizeHttpRequests((requests) -> requests.anyRequest().authenticated());
http.saml2Login(withDefaults());
http.saml2Logout((saml2) -> saml2.logoutRequest((request) -> request.logoutUrl("/SLOService.saml2"))
.logoutResponse((response) -> response.logoutUrl("/SLOService.saml2")));
return http.build();
}
}
8.5. Spring Session
Spring Boot provides Spring Session auto-configuration for a wide range of data stores. When building a servlet web application, the following stores can be auto-configured:
-
Redis
-
JDBC
-
Hazelcast
-
MongoDB
Additionally, Spring Boot for Apache Geode provides auto-configuration for using Apache Geode as a session store.
The servlet auto-configuration replaces the need to use @Enable*HttpSession
.
If a single Spring Session module is present on the classpath, Spring Boot uses that store implementation automatically. If you have more than one implementation, Spring Boot uses the following order for choosing a specific implementation:
-
Redis
-
JDBC
-
Hazelcast
-
MongoDB
-
If none of Redis, JDBC, Hazelcast and MongoDB are available, we do not configure a
SessionRepository
.
When building a reactive web application, the following stores can be auto-configured:
-
Redis
-
MongoDB
The reactive auto-configuration replaces the need to use @Enable*WebSession
.
Similar to the servlet configuration, if you have more than one implementation, Spring Boot uses the following order for choosing a specific implementation:
-
Redis
-
MongoDB
-
If neither Redis nor MongoDB are available, we do not configure a
ReactiveSessionRepository
.
Each store has specific additional settings. For instance, it is possible to customize the name of the table for the JDBC store, as shown in the following example:
spring.session.jdbc.table-name=SESSIONS
spring:
session:
jdbc:
table-name: "SESSIONS"
For setting the timeout of the session you can use the spring.session.timeout
property.
If that property is not set with a servlet web application, the auto-configuration falls back to the value of server.servlet.session.timeout
.
You can take control over Spring Session’s configuration using @Enable*HttpSession
(servlet) or @Enable*WebSession
(reactive).
This will cause the auto-configuration to back off.
Spring Session can then be configured using the annotation’s attributes rather than the previously described configuration properties.
8.6. Spring for GraphQL
If you want to build GraphQL applications, you can take advantage of Spring Boot’s auto-configuration for Spring for GraphQL.
The Spring for GraphQL project is based on GraphQL Java.
You’ll need the spring-boot-starter-graphql
starter at a minimum.
Because GraphQL is transport-agnostic, you’ll also need to have one or more additional starters in your application to expose your GraphQL API over the web:
Starter | Transport | Implementation |
---|---|---|
|
HTTP |
Spring MVC |
|
WebSocket |
WebSocket for Servlet apps |
|
HTTP, WebSocket |
Spring WebFlux |
|
TCP, WebSocket |
Spring WebFlux on Reactor Netty |
8.6.1. GraphQL Schema
A Spring GraphQL application requires a defined schema at startup.
By default, you can write ".graphqls" or ".gqls" schema files under src/main/resources/graphql/**
and Spring Boot will pick them up automatically.
You can customize the locations with spring.graphql.schema.locations
and the file extensions with spring.graphql.schema.file-extensions
.
If you want Spring Boot to detect schema files in all your application modules and dependencies for that location,
you can set spring.graphql.schema.locations to "classpath*:graphql/**/" (note the classpath*: prefix).
|
In the following sections, we’ll consider this sample GraphQL schema, defining two types and two queries:
type Query {
greeting(name: String! = "Spring"): String!
project(slug: ID!): Project
}
""" A Project in the Spring portfolio """
type Project {
""" Unique string id used in URLs """
slug: ID!
""" Project name """
name: String!
""" URL of the git repository """
repositoryUrl: String!
""" Current support status """
status: ProjectStatus!
}
enum ProjectStatus {
""" Actively supported by the Spring team """
ACTIVE
""" Supported by the community """
COMMUNITY
""" Prototype, not officially supported yet """
INCUBATING
""" Project being retired, in maintenance mode """
ATTIC
""" End-Of-Lifed """
EOL
}
By default, field introspection will be allowed on the schema as it is required for tools such as GraphiQL.
If you wish to not expose information about the schema, you can disable introspection by setting spring.graphql.schema.introspection.enabled to false .
|
8.6.2. GraphQL RuntimeWiring
The GraphQL Java RuntimeWiring.Builder
can be used to register custom scalar types, directives, type resolvers, DataFetcher
, and more.
You can declare RuntimeWiringConfigurer
beans in your Spring config to get access to the RuntimeWiring.Builder
.
Spring Boot detects such beans and adds them to the GraphQlSource builder.
Typically, however, applications will not implement DataFetcher
directly and will instead create annotated controllers.
Spring Boot will automatically detect @Controller
classes with annotated handler methods and register those as DataFetcher
s.
Here’s a sample implementation for our greeting query with a @Controller
class:
@Controller
public class GreetingController {
@QueryMapping
public String greeting(@Argument String name) {
return "Hello, " + name + "!";
}
}
;
@Controller
class GreetingController {
@QueryMapping
fun greeting(@Argument name: String): String {
return "Hello, $name!"
}
}
8.6.3. Querydsl and QueryByExample Repositories Support
Spring Data offers support for both Querydsl and QueryByExample repositories.
Spring GraphQL can configure Querydsl and QueryByExample repositories as DataFetcher
.
Spring Data repositories annotated with @GraphQlRepository
and extending one of:
-
QuerydslPredicateExecutor
-
ReactiveQuerydslPredicateExecutor
-
QueryByExampleExecutor
-
ReactiveQueryByExampleExecutor
are detected by Spring Boot and considered as candidates for DataFetcher
for matching top-level queries.
8.6.4. Transports
HTTP and WebSocket
The GraphQL HTTP endpoint is at HTTP POST /graphql
by default.
The path can be customized with spring.graphql.path
.
The HTTP endpoint for both Spring MVC and Spring WebFlux is provided by a RouterFunction bean with an @Order of 0 .
If you define your own RouterFunction beans, you may want to add appropriate @Order annotations to ensure that they are sorted correctly.
|
The GraphQL WebSocket endpoint is off by default. To enable it:
-
For a Servlet application, add the WebSocket starter
spring-boot-starter-websocket
-
For a WebFlux application, no additional dependency is required
-
For both, the
spring.graphql.websocket.path
application property must be set
Spring GraphQL provides a Web Interception model.
This is quite useful for retrieving information from an HTTP request header and set it in the GraphQL context or fetching information from the same context and writing it to a response header.
With Spring Boot, you can declare a WebInterceptor
bean to have it registered with the web transport.
Spring MVC and Spring WebFlux support CORS (Cross-Origin Resource Sharing) requests. CORS is a critical part of the web config for GraphQL applications that are accessed from browsers using different domains.
Spring Boot supports many configuration properties under the spring.graphql.cors.*
namespace; here’s a short configuration sample:
spring.graphql.cors.allowed-origins=https://example.org
spring.graphql.cors.allowed-methods=GET,POST
spring.graphql.cors.max-age=1800s
spring:
graphql:
cors:
allowed-origins: "https://example.org"
allowed-methods: GET,POST
max-age: 1800s
RSocket
RSocket is also supported as a transport, on top of WebSocket or TCP.
Once the RSocket server is configured, we can configure our GraphQL handler on a particular route using spring.graphql.rsocket.mapping
.
For example, configuring that mapping as "graphql"
means we can use that as a route when sending requests with the RSocketGraphQlClient
.
Spring Boot auto-configures a RSocketGraphQlClient.Builder<?>
bean that you can inject in your components:
@Component
public class RSocketGraphQlClientExample {
private final RSocketGraphQlClient graphQlClient;
public RSocketGraphQlClientExample(RSocketGraphQlClient.Builder<?> builder) {
this.graphQlClient = builder.tcp("example.spring.io", 8181).route("graphql").build();
}
@Component
class RSocketGraphQlClientExample(private val builder: RSocketGraphQlClient.Builder<*>) {
And then send a request:
Mono<Book> book = this.graphQlClient.document("{ bookById(id: \"book-1\"){ id name pageCount author } }")
.retrieve("bookById")
.toEntity(Book.class);
val book = graphQlClient.document(
"""
{
bookById(id: "book-1"){
id
name
pageCount
author
}
}
"""
)
.retrieve("bookById").toEntity(Book::class.java)
8.6.5. Exception Handling
Spring GraphQL enables applications to register one or more Spring DataFetcherExceptionResolver
components that are invoked sequentially.
The Exception must be resolved to a list of graphql.GraphQLError
objects, see Spring GraphQL exception handling documentation.
Spring Boot will automatically detect DataFetcherExceptionResolver
beans and register them with the GraphQlSource.Builder
.
8.6.6. GraphiQL and Schema printer
Spring GraphQL offers infrastructure for helping developers when consuming or developing a GraphQL API.
Spring GraphQL ships with a default GraphiQL page that is exposed at "/graphiql"
by default.
This page is disabled by default and can be turned on with the spring.graphql.graphiql.enabled
property.
Many applications exposing such a page will prefer a custom build.
A default implementation is very useful during development, this is why it is exposed automatically with spring-boot-devtools
during development.
You can also choose to expose the GraphQL schema in text format at /graphql/schema
when the spring.graphql.schema.printer.enabled
property is enabled.
8.7. Spring HATEOAS
If you develop a RESTful API that makes use of hypermedia, Spring Boot provides auto-configuration for Spring HATEOAS that works well with most applications.
The auto-configuration replaces the need to use @EnableHypermediaSupport
and registers a number of beans to ease building hypermedia-based applications, including a LinkDiscoverers
(for client side support) and an ObjectMapper
configured to correctly marshal responses into the desired representation.
The ObjectMapper
is customized by setting the various spring.jackson.*
properties or, if one exists, by a Jackson2ObjectMapperBuilder
bean.
You can take control of Spring HATEOAS’s configuration by using @EnableHypermediaSupport
.
Note that doing so disables the ObjectMapper
customization described earlier.
spring-boot-starter-hateoas is specific to Spring MVC and should not be combined with Spring WebFlux.
In order to use Spring HATEOAS with Spring WebFlux, you can add a direct dependency on org.springframework.hateoas:spring-hateoas along with spring-boot-starter-webflux .
|
By default, requests that accept application/json
will receive an application/hal+json
response.
To disable this behavior set spring.hateoas.use-hal-as-default-json-media-type
to false
and define a HypermediaMappingInformation
or HalConfiguration
to configure Spring HATEOAS to meet the needs of your application and its clients.
8.8. What to Read Next
You should now have a good understanding of how to develop web applications with Spring Boot. The next few sections describe how Spring Boot integrates with various data technologies, messaging systems, and other IO capabilities. You can pick any of these based on your application’s needs.
9. Data
Spring Boot integrates with a number of data technologies, both SQL and NoSQL.
9.1. SQL Databases
The Spring Framework provides extensive support for working with SQL databases, from direct JDBC access using JdbcClient
or JdbcTemplate
to complete “object relational mapping” technologies such as Hibernate.
Spring Data provides an additional level of functionality: creating Repository
implementations directly from interfaces and using conventions to generate queries from your method names.
9.1.1. Configure a DataSource
Java’s javax.sql.DataSource
interface provides a standard method of working with database connections.
Traditionally, a DataSource
uses a URL
along with some credentials to establish a database connection.
See the “How-to” section for more advanced examples, typically to take full control over the configuration of the DataSource. |
Embedded Database Support
It is often convenient to develop applications by using an in-memory embedded database. Obviously, in-memory databases do not provide persistent storage. You need to populate your database when your application starts and be prepared to throw away data when your application ends.
The “How-to” section includes a section on how to initialize a database. |
Spring Boot can auto-configure embedded H2, HSQL, and Derby databases.
You need not provide any connection URLs.
You need only include a build dependency to the embedded database that you want to use.
If there are multiple embedded databases on the classpath, set the spring.datasource.embedded-database-connection
configuration property to control which one is used.
Setting the property to none
disables auto-configuration of an embedded database.
If you are using this feature in your tests, you may notice that the same database is reused by your whole test suite regardless of the number of application contexts that you use.
If you want to make sure that each context has a separate embedded database, you should set |
For example, the typical POM dependencies would be as follows:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>org.hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<scope>runtime</scope>
</dependency>
You need a dependency on spring-jdbc for an embedded database to be auto-configured.
In this example, it is pulled in transitively through spring-boot-starter-data-jpa .
|
If, for whatever reason, you do configure the connection URL for an embedded database, take care to ensure that the database’s automatic shutdown is disabled.
If you use H2, you should use DB_CLOSE_ON_EXIT=FALSE to do so.
If you use HSQLDB, you should ensure that shutdown=true is not used.
Disabling the database’s automatic shutdown lets Spring Boot control when the database is closed, thereby ensuring that it happens once access to the database is no longer needed.
|
Connection to a Production Database
Production database connections can also be auto-configured by using a pooling DataSource
.
DataSource Configuration
DataSource configuration is controlled by external configuration properties in spring.datasource.*
.
For example, you might declare the following section in application.properties
:
spring.datasource.url=jdbc:mysql://localhost/test
spring.datasource.username=dbuser
spring.datasource.password=dbpass
spring:
datasource:
url: "jdbc:mysql://localhost/test"
username: "dbuser"
password: "dbpass"
You should at least specify the URL by setting the spring.datasource.url property.
Otherwise, Spring Boot tries to auto-configure an embedded database.
|
Spring Boot can deduce the JDBC driver class for most databases from the URL.
If you need to specify a specific class, you can use the spring.datasource.driver-class-name property.
|
For a pooling DataSource to be created, we need to be able to verify that a valid Driver class is available, so we check for that before doing anything.
In other words, if you set spring.datasource.driver-class-name=com.mysql.jdbc.Driver , then that class has to be loadable.
|
See DataSourceProperties
for more of the supported options.
These are the standard options that work regardless of the actual implementation.
It is also possible to fine-tune implementation-specific settings by using their respective prefix (spring.datasource.hikari.*
, spring.datasource.tomcat.*
, spring.datasource.dbcp2.*
, and spring.datasource.oracleucp.*
).
See the documentation of the connection pool implementation you are using for more details.
For instance, if you use the Tomcat connection pool, you could customize many additional settings, as shown in the following example:
spring.datasource.tomcat.max-wait=10000
spring.datasource.tomcat.max-active=50
spring.datasource.tomcat.test-on-borrow=true
spring:
datasource:
tomcat:
max-wait: 10000
max-active: 50
test-on-borrow: true
This will set the pool to wait 10000ms before throwing an exception if no connection is available, limit the maximum number of connections to 50 and validate the connection before borrowing it from the pool.
Supported Connection Pools
Spring Boot uses the following algorithm for choosing a specific implementation:
-
We prefer HikariCP for its performance and concurrency. If HikariCP is available, we always choose it.
-
Otherwise, if the Tomcat pooling
DataSource
is available, we use it. -
Otherwise, if Commons DBCP2 is available, we use it.
-
If none of HikariCP, Tomcat, and DBCP2 are available and if Oracle UCP is available, we use it.
If you use the spring-boot-starter-jdbc or spring-boot-starter-data-jpa “starters”, you automatically get a dependency to HikariCP .
|
You can bypass that algorithm completely and specify the connection pool to use by setting the spring.datasource.type
property.
This is especially important if you run your application in a Tomcat container, as tomcat-jdbc
is provided by default.
Additional connection pools can always be configured manually, using DataSourceBuilder
.
If you define your own DataSource
bean, auto-configuration does not occur.
The following connection pools are supported by DataSourceBuilder
:
-
HikariCP
-
Tomcat pooling
Datasource
-
Commons DBCP2
-
Oracle UCP &
OracleDataSource
-
Spring Framework’s
SimpleDriverDataSource
-
H2
JdbcDataSource
-
PostgreSQL
PGSimpleDataSource
-
C3P0
Connection to a JNDI DataSource
If you deploy your Spring Boot application to an Application Server, you might want to configure and manage your DataSource by using your Application Server’s built-in features and access it by using JNDI.
The spring.datasource.jndi-name
property can be used as an alternative to the spring.datasource.url
, spring.datasource.username
, and spring.datasource.password
properties to access the DataSource
from a specific JNDI location.
For example, the following section in application.properties
shows how you can access a JBoss AS defined DataSource
:
spring.datasource.jndi-name=java:jboss/datasources/customers
spring:
datasource:
jndi-name: "java:jboss/datasources/customers"
9.1.2. Using JdbcTemplate
Spring’s JdbcTemplate
and NamedParameterJdbcTemplate
classes are auto-configured, and you can @Autowire
them directly into your own beans, as shown in the following example:
@Component
public class MyBean {
private final JdbcTemplate jdbcTemplate;
public MyBean(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
public void doSomething() {
this.jdbcTemplate ...
}
}
@Component
class MyBean(private val jdbcTemplate: JdbcTemplate) {
fun doSomething() {
jdbcTemplate.execute("delete from customer")
}
}
You can customize some properties of the template by using the spring.jdbc.template.*
properties, as shown in the following example:
spring.jdbc.template.max-rows=500
spring:
jdbc:
template:
max-rows: 500
The NamedParameterJdbcTemplate reuses the same JdbcTemplate instance behind the scenes.
If more than one JdbcTemplate is defined and no primary candidate exists, the NamedParameterJdbcTemplate is not auto-configured.
|
9.1.3. Using JdbcClient
Spring’s JdbcClient
is auto-configured based on the presence of a NamedParameterJdbcTemplate
.
You can inject it directly in your own beans as well, as shown in the following example:
@Component
public class MyBean {
private final JdbcClient jdbcClient;
public MyBean(JdbcClient jdbcClient) {
this.jdbcClient = jdbcClient;
}
public void doSomething() {
this.jdbcClient ...
}
}
@Component
class MyBean(private val jdbcClient: JdbcClient) {
fun doSomething() {
jdbcClient.sql("delete from customer").update()
}
}
If you rely on auto-configuration to create the underlying JdbcTemplate
, any customization using spring.jdbc.template.*
properties is taken into account in the client as well.
9.1.4. JPA and Spring Data JPA
The Java Persistence API is a standard technology that lets you “map” objects to relational databases.
The spring-boot-starter-data-jpa
POM provides a quick way to get started.
It provides the following key dependencies:
-
Hibernate: One of the most popular JPA implementations.
-
Spring Data JPA: Helps you to implement JPA-based repositories.
-
Spring ORM: Core ORM support from the Spring Framework.
We do not go into too many details of JPA or Spring Data here. You can follow the “Accessing Data with JPA” guide from spring.io and read the Spring Data JPA and Hibernate reference documentation. |
Entity Classes
Traditionally, JPA “Entity” classes are specified in a persistence.xml
file.
With Spring Boot, this file is not necessary and “Entity Scanning” is used instead.
By default the auto-configuration packages are scanned.
Any classes annotated with @Entity
, @Embeddable
, or @MappedSuperclass
are considered.
A typical entity class resembles the following example:
@Entity
public class City implements Serializable {
@Id
@GeneratedValue
private Long id;
@Column(nullable = false)
private String name;
@Column(nullable = false)
private String state;
// ... additional members, often include @OneToMany mappings
protected City() {
// no-args constructor required by JPA spec
// this one is protected since it should not be used directly
}
public City(String name, String state) {
this.name = name;
this.state = state;
}
public String getName() {
return this.name;
}
public String getState() {
return this.state;
}
// ... etc
}
@Entity
class City : Serializable {
@Id
@GeneratedValue
private val id: Long? = null
@Column(nullable = false)
var name: String? = null
private set
// ... etc
@Column(nullable = false)
var state: String? = null
private set
// ... additional members, often include @OneToMany mappings
protected constructor() {
// no-args constructor required by JPA spec
// this one is protected since it should not be used directly
}
constructor(name: String?, state: String?) {
this.name = name
this.state = state
}
}
You can customize entity scanning locations by using the @EntityScan annotation.
See the “Separate @Entity Definitions from Spring Configuration” how-to.
|
Spring Data JPA Repositories
Spring Data JPA repositories are interfaces that you can define to access data.
JPA queries are created automatically from your method names.
For example, a CityRepository
interface might declare a findAllByState(String state)
method to find all the cities in a given state.
For more complex queries, you can annotate your method with Spring Data’s Query
annotation.
Spring Data repositories usually extend from the Repository
or CrudRepository
interfaces.
If you use auto-configuration, the auto-configuration packages are searched for repositories.
You can customize the locations to look for repositories using @EnableJpaRepositories .
|
The following example shows a typical Spring Data repository interface definition:
public interface CityRepository extends Repository<City, Long> {
Page<City> findAll(Pageable pageable);
City findByNameAndStateAllIgnoringCase(String name, String state);
}
interface CityRepository : Repository<City?, Long?> {
fun findAll(pageable: Pageable?): Page<City?>?
fun findByNameAndStateAllIgnoringCase(name: String?, state: String?): City?
}
Spring Data JPA repositories support three different modes of bootstrapping: default, deferred, and lazy.
To enable deferred or lazy bootstrapping, set the spring.data.jpa.repositories.bootstrap-mode
property to deferred
or lazy
respectively.
When using deferred or lazy bootstrapping, the auto-configured EntityManagerFactoryBuilder
will use the context’s AsyncTaskExecutor
, if any, as the bootstrap executor.
If more than one exists, the one named applicationTaskExecutor
will be used.
When using deferred or lazy bootstrapping, make sure to defer any access to the JPA infrastructure after the application context bootstrap phase.
You can use |
We have barely scratched the surface of Spring Data JPA. For complete details, see the Spring Data JPA reference documentation. |
Spring Data Envers Repositories
If Spring Data Envers is available, JPA repositories are auto-configured to support typical Envers queries.
To use Spring Data Envers, make sure your repository extends from RevisionRepository
as shown in the following example:
public interface CountryRepository extends RevisionRepository<Country, Long, Integer>, Repository<Country, Long> {
Page<Country> findAll(Pageable pageable);
}
interface CountryRepository :
RevisionRepository<Country?, Long?, Int>,
Repository<Country?, Long?> {
fun findAll(pageable: Pageable?): Page<Country?>?
}
For more details, check the Spring Data Envers reference documentation. |
Creating and Dropping JPA Databases
By default, JPA databases are automatically created only if you use an embedded database (H2, HSQL, or Derby).
You can explicitly configure JPA settings by using spring.jpa.*
properties.
For example, to create and drop tables you can add the following line to your application.properties
:
spring.jpa.hibernate.ddl-auto=create-drop
spring:
jpa:
hibernate.ddl-auto: "create-drop"
Hibernate’s own internal property name for this (if you happen to remember it better) is hibernate.hbm2ddl.auto .
You can set it, along with other Hibernate native properties, by using spring.jpa.properties.* (the prefix is stripped before adding them to the entity manager).
The following line shows an example of setting JPA properties for Hibernate:
|
spring.jpa.properties.hibernate[globally_quoted_identifiers]=true
spring:
jpa:
properties:
hibernate:
"globally_quoted_identifiers": "true"
The line in the preceding example passes a value of true
for the hibernate.globally_quoted_identifiers
property to the Hibernate entity manager.
By default, the DDL execution (or validation) is deferred until the ApplicationContext
has started.
There is also a spring.jpa.generate-ddl
flag, but it is not used if Hibernate auto-configuration is active, because the ddl-auto
settings are more fine-grained.
Open EntityManager in View
If you are running a web application, Spring Boot by default registers OpenEntityManagerInViewInterceptor
to apply the “Open EntityManager in View” pattern, to allow for lazy loading in web views.
If you do not want this behavior, you should set spring.jpa.open-in-view
to false
in your application.properties
.
9.1.5. Spring Data JDBC
Spring Data includes repository support for JDBC and will automatically generate SQL for the methods on CrudRepository
.
For more advanced queries, a @Query
annotation is provided.
Spring Boot will auto-configure Spring Data’s JDBC repositories when the necessary dependencies are on the classpath.
They can be added to your project with a single dependency on spring-boot-starter-data-jdbc
.
If necessary, you can take control of Spring Data JDBC’s configuration by adding the @EnableJdbcRepositories
annotation or an AbstractJdbcConfiguration
subclass to your application.
For complete details of Spring Data JDBC, see the reference documentation. |
9.1.6. Using H2’s Web Console
The H2 database provides a browser-based console that Spring Boot can auto-configure for you. The console is auto-configured when the following conditions are met:
-
You are developing a servlet-based web application.
-
com.h2database:h2
is on the classpath. -
You are using Spring Boot’s developer tools.
If you are not using Spring Boot’s developer tools but would still like to make use of H2’s console, you can configure the spring.h2.console.enabled property with a value of true .
|
The H2 console is only intended for use during development, so you should take care to ensure that spring.h2.console.enabled is not set to true in production.
|
Changing the H2 Console’s Path
By default, the console is available at /h2-console
.
You can customize the console’s path by using the spring.h2.console.path
property.
Accessing the H2 Console in a Secured Application
H2 Console uses frames and, as it is intended for development only, does not implement CSRF protection measures. If your application uses Spring Security, you need to configure it to
-
disable CSRF protection for requests against the console,
-
set the header
X-Frame-Options
toSAMEORIGIN
on responses from the console.
More information on CSRF and the header X-Frame-Options can be found in the Spring Security Reference Guide.
In simple setups, a SecurityFilterChain
like the following can be used:
@Profile("dev")
@Configuration(proxyBeanMethods = false)
public class DevProfileSecurityConfiguration {
@Bean
@Order(Ordered.HIGHEST_PRECEDENCE)
SecurityFilterChain h2ConsoleSecurityFilterChain(HttpSecurity http) throws Exception {
http.securityMatcher(PathRequest.toH2Console());
http.authorizeHttpRequests(yourCustomAuthorization());
http.csrf((csrf) -> csrf.disable());
http.headers((headers) -> headers.frameOptions((frame) -> frame.sameOrigin()));
return http.build();
}
}
@Profile("dev")
@Configuration(proxyBeanMethods = false)
class DevProfileSecurityConfiguration {
@Bean
@Order(Ordered.HIGHEST_PRECEDENCE)
fun h2ConsoleSecurityFilterChain(http: HttpSecurity): SecurityFilterChain {
return http.authorizeHttpRequests(yourCustomAuthorization())
.csrf { csrf -> csrf.disable() }
.headers { headers -> headers.frameOptions { frameOptions -> frameOptions.sameOrigin() } }
.build()
}
}
The H2 console is only intended for use during development. In production, disabling CSRF protection or allowing frames for a website may create severe security risks. |
PathRequest.toH2Console() returns the correct request matcher also when the console’s path has been customized.
|
9.1.7. Using jOOQ
jOOQ Object Oriented Querying (jOOQ) is a popular product from Data Geekery which generates Java code from your database and lets you build type-safe SQL queries through its fluent API. Both the commercial and open source editions can be used with Spring Boot.
Code Generation
In order to use jOOQ type-safe queries, you need to generate Java classes from your database schema.
You can follow the instructions in the jOOQ user manual.
If you use the jooq-codegen-maven
plugin and you also use the spring-boot-starter-parent
“parent POM”, you can safely omit the plugin’s <version>
tag.
You can also use Spring Boot-defined version variables (such as h2.version
) to declare the plugin’s database dependency.
The following listing shows an example:
<plugin>
<groupId>org.jooq</groupId>
<artifactId>jooq-codegen-maven</artifactId>
<executions>
...
</executions>
<dependencies>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<version>${h2.version}</version>
</dependency>
</dependencies>
<configuration>
<jdbc>
<driver>org.h2.Driver</driver>
<url>jdbc:h2:~/yourdatabase</url>
</jdbc>
<generator>
...
</generator>
</configuration>
</plugin>
Using DSLContext
The fluent API offered by jOOQ is initiated through the org.jooq.DSLContext
interface.
Spring Boot auto-configures a DSLContext
as a Spring Bean and connects it to your application DataSource
.
To use the DSLContext
, you can inject it, as shown in the following example:
@Component
public class MyBean {
private final DSLContext create;
public MyBean(DSLContext dslContext) {
this.create = dslContext;
}
}
@Component
class MyBean(private val create: DSLContext) {
}
The jOOQ manual tends to use a variable named create to hold the DSLContext .
|
You can then use the DSLContext
to construct your queries, as shown in the following example:
public List<GregorianCalendar> authorsBornAfter1980() {
return this.create.selectFrom(AUTHOR)
.where(AUTHOR.DATE_OF_BIRTH.greaterThan(new GregorianCalendar(1980, 0, 1)))
.fetch(AUTHOR.DATE_OF_BIRTH);
fun authorsBornAfter1980(): List<GregorianCalendar> {
return create.selectFrom<Tables.TAuthorRecord>(Tables.AUTHOR)
.where(Tables.AUTHOR?.DATE_OF_BIRTH?.greaterThan(GregorianCalendar(1980, 0, 1)))
.fetch(Tables.AUTHOR?.DATE_OF_BIRTH)
}
jOOQ SQL Dialect
Unless the spring.jooq.sql-dialect
property has been configured, Spring Boot determines the SQL dialect to use for your datasource.
If Spring Boot could not detect the dialect, it uses DEFAULT
.
Spring Boot can only auto-configure dialects supported by the open source version of jOOQ. |
Customizing jOOQ
More advanced customizations can be achieved by defining your own DefaultConfigurationCustomizer
bean that will be invoked prior to creating the org.jooq.Configuration
@Bean
.
This takes precedence to anything that is applied by the auto-configuration.
You can also create your own org.jooq.Configuration
@Bean
if you want to take complete control of the jOOQ configuration.
9.1.8. Using R2DBC
The Reactive Relational Database Connectivity (R2DBC) project brings reactive programming APIs to relational databases.
R2DBC’s io.r2dbc.spi.Connection
provides a standard method of working with non-blocking database connections.
Connections are provided by using a ConnectionFactory
, similar to a DataSource
with jdbc.
ConnectionFactory
configuration is controlled by external configuration properties in spring.r2dbc.*
.
For example, you might declare the following section in application.properties
:
spring.r2dbc.url=r2dbc:postgresql://localhost/test
spring.r2dbc.username=dbuser
spring.r2dbc.password=dbpass
spring:
r2dbc:
url: "r2dbc:postgresql://localhost/test"
username: "dbuser"
password: "dbpass"
You do not need to specify a driver class name, since Spring Boot obtains the driver from R2DBC’s Connection Factory discovery. |
At least the url should be provided.
Information specified in the URL takes precedence over individual properties, that is name , username , password and pooling options.
|
The “How-to” section includes a section on how to initialize a database. |
To customize the connections created by a ConnectionFactory
, that is, set specific parameters that you do not want (or cannot) configure in your central database configuration, you can use a ConnectionFactoryOptionsBuilderCustomizer
@Bean
.
The following example shows how to manually override the database port while the rest of the options are taken from the application configuration:
@Configuration(proxyBeanMethods = false)
public class MyR2dbcConfiguration {
@Bean
public ConnectionFactoryOptionsBuilderCustomizer connectionFactoryPortCustomizer() {
return (builder) -> builder.option(ConnectionFactoryOptions.PORT, 5432);
}
}
@Configuration(proxyBeanMethods = false)
class MyR2dbcConfiguration {
@Bean
fun connectionFactoryPortCustomizer(): ConnectionFactoryOptionsBuilderCustomizer {
return ConnectionFactoryOptionsBuilderCustomizer { builder ->
builder.option(ConnectionFactoryOptions.PORT, 5432)
}
}
}
The following examples show how to set some PostgreSQL connection options:
@Configuration(proxyBeanMethods = false)
public class MyPostgresR2dbcConfiguration {
@Bean
public ConnectionFactoryOptionsBuilderCustomizer postgresCustomizer() {
Map<String, String> options = new HashMap<>();
options.put("lock_timeout", "30s");
options.put("statement_timeout", "60s");
return (builder) -> builder.option(PostgresqlConnectionFactoryProvider.OPTIONS, options);
}
}
@Configuration(proxyBeanMethods = false)
class MyPostgresR2dbcConfiguration {
@Bean
fun postgresCustomizer(): ConnectionFactoryOptionsBuilderCustomizer {
val options: MutableMap<String, String> = HashMap()
options["lock_timeout"] = "30s"
options["statement_timeout"] = "60s"
return ConnectionFactoryOptionsBuilderCustomizer { builder ->
builder.option(PostgresqlConnectionFactoryProvider.OPTIONS, options)
}
}
}
When a ConnectionFactory
bean is available, the regular JDBC DataSource
auto-configuration backs off.
If you want to retain the JDBC DataSource
auto-configuration, and are comfortable with the risk of using the blocking JDBC API in a reactive application, add @Import(DataSourceAutoConfiguration.class)
on a @Configuration
class in your application to re-enable it.
Embedded Database Support
Similarly to the JDBC support, Spring Boot can automatically configure an embedded database for reactive usage. You need not provide any connection URLs. You need only include a build dependency to the embedded database that you want to use, as shown in the following example:
<dependency>
<groupId>io.r2dbc</groupId>
<artifactId>r2dbc-h2</artifactId>
<scope>runtime</scope>
</dependency>
If you are using this feature in your tests, you may notice that the same database is reused by your whole test suite regardless of the number of application contexts that you use.
If you want to make sure that each context has a separate embedded database, you should set |
Using DatabaseClient
A DatabaseClient
bean is auto-configured, and you can @Autowire
it directly into your own beans, as shown in the following example:
@Component
public class MyBean {
private final DatabaseClient databaseClient;
public MyBean(DatabaseClient databaseClient) {
this.databaseClient = databaseClient;
}
}
@Component
class MyBean(private val databaseClient: DatabaseClient) {
}
Spring Data R2DBC Repositories
Spring Data R2DBC repositories are interfaces that you can define to access data.
Queries are created automatically from your method names.
For example, a CityRepository
interface might declare a findAllByState(String state)
method to find all the cities in a given state.
For more complex queries, you can annotate your method with Spring Data’s Query
annotation.
Spring Data repositories usually extend from the Repository
or CrudRepository
interfaces.
If you use auto-configuration, the auto-configuration packages are searched for repositories.
The following example shows a typical Spring Data repository interface definition:
public interface CityRepository extends Repository<City, Long> {
Mono<City> findByNameAndStateAllIgnoringCase(String name, String state);
}
interface CityRepository : Repository<City?, Long?> {
fun findByNameAndStateAllIgnoringCase(name: String?, state: String?): Mono<City?>?
}
We have barely scratched the surface of Spring Data R2DBC. For complete details, see the Spring Data R2DBC reference documentation. |
9.2. Working with NoSQL Technologies
Spring Data provides additional projects that help you access a variety of NoSQL technologies, including:
Of these, Spring Boot provides auto-configuration for Cassandra, Couchbase, Elasticsearch, LDAP, MongoDB, Neo4J and Redis. Additionally, Spring Boot for Apache Geode provides auto-configuration for Apache Geode. You can make use of the other projects, but you must configure them yourself. See the appropriate reference documentation at spring.io/projects/spring-data.
Spring Boot also provides auto-configuration for the InfluxDB client but it is deprecated in favor of the new InfluxDB Java client that provides its own Spring Boot integration.
9.2.1. Redis
Redis is a cache, message broker, and richly-featured key-value store. Spring Boot offers basic auto-configuration for the Lettuce and Jedis client libraries and the abstractions on top of them provided by Spring Data Redis.
There is a spring-boot-starter-data-redis
“Starter” for collecting the dependencies in a convenient way.
By default, it uses Lettuce.
That starter handles both traditional and reactive applications.
We also provide a spring-boot-starter-data-redis-reactive “Starter” for consistency with the other stores with reactive support.
|
Connecting to Redis
You can inject an auto-configured RedisConnectionFactory
, StringRedisTemplate
, or vanilla RedisTemplate
instance as you would any other Spring Bean.
The following listing shows an example of such a bean:
@Component
public class MyBean {
private final StringRedisTemplate template;
public MyBean(StringRedisTemplate template) {
this.template = template;
}
}
@Component
class MyBean(private val template: StringRedisTemplate) {
}
By default, the instance tries to connect to a Redis server at localhost:6379
.
You can specify custom connection details using spring.data.redis.*
properties, as shown in the following example:
spring.data.redis.host=localhost
spring.data.redis.port=6379
spring.data.redis.database=0
spring.data.redis.username=user
spring.data.redis.password=secret
spring:
data:
redis:
host: "localhost"
port: 6379
database: 0
username: "user"
password: "secret"
You can also register an arbitrary number of beans that implement LettuceClientConfigurationBuilderCustomizer for more advanced customizations.
ClientResources can also be customized using ClientResourcesBuilderCustomizer .
If you use Jedis, JedisClientConfigurationBuilderCustomizer is also available.
Alternatively, you can register a bean of type RedisStandaloneConfiguration , RedisSentinelConfiguration , or RedisClusterConfiguration to take full control over the configuration.
|
If you add your own @Bean
of any of the auto-configured types, it replaces the default (except in the case of RedisTemplate
, when the exclusion is based on the bean name, redisTemplate
, not its type).
By default, a pooled connection factory is auto-configured if commons-pool2
is on the classpath.
The auto-configured RedisConnectionFactory
can be configured to use SSL for communication with the server by setting the properties as shown in this example:
spring.data.redis.ssl.enabled=true
spring:
data:
redis:
ssl:
enabled: true
Custom SSL trust material can be configured in an SSL bundle and applied to the RedisConnectionFactory
as shown in this example:
spring.data.redis.ssl.bundle=example
spring:
data:
redis:
ssl:
bundle: "example"
9.2.2. MongoDB
MongoDB is an open-source NoSQL document database that uses a JSON-like schema instead of traditional table-based relational data.
Spring Boot offers several conveniences for working with MongoDB, including the spring-boot-starter-data-mongodb
and spring-boot-starter-data-mongodb-reactive
“Starters”.
Connecting to a MongoDB Database
To access MongoDB databases, you can inject an auto-configured org.springframework.data.mongodb.MongoDatabaseFactory
.
By default, the instance tries to connect to a MongoDB server at mongodb://localhost/test
.
The following example shows how to connect to a MongoDB database:
@Component
public class MyBean {
private final MongoDatabaseFactory mongo;
public MyBean(MongoDatabaseFactory mongo) {
this.mongo = mongo;
}
}
@Component
class MyBean(private val mongo: MongoDatabaseFactory) {
}
If you have defined your own MongoClient
, it will be used to auto-configure a suitable MongoDatabaseFactory
.
The auto-configured MongoClient
is created using a MongoClientSettings
bean.
If you have defined your own MongoClientSettings
, it will be used without modification and the spring.data.mongodb
properties will be ignored.
Otherwise a MongoClientSettings
will be auto-configured and will have the spring.data.mongodb
properties applied to it.
In either case, you can declare one or more MongoClientSettingsBuilderCustomizer
beans to fine-tune the MongoClientSettings
configuration.
Each will be called in order with the MongoClientSettings.Builder
that is used to build the MongoClientSettings
.
You can set the spring.data.mongodb.uri
property to change the URL and configure additional settings such as the replica set, as shown in the following example:
spring.data.mongodb.uri=mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test
spring:
data:
mongodb:
uri: "mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test"
Alternatively, you can specify connection details using discrete properties.
For example, you might declare the following settings in your application.properties
:
spring.data.mongodb.host=mongoserver1.example.com
spring.data.mongodb.port=27017
spring.data.mongodb.additional-hosts[0]=mongoserver2.example.com:23456
spring.data.mongodb.database=test
spring.data.mongodb.username=user
spring.data.mongodb.password=secret
spring:
data:
mongodb:
host: "mongoserver1.example.com"
port: 27017
additional-hosts:
- "mongoserver2.example.com:23456"
database: "test"
username: "user"
password: "secret"
The auto-configured MongoClient
can be configured to use SSL for communication with the server by setting the properties as shown in this example:
spring.data.mongodb.uri=mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test
spring.data.mongodb.ssl.enabled=true
spring:
data:
mongodb:
uri: "mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test"
ssl:
enabled: true
Custom SSL trust material can be configured in an SSL bundle and applied to the MongoClient
as shown in this example:
spring.data.mongodb.uri=mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test
spring.data.mongodb.ssl.bundle=example
spring:
data:
mongodb:
uri: "mongodb://user:[email protected]:27017,mongoserver2.example.com:23456/test"
ssl:
bundle: "example"
If You can also specify the port as part of the host address by using the |
If you do not use Spring Data MongoDB, you can inject a MongoClient bean instead of using MongoDatabaseFactory .
If you want to take complete control of establishing the MongoDB connection, you can also declare your own MongoDatabaseFactory or MongoClient bean.
|
If you are using the reactive driver, Netty is required for SSL. The auto-configuration configures this factory automatically if Netty is available and the factory to use has not been customized already. |
MongoTemplate
Spring Data MongoDB provides a MongoTemplate
class that is very similar in its design to Spring’s JdbcTemplate
.
As with JdbcTemplate
, Spring Boot auto-configures a bean for you to inject the template, as follows:
@Component
public class MyBean {
private final MongoTemplate mongoTemplate;
public MyBean(MongoTemplate mongoTemplate) {
this.mongoTemplate = mongoTemplate;
}
}
@Component
class MyBean(private val mongoTemplate: MongoTemplate) {
}
See the MongoOperations
Javadoc for complete details.
Spring Data MongoDB Repositories
Spring Data includes repository support for MongoDB. As with the JPA repositories discussed earlier, the basic principle is that queries are constructed automatically, based on method names.
In fact, both Spring Data JPA and Spring Data MongoDB share the same common infrastructure.
You could take the JPA example from earlier and, assuming that City
is now a MongoDB data class rather than a JPA @Entity
, it works in the same way, as shown in the following example:
public interface CityRepository extends Repository<City, Long> {
Page<City> findAll(Pageable pageable);
City findByNameAndStateAllIgnoringCase(String name, String state);
}
interface CityRepository :
Repository<City?, Long?> {
fun findAll(pageable: Pageable?): Page<City?>?
fun findByNameAndStateAllIgnoringCase(name: String?, state: String?): City?
}
Repositories and documents are found through scanning.
By default, the auto-configuration packages are scanned.
You can customize the locations to look for repositories and documents by using @EnableMongoRepositories
and @EntityScan
respectively.
For complete details of Spring Data MongoDB, including its rich object mapping technologies, see its reference documentation. |
9.2.3. Neo4j
Neo4j is an open-source NoSQL graph database that uses a rich data model of nodes connected by first class relationships, which is better suited for connected big data than traditional RDBMS approaches.
Spring Boot offers several conveniences for working with Neo4j, including the spring-boot-starter-data-neo4j
“Starter”.
Connecting to a Neo4j Database
To access a Neo4j server, you can inject an auto-configured org.neo4j.driver.Driver
.
By default, the instance tries to connect to a Neo4j server at localhost:7687
using the Bolt protocol.
The following example shows how to inject a Neo4j Driver
that gives you access, amongst other things, to a Session
:
@Component
public class MyBean {
private final Driver driver;
public MyBean(Driver driver) {
this.driver = driver;
}
}
@Component
class MyBean(private val driver: Driver) {
}
You can configure various aspects of the driver using spring.neo4j.*
properties.
The following example shows how to configure the uri and credentials to use:
spring.neo4j.uri=bolt://my-server:7687
spring.neo4j.authentication.username=neo4j
spring.neo4j.authentication.password=secret
spring:
neo4j:
uri: "bolt://my-server:7687"
authentication:
username: "neo4j"
password: "secret"
The auto-configured Driver
is created using ConfigBuilder
.
To fine-tune its configuration, declare one or more ConfigBuilderCustomizer
beans.
Each will be called in order with the ConfigBuilder
that is used to build the Driver
.
Spring Data Neo4j Repositories
Spring Data includes repository support for Neo4j. For complete details of Spring Data Neo4j, see the reference documentation.
Spring Data Neo4j shares the common infrastructure with Spring Data JPA as many other Spring Data modules do.
You could take the JPA example from earlier and define City
as Spring Data Neo4j @Node
rather than JPA @Entity
and the repository abstraction works in the same way, as shown in the following example:
public interface CityRepository extends Neo4jRepository<City, Long> {
Optional<City> findOneByNameAndState(String name, String state);
}
interface CityRepository : Neo4jRepository<City?, Long?> {
fun findOneByNameAndState(name: String?, state: String?): Optional<City?>?
}
The spring-boot-starter-data-neo4j
“Starter” enables the repository support as well as transaction management.
Spring Boot supports both classic and reactive Neo4j repositories, using the Neo4jTemplate
or ReactiveNeo4jTemplate
beans.
When Project Reactor is available on the classpath, the reactive style is also auto-configured.
Repositories and entities are found through scanning.
By default, the auto-configuration packages are scanned.
You can customize the locations to look for repositories and entities by using @EnableNeo4jRepositories
and @EntityScan
respectively.
In an application using the reactive style, a Java
Kotlin
|
9.2.4. Elasticsearch
Elasticsearch is an open source, distributed, RESTful search and analytics engine. Spring Boot offers basic auto-configuration for Elasticsearch clients.
Spring Boot supports several clients:
-
The official low-level REST client
-
The official Java API client
-
The
ReactiveElasticsearchClient
provided by Spring Data Elasticsearch
Spring Boot provides a dedicated “Starter”, spring-boot-starter-data-elasticsearch
.
Connecting to Elasticsearch Using REST clients
Elasticsearch ships two different REST clients that you can use to query a cluster: the low-level client from the org.elasticsearch.client:elasticsearch-rest-client
module and the Java API client from the co.elastic.clients:elasticsearch-java
module.
Additionally, Spring Boot provides support for a reactive client from the org.springframework.data:spring-data-elasticsearch
module.
By default, the clients will target localhost:9200
.
You can use spring.elasticsearch.*
properties to further tune how the clients are configured, as shown in the following example:
spring.elasticsearch.uris=https://search.example.com:9200
spring.elasticsearch.socket-timeout=10s
spring.elasticsearch.username=user
spring.elasticsearch.password=secret
spring:
elasticsearch:
uris: "https://search.example.com:9200"
socket-timeout: "10s"
username: "user"
password: "secret"
Connecting to Elasticsearch Using RestClient
If you have elasticsearch-rest-client
on the classpath, Spring Boot will auto-configure and register a RestClient
bean.
In addition to the properties described previously, to fine-tune the RestClient
you can register an arbitrary number of beans that implement RestClientBuilderCustomizer
for more advanced customizations.
To take full control over the clients' configuration, define a RestClientBuilder
bean.
Additionally, if elasticsearch-rest-client-sniffer
is on the classpath, a Sniffer
is auto-configured to automatically discover nodes from a running Elasticsearch cluster and set them on the RestClient
bean.
You can further tune how Sniffer
is configured, as shown in the following example:
spring.elasticsearch.restclient.sniffer.interval=10m
spring.elasticsearch.restclient.sniffer.delay-after-failure=30s
spring:
elasticsearch:
restclient:
sniffer:
interval: "10m"
delay-after-failure: "30s"
Connecting to Elasticsearch Using ElasticsearchClient
If you have co.elastic.clients:elasticsearch-java
on the classpath, Spring Boot will auto-configure and register an ElasticsearchClient
bean.
The ElasticsearchClient
uses a transport that depends upon the previously described RestClient
.
Therefore, the properties described previously can be used to configure the ElasticsearchClient
.
Furthermore, you can define a RestClientOptions
bean to take further control of the behavior of the transport.
Connecting to Elasticsearch using ReactiveElasticsearchClient
Spring Data Elasticsearch ships ReactiveElasticsearchClient
for querying Elasticsearch instances in a reactive fashion.
If you have Spring Data Elasticsearch and Reactor on the classpath, Spring Boot will auto-configure and register a ReactiveElasticsearchClient
.
The ReactiveElasticsearchclient
uses a transport that depends upon the previously described RestClient
.
Therefore, the properties described previously can be used to configure the ReactiveElasticsearchClient
.
Furthermore, you can define a RestClientOptions
bean to take further control of the behavior of the transport.
Connecting to Elasticsearch by Using Spring Data
To connect to Elasticsearch, an ElasticsearchClient
bean must be defined,
auto-configured by Spring Boot or manually provided by the application (see previous sections).
With this configuration in place, an
ElasticsearchTemplate
can be injected like any other Spring bean,
as shown in the following example:
@Component
public class MyBean {
private final ElasticsearchTemplate template;
public MyBean(ElasticsearchTemplate template) {
this.template = template;
}
}
@Component
class MyBean(private val template: org.springframework.data.elasticsearch.client.elc.ElasticsearchTemplate ) {
}
In the presence of spring-data-elasticsearch
and Reactor, Spring Boot can also auto-configure a ReactiveElasticsearchClient and a ReactiveElasticsearchTemplate
as beans.
They are the reactive equivalent of the other REST clients.
Spring Data Elasticsearch Repositories
Spring Data includes repository support for Elasticsearch. As with the JPA repositories discussed earlier, the basic principle is that queries are constructed for you automatically based on method names.
In fact, both Spring Data JPA and Spring Data Elasticsearch share the same common infrastructure.
You could take the JPA example from earlier and, assuming that City
is now an Elasticsearch @Document
class rather than a JPA @Entity
, it works in the same way.
Repositories and documents are found through scanning.
By default, the auto-configuration packages are scanned.
You can customize the locations to look for repositories and documents by using @EnableElasticsearchRepositories
and @EntityScan
respectively.
For complete details of Spring Data Elasticsearch, see the reference documentation. |
Spring Boot supports both classic and reactive Elasticsearch repositories, using the ElasticsearchRestTemplate
or ReactiveElasticsearchTemplate
beans.
Most likely those beans are auto-configured by Spring Boot given the required dependencies are present.
If you wish to use your own template for backing the Elasticsearch repositories, you can add your own ElasticsearchRestTemplate
or ElasticsearchOperations
@Bean
, as long as it is named "elasticsearchTemplate"
.
Same applies to ReactiveElasticsearchTemplate
and ReactiveElasticsearchOperations
, with the bean name "reactiveElasticsearchTemplate"
.
You can choose to disable the repositories support with the following property:
spring.data.elasticsearch.repositories.enabled=false
spring:
data:
elasticsearch:
repositories:
enabled: false
9.2.5. Cassandra
Cassandra is an open source, distributed database management system designed to handle large amounts of data across many commodity servers.
Spring Boot offers auto-configuration for Cassandra and the abstractions on top of it provided by Spring Data Cassandra.
There is a spring-boot-starter-data-cassandra
“Starter” for collecting the dependencies in a convenient way.
Connecting to Cassandra
You can inject an auto-configured CassandraTemplate
or a Cassandra CqlSession
instance as you would with any other Spring Bean.
The spring.cassandra.*
properties can be used to customize the connection.
Generally, you provide keyspace-name
and contact-points
as well the local datacenter name, as shown in the following example:
spring.cassandra.keyspace-name=mykeyspace
spring.cassandra.contact-points=cassandrahost1:9042,cassandrahost2:9042
spring.cassandra.local-datacenter=datacenter1
spring:
cassandra:
keyspace-name: "mykeyspace"
contact-points: "cassandrahost1:9042,cassandrahost2:9042"
local-datacenter: "datacenter1"
If the port is the same for all your contact points you can use a shortcut and only specify the host names, as shown in the following example:
spring.cassandra.keyspace-name=mykeyspace
spring.cassandra.contact-points=cassandrahost1,cassandrahost2
spring.cassandra.local-datacenter=datacenter1
spring:
cassandra:
keyspace-name: "mykeyspace"
contact-points: "cassandrahost1,cassandrahost2"
local-datacenter: "datacenter1"
Those two examples are identical as the port default to 9042 .
If you need to configure the port, use spring.cassandra.port .
|
The auto-configured CqlSession
can be configured to use SSL for communication with the server by setting the properties as shown in this example:
spring.cassandra.keyspace-name=mykeyspace
spring.cassandra.contact-points=cassandrahost1,cassandrahost2
spring.cassandra.local-datacenter=datacenter1
spring.cassandra.ssl.enabled=true
spring:
cassandra:
keyspace-name: "mykeyspace"
contact-points: "cassandrahost1,cassandrahost2"
local-datacenter: "datacenter1"
ssl:
enabled: true
Custom SSL trust material can be configured in an SSL bundle and applied to the CqlSession
as shown in this example:
spring.cassandra.keyspace-name=mykeyspace
spring.cassandra.contact-points=cassandrahost1,cassandrahost2
spring.cassandra.local-datacenter=datacenter1
spring.cassandra.ssl.bundle=example
spring:
cassandra:
keyspace-name: "mykeyspace"
contact-points: "cassandrahost1,cassandrahost2"
local-datacenter: "datacenter1"
ssl:
bundle: "example"
The Cassandra driver has its own configuration infrastructure that loads an Spring Boot does not look for such a file by default but can load one using For more advanced driver customizations, you can register an arbitrary number of beans that implement |
If you use CqlSessionBuilder to create multiple CqlSession beans, keep in mind the builder is mutable so make sure to inject a fresh copy for each session.
|
The following code listing shows how to inject a Cassandra bean:
@Component
public class MyBean {
private final CassandraTemplate template;
public MyBean(CassandraTemplate template) {
this.template = template;
}
}
@Component
class MyBean(private val template: CassandraTemplate) {
}
If you add your own @Bean
of type CassandraTemplate
, it replaces the default.
Spring Data Cassandra Repositories
Spring Data includes basic repository support for Cassandra.
Currently, this is more limited than the JPA repositories discussed earlier and needs @Query
annotated finder methods.
Repositories and entities are found through scanning.
By default, the auto-configuration packages are scanned.
You can customize the locations to look for repositories and entities by using @EnableCassandraRepositories
and @EntityScan
respectively.
For complete details of Spring Data Cassandra, see the reference documentation. |
9.2.6. Couchbase
Couchbase is an open-source, distributed, multi-model NoSQL document-oriented database that is optimized for interactive applications.
Spring Boot offers auto-configuration for Couchbase and the abstractions on top of it provided by Spring Data Couchbase.
There are spring-boot-starter-data-couchbase
and spring-boot-starter-data-couchbase-reactive
“Starters” for collecting the dependencies in a convenient way.
Connecting to Couchbase
You can get a Cluster
by adding the Couchbase SDK and some configuration.
The spring.couchbase.*
properties can be used to customize the connection.
Generally, you provide the connection string, username, and password, as shown in the following example:
spring.couchbase.connection-string=couchbase://192.168.1.123
spring.couchbase.username=user
spring.couchbase.password=secret
spring:
couchbase:
connection-string: "couchbase://192.168.1.123"
username: "user"
password: "secret"
It is also possible to customize some of the ClusterEnvironment
settings.
For instance, the following configuration changes the timeout to open a new Bucket
and enables SSL support with a reference to a configured SSL bundle:
spring.couchbase.env.timeouts.connect=3s
spring.couchbase.env.ssl.bundle=example
spring:
couchbase:
env:
timeouts:
connect: "3s"
ssl:
bundle: "example"
Check the spring.couchbase.env.* properties for more details.
To take more control, one or more ClusterEnvironmentBuilderCustomizer beans can be used.
|
Spring Data Couchbase Repositories
Spring Data includes repository support for Couchbase.
Repositories and documents are found through scanning.
By default, the auto-configuration packages are scanned.
You can customize the locations to look for repositories and documents by using @EnableCouchbaseRepositories
and @EntityScan
respectively.
For complete details of Spring Data Couchbase, see the reference documentation.
You can inject an auto-configured CouchbaseTemplate
instance as you would with any other Spring Bean, provided a CouchbaseClientFactory
bean is available.
This happens when a Cluster
is available, as described above, and a bucket name has been specified:
spring.data.couchbase.bucket-name=my-bucket
spring:
data:
couchbase:
bucket-name: "my-bucket"
The following examples shows how to inject a CouchbaseTemplate
bean:
@Component
public class MyBean {
private final CouchbaseTemplate template;
public MyBean(CouchbaseTemplate template) {
this.template = template;
}
}
@Component
class MyBean(private val template: CouchbaseTemplate) {
}
There are a few beans that you can define in your own configuration to override those provided by the auto-configuration:
-
A
CouchbaseMappingContext
@Bean
with a name ofcouchbaseMappingContext
. -
A
CustomConversions
@Bean
with a name ofcouchbaseCustomConversions
. -
A
CouchbaseTemplate
@Bean
with a name ofcouchbaseTemplate
.
To avoid hard-coding those names in your own config, you can reuse BeanNames
provided by Spring Data Couchbase.
For instance, you can customize the converters to use, as follows:
@Configuration(proxyBeanMethods = false)
public class MyCouchbaseConfiguration {
@Bean(BeanNames.COUCHBASE_CUSTOM_CONVERSIONS)
public CouchbaseCustomConversions myCustomConversions() {
return new CouchbaseCustomConversions(Arrays.asList(new MyConverter()));
}
}
@Configuration(proxyBeanMethods = false)
class MyCouchbaseConfiguration {
@Bean(BeanNames.COUCHBASE_CUSTOM_CONVERSIONS)
fun myCustomConversions(): CouchbaseCustomConversions {
return CouchbaseCustomConversions(Arrays.asList(MyConverter()))
}
}
9.2.7. LDAP
LDAP (Lightweight Directory Access Protocol) is an open, vendor-neutral, industry standard application protocol for accessing and maintaining distributed directory information services over an IP network. Spring Boot offers auto-configuration for any compliant LDAP server as well as support for the embedded in-memory LDAP server from UnboundID.
LDAP abstractions are provided by Spring Data LDAP.
There is a spring-boot-starter-data-ldap
“Starter” for collecting the dependencies in a convenient way.
Connecting to an LDAP Server
To connect to an LDAP server, make sure you declare a dependency on the spring-boot-starter-data-ldap
“Starter” or spring-ldap-core
and then declare the URLs of your server in your application.properties, as shown in the following example:
spring.ldap.urls=ldap://myserver:1235
spring.ldap.username=admin
spring.ldap.password=secret
spring:
ldap:
urls: "ldap://myserver:1235"
username: "admin"
password: "secret"
If you need to customize connection settings, you can use the spring.ldap.base
and spring.ldap.base-environment
properties.
An LdapContextSource
is auto-configured based on these settings.
If a DirContextAuthenticationStrategy
bean is available, it is associated to the auto-configured LdapContextSource
.
If you need to customize it, for instance to use a PooledContextSource
, you can still inject the auto-configured LdapContextSource
.
Make sure to flag your customized ContextSource
as @Primary
so that the auto-configured LdapTemplate
uses it.
Spring Data LDAP Repositories
Spring Data includes repository support for LDAP.
Repositories and documents are found through scanning.
By default, the auto-configuration packages are scanned.
You can customize the locations to look for repositories and documents by using @EnableLdapRepositories
and @EntityScan
respectively.
For complete details of Spring Data LDAP, see the reference documentation.
You can also inject an auto-configured LdapTemplate
instance as you would with any other Spring Bean, as shown in the following example:
@Component
public class MyBean {
private final LdapTemplate template;
public MyBean(LdapTemplate template) {
this.template = template;
}
}
@Component
class MyBean(private val template: LdapTemplate) {
}
Embedded In-memory LDAP Server
For testing purposes, Spring Boot supports auto-configuration of an in-memory LDAP server from UnboundID.
To configure the server, add a dependency to com.unboundid:unboundid-ldapsdk
and declare a spring.ldap.embedded.base-dn
property, as follows:
spring.ldap.embedded.base-dn=dc=spring,dc=io
spring:
ldap:
embedded:
base-dn: "dc=spring,dc=io"
It is possible to define multiple base-dn values, however, since distinguished names usually contain commas, they must be defined using the correct notation. In yaml files, you can use the yaml list notation. In properties files, you must include the index as part of the property name: Properties
Yaml
|
By default, the server starts on a random port and triggers the regular LDAP support.
There is no need to specify a spring.ldap.urls
property.
If there is a schema.ldif
file on your classpath, it is used to initialize the server.
If you want to load the initialization script from a different resource, you can also use the spring.ldap.embedded.ldif
property.
By default, a standard schema is used to validate LDIF
files.
You can turn off validation altogether by setting the spring.ldap.embedded.validation.enabled
property.
If you have custom attributes, you can use spring.ldap.embedded.validation.schema
to define your custom attribute types or object classes.
9.2.8. InfluxDB
Auto-configuration for InfluxDB is deprecated and scheduled for removal in Spring Boot 3.4 in favor of the new InfluxDB Java client that provides its own Spring Boot integration. |
InfluxDB is an open-source time series database optimized for fast, high-availability storage and retrieval of time series data in fields such as operations monitoring, application metrics, Internet-of-Things sensor data, and real-time analytics.
Connecting to InfluxDB
Spring Boot auto-configures an InfluxDB
instance, provided the influxdb-java
client is on the classpath and the URL of the database is set using spring.influx.url
.
If the connection to InfluxDB requires a user and password, you can set the spring.influx.user
and spring.influx.password
properties accordingly.
InfluxDB relies on OkHttp.
If you need to tune the http client InfluxDB
uses behind the scenes, you can register an InfluxDbOkHttpClientBuilderProvider
bean.
If you need more control over the configuration, consider registering an InfluxDbCustomizer
bean.
9.3. What to Read Next
You should now have a feeling for how to use Spring Boot with various data technologies. From here, you can read about Spring Boot’s support for various messaging technologies and how to enable them in your application.
10. Messaging
The Spring Framework provides extensive support for integrating with messaging systems, from simplified use of the JMS API using JmsTemplate
to a complete infrastructure to receive messages asynchronously.
Spring AMQP provides a similar feature set for the Advanced Message Queuing Protocol.
Spring Boot also provides auto-configuration options for RabbitTemplate
and RabbitMQ.
Spring WebSocket natively includes support for STOMP messaging, and Spring Boot has support for that through starters and a small amount of auto-configuration.
Spring Boot also has support for Apache Kafka and Apache Pulsar.
10.1. JMS
The jakarta.jms.ConnectionFactory
interface provides a standard method of creating a jakarta.jms.Connection
for interacting with a JMS broker.
Although Spring needs a ConnectionFactory
to work with JMS, you generally need not use it directly yourself and can instead rely on higher level messaging abstractions.
(See the relevant section of the Spring Framework reference documentation for details.)
Spring Boot also auto-configures the necessary infrastructure to send and receive messages.
10.1.1. ActiveMQ "Classic" Support
When ActiveMQ "Classic" is available on the classpath, Spring Boot can configure a ConnectionFactory
.
If you use spring-boot-starter-activemq , the necessary dependencies to connect to an ActiveMQ "Classic" instance are provided, as is the Spring infrastructure to integrate with JMS.
|
ActiveMQ "Classic" configuration is controlled by external configuration properties in spring.activemq.*
.
By default, ActiveMQ "Classic" is auto-configured to use the TCP transport, connecting by default to tcp://localhost:61616
. The following example shows how to change the default broker URL:
spring.activemq.broker-url=tcp://192.168.1.210:9876
spring.activemq.user=admin
spring.activemq.password=secret
spring:
activemq:
broker-url: "tcp://192.168.1.210:9876"
user: "admin"
password: "secret"
By default, a CachingConnectionFactory
wraps the native ConnectionFactory
with sensible settings that you can control by external configuration properties in spring.jms.*
:
spring.jms.cache.session-cache-size=5
spring:
jms:
cache:
session-cache-size: 5
If you’d rather use native pooling, you can do so by adding a dependency to org.messaginghub:pooled-jms
and configuring the JmsPoolConnectionFactory
accordingly, as shown in the following example:
spring.activemq.pool.enabled=true
spring.activemq.pool.max-connections=50
spring:
activemq:
pool:
enabled: true
max-connections: 50
See ActiveMQProperties for more of the supported options.
You can also register an arbitrary number of beans that implement ActiveMQConnectionFactoryCustomizer for more advanced customizations.
|
By default, ActiveMQ "Classic" creates a destination if it does not yet exist so that destinations are resolved against their provided names.
10.1.2. ActiveMQ Artemis Support
Spring Boot can auto-configure a ConnectionFactory
when it detects that ActiveMQ Artemis is available on the classpath.
If the broker is present, an embedded broker is automatically started and configured (unless the mode property has been explicitly set).
The supported modes are embedded
(to make explicit that an embedded broker is required and that an error should occur if the broker is not available on the classpath) and native
(to connect to a broker using the netty
transport protocol).
When the latter is configured, Spring Boot configures a ConnectionFactory
that connects to a broker running on the local machine with the default settings.
If you use spring-boot-starter-artemis , the necessary dependencies to connect to an existing ActiveMQ Artemis instance are provided, as well as the Spring infrastructure to integrate with JMS.
Adding org.apache.activemq:artemis-jakarta-server to your application lets you use embedded mode.
|
ActiveMQ Artemis configuration is controlled by external configuration properties in spring.artemis.*
.
For example, you might declare the following section in application.properties
:
spring.artemis.mode=native
spring.artemis.broker-url=tcp://192.168.1.210:9876
spring.artemis.user=admin
spring.artemis.password=secret
spring:
artemis:
mode: native
broker-url: "tcp://192.168.1.210:9876"
user: "admin"
password: "secret"
When embedding the broker, you can choose if you want to enable persistence and list the destinations that should be made available.
These can be specified as a comma-separated list to create them with the default options, or you can define bean(s) of type org.apache.activemq.artemis.jms.server.config.JMSQueueConfiguration
or org.apache.activemq.artemis.jms.server.config.TopicConfiguration
, for advanced queue and topic configurations, respectively.
By default, a CachingConnectionFactory
wraps the native ConnectionFactory
with sensible settings that you can control by external configuration properties in spring.jms.*
:
spring.jms.cache.session-cache-size=5
spring:
jms:
cache:
session-cache-size: 5
If you’d rather use native pooling, you can do so by adding a dependency on org.messaginghub:pooled-jms
and configuring the JmsPoolConnectionFactory
accordingly, as shown in the following example:
spring.artemis.pool.enabled=true
spring.artemis.pool.max-connections=50
spring:
artemis:
pool:
enabled: true
max-connections: 50
See ArtemisProperties
for more supported options.
No JNDI lookup is involved, and destinations are resolved against their names, using either the name
attribute in the ActiveMQ Artemis configuration or the names provided through configuration.
10.1.3. Using a JNDI ConnectionFactory
If you are running your application in an application server, Spring Boot tries to locate a JMS ConnectionFactory
by using JNDI.
By default, the java:/JmsXA
and java:/XAConnectionFactory
location are checked.
You can use the spring.jms.jndi-name
property if you need to specify an alternative location, as shown in the following example:
spring.jms.jndi-name=java:/MyConnectionFactory
spring:
jms:
jndi-name: "java:/MyConnectionFactory"
10.1.4. Sending a Message
Spring’s JmsTemplate
is auto-configured, and you can autowire it directly into your own beans, as shown in the following example:
@Component
public class MyBean {
private final JmsTemplate jmsTemplate;
public MyBean(JmsTemplate jmsTemplate) {
this.jmsTemplate = jmsTemplate;
}
}
@Component
class MyBean(private val jmsTemplate: JmsTemplate) {
}
JmsMessagingTemplate can be injected in a similar manner.
If a DestinationResolver or a MessageConverter bean is defined, it is associated automatically to the auto-configured JmsTemplate .
|
10.1.5. Receiving a Message
When the JMS infrastructure is present, any bean can be annotated with @JmsListener
to create a listener endpoint.
If no JmsListenerContainerFactory
has been defined, a default one is configured automatically.
If a DestinationResolver
, a MessageConverter
, or a jakarta.jms.ExceptionListener
beans are defined, they are associated automatically with the default factory.
By default, the default factory is transactional.
If you run in an infrastructure where a JtaTransactionManager
is present, it is associated to the listener container by default.
If not, the sessionTransacted
flag is enabled.
In that latter scenario, you can associate your local data store transaction to the processing of an incoming message by adding @Transactional
on your listener method (or a delegate thereof).
This ensures that the incoming message is acknowledged, once the local transaction has completed.
This also includes sending response messages that have been performed on the same JMS session.
The following component creates a listener endpoint on the someQueue
destination:
@Component
public class MyBean {
@JmsListener(destination = "someQueue")
public void processMessage(String content) {
// ...
}
}
@Component
class MyBean {
@JmsListener(destination = "someQueue")
fun processMessage(content: String?) {
// ...
}
}
See the Javadoc of @EnableJms for more details.
|
If you need to create more JmsListenerContainerFactory
instances or if you want to override the default, Spring Boot provides a DefaultJmsListenerContainerFactoryConfigurer
that you can use to initialize a DefaultJmsListenerContainerFactory
with the same settings as the one that is auto-configured.
For instance, the following example exposes another factory that uses a specific MessageConverter
:
@Configuration(proxyBeanMethods = false)
public class MyJmsConfiguration {
@Bean
public DefaultJmsListenerContainerFactory myFactory(DefaultJmsListenerContainerFactoryConfigurer configurer) {
DefaultJmsListenerContainerFactory factory = new DefaultJmsListenerContainerFactory();
ConnectionFactory connectionFactory = getCustomConnectionFactory();
configurer.configure(factory, connectionFactory);
factory.setMessageConverter(new MyMessageConverter());
return factory;
}
private ConnectionFactory getCustomConnectionFactory() {
return ...
}
}
@Configuration(proxyBeanMethods = false)
class MyJmsConfiguration {
@Bean
fun myFactory(configurer: DefaultJmsListenerContainerFactoryConfigurer): DefaultJmsListenerContainerFactory {
val factory = DefaultJmsListenerContainerFactory()
val connectionFactory = getCustomConnectionFactory()
configurer.configure(factory, connectionFactory)
factory.setMessageConverter(MyMessageConverter())
return factory
}
fun getCustomConnectionFactory() : ConnectionFactory? {
return ...
}
}
Then you can use the factory in any @JmsListener
-annotated method as follows:
@Component
public class MyBean {
@JmsListener(destination = "someQueue", containerFactory = "myFactory")
public void processMessage(String content) {
// ...
}
}
@Component
class MyBean {
@JmsListener(destination = "someQueue", containerFactory = "myFactory")
fun processMessage(content: String?) {
// ...
}
}
10.2. AMQP
The Advanced Message Queuing Protocol (AMQP) is a platform-neutral, wire-level protocol for message-oriented middleware.
The Spring AMQP project applies core Spring concepts to the development of AMQP-based messaging solutions.
Spring Boot offers several conveniences for working with AMQP through RabbitMQ, including the spring-boot-starter-amqp
“Starter”.
10.2.1. RabbitMQ Support
RabbitMQ is a lightweight, reliable, scalable, and portable message broker based on the AMQP protocol. Spring uses RabbitMQ to communicate through the AMQP protocol.
RabbitMQ configuration is controlled by external configuration properties in spring.rabbitmq.*
.
For example, you might declare the following section in application.properties
:
spring.rabbitmq.host=localhost
spring.rabbitmq.port=5672
spring.rabbitmq.username=admin
spring.rabbitmq.password=secret
spring:
rabbitmq:
host: "localhost"
port: 5672
username: "admin"
password: "secret"
Alternatively, you could configure the same connection using the addresses
attribute:
spring.rabbitmq.addresses=amqp://admin:secret@localhost
spring:
rabbitmq:
addresses: "amqp://admin:secret@localhost"
When specifying addresses that way, the host and port properties are ignored.
If the address uses the amqps protocol, SSL support is enabled automatically.
|
See RabbitProperties
for more of the supported property-based configuration options.
To configure lower-level details of the RabbitMQ ConnectionFactory
that is used by Spring AMQP, define a ConnectionFactoryCustomizer
bean.
If a ConnectionNameStrategy
bean exists in the context, it will be automatically used to name connections created by the auto-configured CachingConnectionFactory
.
To make an application-wide, additive customization to the RabbitTemplate
, use a RabbitTemplateCustomizer
bean.
See Understanding AMQP, the protocol used by RabbitMQ for more details. |
10.2.2. Sending a Message
Spring’s AmqpTemplate
and AmqpAdmin
are auto-configured, and you can autowire them directly into your own beans, as shown in the following example:
@Component
public class MyBean {
private final AmqpAdmin amqpAdmin;
private final AmqpTemplate amqpTemplate;
public MyBean(AmqpAdmin amqpAdmin, AmqpTemplate amqpTemplate) {
this.amqpAdmin = amqpAdmin;
this.amqpTemplate = amqpTemplate;
}
}
@Component
class MyBean(private val amqpAdmin: AmqpAdmin, private val amqpTemplate: AmqpTemplate) {
}
RabbitMessagingTemplate can be injected in a similar manner.
If a MessageConverter bean is defined, it is associated automatically to the auto-configured AmqpTemplate .
|
If necessary, any org.springframework.amqp.core.Queue
that is defined as a bean is automatically used to declare a corresponding queue on the RabbitMQ instance.
To retry operations, you can enable retries on the AmqpTemplate
(for example, in the event that the broker connection is lost):
spring.rabbitmq.template.retry.enabled=true
spring.rabbitmq.template.retry.initial-interval=2s
spring:
rabbitmq:
template:
retry:
enabled: true
initial-interval: "2s"
Retries are disabled by default.
You can also customize the RetryTemplate
programmatically by declaring a RabbitRetryTemplateCustomizer
bean.
If you need to create more RabbitTemplate
instances or if you want to override the default, Spring Boot provides a RabbitTemplateConfigurer
bean that you can use to initialize a RabbitTemplate
with the same settings as the factories used by the auto-configuration.
10.2.3. Sending a Message To A Stream
To send a message to a particular stream, specify the name of the stream, as shown in the following example:
spring.rabbitmq.stream.name=my-stream
spring:
rabbitmq:
stream:
name: "my-stream"
If a MessageConverter
, StreamMessageConverter
, or ProducerCustomizer
bean is defined, it is associated automatically to the auto-configured RabbitStreamTemplate
.
If you need to create more RabbitStreamTemplate
instances or if you want to override the default, Spring Boot provides a RabbitStreamTemplateConfigurer
bean that you can use to initialize a RabbitStreamTemplate
with the same settings as the factories used by the auto-configuration.
10.2.4. Receiving a Message
When the Rabbit infrastructure is present, any bean can be annotated with @RabbitListener
to create a listener endpoint.
If no RabbitListenerContainerFactory
has been defined, a default SimpleRabbitListenerContainerFactory
is automatically configured and you can switch to a direct container using the spring.rabbitmq.listener.type
property.
If a MessageConverter
or a MessageRecoverer
bean is defined, it is automatically associated with the default factory.
The following sample component creates a listener endpoint on the someQueue
queue:
@Component
public class MyBean {
@RabbitListener(queues = "someQueue")
public void processMessage(String content) {
// ...
}
}
@Component
class MyBean {
@RabbitListener(queues = ["someQueue"])
fun processMessage(content: String?) {
// ...
}
}
See the Javadoc of @EnableRabbit for more details.
|
If you need to create more RabbitListenerContainerFactory
instances or if you want to override the default, Spring Boot provides a SimpleRabbitListenerContainerFactoryConfigurer
and a DirectRabbitListenerContainerFactoryConfigurer
that you can use to initialize a SimpleRabbitListenerContainerFactory
and a DirectRabbitListenerContainerFactory
with the same settings as the factories used by the auto-configuration.
It does not matter which container type you chose. Those two beans are exposed by the auto-configuration. |
For instance, the following configuration class exposes another factory that uses a specific MessageConverter
:
@Configuration(proxyBeanMethods = false)
public class MyRabbitConfiguration {
@Bean
public SimpleRabbitListenerContainerFactory myFactory(SimpleRabbitListenerContainerFactoryConfigurer configurer) {
SimpleRabbitListenerContainerFactory factory = new SimpleRabbitListenerContainerFactory();
ConnectionFactory connectionFactory = getCustomConnectionFactory();
configurer.configure(factory, connectionFactory);
factory.setMessageConverter(new MyMessageConverter());
return factory;
}
private ConnectionFactory getCustomConnectionFactory() {
return ...
}
}
@Configuration(proxyBeanMethods = false)
class MyRabbitConfiguration {
@Bean
fun myFactory(configurer: SimpleRabbitListenerContainerFactoryConfigurer): SimpleRabbitListenerContainerFactory {
val factory = SimpleRabbitListenerContainerFactory()
val connectionFactory = getCustomConnectionFactory()
configurer.configure(factory, connectionFactory)
factory.setMessageConverter(MyMessageConverter())
return factory
}
fun getCustomConnectionFactory() : ConnectionFactory? {
return ...
}
}
Then you can use the factory in any @RabbitListener
-annotated method, as follows:
@Component
public class MyBean {
@RabbitListener(queues = "someQueue", containerFactory = "myFactory")
public void processMessage(String content) {
// ...
}
}
@Component
class MyBean {
@RabbitListener(queues = ["someQueue"], containerFactory = "myFactory")
fun processMessage(content: String?) {
// ...
}
}
You can enable retries to handle situations where your listener throws an exception.
By default, RejectAndDontRequeueRecoverer
is used, but you can define a MessageRecoverer
of your own.
When retries are exhausted, the message is rejected and either dropped or routed to a dead-letter exchange if the broker is configured to do so.
By default, retries are disabled.
You can also customize the RetryTemplate
programmatically by declaring a RabbitRetryTemplateCustomizer
bean.
By default, if retries are disabled and the listener throws an exception, the delivery is retried indefinitely.
You can modify this behavior in two ways: Set the defaultRequeueRejected property to false so that zero re-deliveries are attempted or throw an AmqpRejectAndDontRequeueException to signal the message should be rejected.
The latter is the mechanism used when retries are enabled and the maximum number of delivery attempts is reached.
|
10.3. Apache Kafka Support
Apache Kafka is supported by providing auto-configuration of the spring-kafka
project.
Kafka configuration is controlled by external configuration properties in spring.kafka.*
.
For example, you might declare the following section in application.properties
:
spring.kafka.bootstrap-servers=localhost:9092
spring.kafka.consumer.group-id=myGroup
spring:
kafka:
bootstrap-servers: "localhost:9092"
consumer:
group-id: "myGroup"
To create a topic on startup, add a bean of type NewTopic .
If the topic already exists, the bean is ignored.
|
See KafkaProperties
for more supported options.
10.3.1. Sending a Message
Spring’s KafkaTemplate
is auto-configured, and you can autowire it directly in your own beans, as shown in the following example:
@Component
public class MyBean {
private final KafkaTemplate<String, String> kafkaTemplate;
public MyBean(KafkaTemplate<String, String> kafkaTemplate) {
this.kafkaTemplate = kafkaTemplate;
}
}
@Component
class MyBean(private val kafkaTemplate: KafkaTemplate<String, String>) {
}
If the property spring.kafka.producer.transaction-id-prefix is defined, a KafkaTransactionManager is automatically configured.
Also, if a RecordMessageConverter bean is defined, it is automatically associated to the auto-configured KafkaTemplate .
|
10.3.2. Receiving a Message
When the Apache Kafka infrastructure is present, any bean can be annotated with @KafkaListener
to create a listener endpoint.
If no KafkaListenerContainerFactory
has been defined, a default one is automatically configured with keys defined in spring.kafka.listener.*
.
The following component creates a listener endpoint on the someTopic
topic:
@Component
public class MyBean {
@KafkaListener(topics = "someTopic")
public void processMessage(String content) {
// ...
}
}
@Component
class MyBean {
@KafkaListener(topics = ["someTopic"])
fun processMessage(content: String?) {
// ...
}
}
If a KafkaTransactionManager
bean is defined, it is automatically associated to the container factory.
Similarly, if a RecordFilterStrategy
, CommonErrorHandler
, AfterRollbackProcessor
or ConsumerAwareRebalanceListener
bean is defined, it is automatically associated to the default factory.
Depending on the listener type, a RecordMessageConverter
or BatchMessageConverter
bean is associated to the default factory.
If only a RecordMessageConverter
bean is present for a batch listener, it is wrapped in a BatchMessageConverter
.
A custom ChainedKafkaTransactionManager must be marked @Primary as it usually references the auto-configured KafkaTransactionManager bean.
|
10.3.3. Kafka Streams
Spring for Apache Kafka provides a factory bean to create a StreamsBuilder
object and manage the lifecycle of its streams.
Spring Boot auto-configures the required KafkaStreamsConfiguration
bean as long as kafka-streams
is on the classpath and Kafka Streams is enabled by the @EnableKafkaStreams
annotation.
Enabling Kafka Streams means that the application id and bootstrap servers must be set.
The former can be configured using spring.kafka.streams.application-id
, defaulting to spring.application.name
if not set.
The latter can be set globally or specifically overridden only for streams.
Several additional properties are available using dedicated properties; other arbitrary Kafka properties can be set using the spring.kafka.streams.properties
namespace.
See also Additional Kafka Properties for more information.
To use the factory bean, wire StreamsBuilder
into your @Bean
as shown in the following example:
@Configuration(proxyBeanMethods = false)
@EnableKafkaStreams
public class MyKafkaStreamsConfiguration {
@Bean
public KStream<Integer, String> kStream(StreamsBuilder streamsBuilder) {
KStream<Integer, String> stream = streamsBuilder.stream("ks1In");
stream.map(this::uppercaseValue).to("ks1Out", Produced.with(Serdes.Integer(), new JsonSerde<>()));
return stream;
}
private KeyValue<Integer, String> uppercaseValue(Integer key, String value) {
return new KeyValue<>(key, value.toUpperCase());
}
}
@Configuration(proxyBeanMethods = false)
@EnableKafkaStreams
class MyKafkaStreamsConfiguration {
@Bean
fun kStream(streamsBuilder: StreamsBuilder): KStream<Int, String> {
val stream = streamsBuilder.stream<Int, String>("ks1In")
stream.map(this::uppercaseValue).to("ks1Out", Produced.with(Serdes.Integer(), JsonSerde()))
return stream
}
private fun uppercaseValue(key: Int, value: String): KeyValue<Int?, String?> {
return KeyValue(key, value.uppercase())
}
}
By default, the streams managed by the StreamBuilder
object are started automatically.
You can customize this behavior using the spring.kafka.streams.auto-startup
property.
10.3.4. Additional Kafka Properties
The properties supported by auto configuration are shown in the “Integration Properties” section of the Appendix. Note that, for the most part, these properties (hyphenated or camelCase) map directly to the Apache Kafka dotted properties. See the Apache Kafka documentation for details.
Properties that don’t include a client type (producer
, consumer
, admin
, or streams
) in their name are considered to be common and apply to all clients.
Most of these common properties can be overridden for one or more of the client types, if needed.
Apache Kafka designates properties with an importance of HIGH, MEDIUM, or LOW. Spring Boot auto-configuration supports all HIGH importance properties, some selected MEDIUM and LOW properties, and any properties that do not have a default value.
Only a subset of the properties supported by Kafka are available directly through the KafkaProperties
class.
If you wish to configure the individual client types with additional properties that are not directly supported, use the following properties:
spring.kafka.properties[prop.one]=first
spring.kafka.admin.properties[prop.two]=second
spring.kafka.consumer.properties[prop.three]=third
spring.kafka.producer.properties[prop.four]=fourth
spring.kafka.streams.properties[prop.five]=fifth
spring:
kafka:
properties:
"[prop.one]": "first"
admin:
properties:
"[prop.two]": "second"
consumer:
properties:
"[prop.three]": "third"
producer:
properties:
"[prop.four]": "fourth"
streams:
properties:
"[prop.five]": "fifth"
This sets the common prop.one
Kafka property to first
(applies to producers, consumers, admins, and streams), the prop.two
admin property to second
, the prop.three
consumer property to third
, the prop.four
producer property to fourth
and the prop.five
streams property to fifth
.
You can also configure the Spring Kafka JsonDeserializer
as follows:
spring.kafka.consumer.value-deserializer=org.springframework.kafka.support.serializer.JsonDeserializer
spring.kafka.consumer.properties[spring.json.value.default.type]=com.example.Invoice
spring.kafka.consumer.properties[spring.json.trusted.packages]=com.example.main,com.example.another
spring:
kafka:
consumer:
value-deserializer: "org.springframework.kafka.support.serializer.JsonDeserializer"
properties:
"[spring.json.value.default.type]": "com.example.Invoice"
"[spring.json.trusted.packages]": "com.example.main,com.example.another"
Similarly, you can disable the JsonSerializer
default behavior of sending type information in headers:
spring.kafka.producer.value-serializer=org.springframework.kafka.support.serializer.JsonSerializer
spring.kafka.producer.properties[spring.json.add.type.headers]=false
spring:
kafka:
producer:
value-serializer: "org.springframework.kafka.support.serializer.JsonSerializer"
properties:
"[spring.json.add.type.headers]": false
Properties set in this way override any configuration item that Spring Boot explicitly supports. |
10.3.5. Testing with Embedded Kafka
Spring for Apache Kafka provides a convenient way to test projects with an embedded Apache Kafka broker.
To use this feature, annotate a test class with @EmbeddedKafka
from the spring-kafka-test
module.
For more information, please see the Spring for Apache Kafka reference manual.
To make Spring Boot auto-configuration work with the aforementioned embedded Apache Kafka broker, you need to remap a system property for embedded broker addresses (populated by the EmbeddedKafkaBroker
) into the Spring Boot configuration property for Apache Kafka.
There are several ways to do that:
-
Provide a system property to map embedded broker addresses into
spring.kafka.bootstrap-servers
in the test class:
static {
System.setProperty(EmbeddedKafkaBroker.BROKER_LIST_PROPERTY, "spring.kafka.bootstrap-servers");
}
init {
System.setProperty(EmbeddedKafkaBroker.BROKER_LIST_PROPERTY, "spring.kafka.bootstrap-servers")
}
-
Configure a property name on the
@EmbeddedKafka
annotation:
@SpringBootTest
@EmbeddedKafka(topics = "someTopic", bootstrapServersProperty = "spring.kafka.bootstrap-servers")
class MyTest {
// ...
}
@SpringBootTest
@EmbeddedKafka(topics = ["someTopic"], bootstrapServersProperty = "spring.kafka.bootstrap-servers")
class MyTest {
// ...
}
-
Use a placeholder in configuration properties:
spring.kafka.bootstrap-servers=${spring.embedded.kafka.brokers}
spring:
kafka:
bootstrap-servers: "${spring.embedded.kafka.brokers}"
10.4. Apache Pulsar Support
Apache Pulsar is supported by providing auto-configuration of the Spring for Apache Pulsar project.
Spring Boot will auto-configure and register the classic (imperative) Spring for Apache Pulsar components when org.springframework.pulsar:spring-pulsar
is on the classpath.
It will do the same for the reactive components when org.springframework.pulsar:spring-pulsar-reactive
is on the classpath.
There are spring-boot-starter-pulsar
and spring-boot-starter-pulsar-reactive
“Starters” for conveniently collecting the dependencies for imperative and reactive use, respectively.
10.4.1. Connecting to Pulsar
When you use the Pulsar starter, Spring Boot will auto-configure and register a PulsarClient
bean.
By default, the application tries to connect to a local Pulsar instance at pulsar://localhost:6650
.
This can be adjusted by setting the spring.pulsar.client.service-url
property to a different value.
The value must be a valid Pulsar Protocol URL |
You can configure the client by specifying any of the spring.pulsar.client.*
prefixed application properties.
If you need more control over the configuration, consider registering one or more PulsarClientBuilderCustomizer
beans.
Authentication
To connect to a Pulsar cluster that requires authentication, you need to specify which authentication plugin to use by setting the pluginClassName
and any parameters required by the plugin.
You can set the parameters as a map of parameter names to parameter values.
The following example shows how to configure the AuthenticationOAuth2
plugin.
spring.pulsar.client.authentication.plugin-class-name=org.apache.pulsar.client.impl.auth.oauth2.AuthenticationOAuth2
spring.pulsar.client.authentication.param[issuerUrl]=https://auth.server.cloud/
spring.pulsar.client.authentication.param[privateKey]=file:///Users/some-key.json
spring.pulsar.client.authentication.param.audience=urn:sn:acme:dev:my-instance
spring:
pulsar:
client:
authentication:
plugin-class-name: org.apache.pulsar.client.impl.auth.oauth2.AuthenticationOAuth2
param:
issuerUrl: https://auth.server.cloud/
privateKey: file:///Users/some-key.json
audience: urn:sn:acme:dev:my-instance
You need to ensure that names defined under For example, if you want to configure the issuer url for the |
SSL
By default, Pulsar clients communicate with Pulsar services in plain text. You can follow these steps in the Spring for Apache Pulsar reference documentation to enable TLS encryption.
For complete details on the client and authentication see the Spring for Apache Pulsar reference documentation.
10.4.2. Connecting to Pulsar Reactively
When the Reactive auto-configuration is activated, Spring Boot will auto-configure and register a ReactivePulsarClient
bean.
The ReactivePulsarClient
adapts an instance of the previously described PulsarClient
.
Therefore, follow the previous section to configure the PulsarClient
used by the ReactivePulsarClient
.
10.4.3. Connecting to Pulsar Administration
Spring for Apache Pulsar’s PulsarAdministration
client is also auto-configured.
By default, the application tries to connect to a local Pulsar instance at http://localhost:8080
.
This can be adjusted by setting the spring.pulsar.admin.service-url
property to a different value in the form (http|https)://<host>:<port>
.
If you need more control over the configuration, consider registering one or more PulsarAdminBuilderCustomizer
beans.
Authentication
When accessing a Pulsar cluster that requires authentication, the admin client requires the same security configuration as the regular Pulsar client.
You can use the aforementioned authentication configuration by replacing spring.pulsar.client.authentication
with spring.pulsar.admin.authentication
.
To create a topic on startup, add a bean of type PulsarTopic .
If the topic already exists, the bean is ignored.
|
10.4.4. Sending a Message
Spring’s PulsarTemplate
is auto-configured, and you can use it to send messages, as shown in the following example:
@Component
public class MyBean {
private final PulsarTemplate<String> pulsarTemplate;
public MyBean(PulsarTemplate<String> pulsarTemplate) {
this.pulsarTemplate = pulsarTemplate;
}
public void someMethod() throws PulsarClientException {
this.pulsarTemplate.send("someTopic", "Hello");
}
}
@Component
class MyBean(private val pulsarTemplate: PulsarTemplate<String>) {
@Throws(PulsarClientException::class)
fun someMethod() {
pulsarTemplate.send("someTopic", "Hello")
}
}
The PulsarTemplate
relies on a PulsarProducerFactory
to create the underlying Pulsar producer.
Spring Boot auto-configuration also provides this producer factory, which by default, caches the producers that it creates.
You can configure the producer factory and cache settings by specifying any of the spring.pulsar.producer.*
and spring.pulsar.producer.cache.*
prefixed application properties.
If you need more control over the producer factory configuration, consider registering one or more ProducerBuilderCustomizer
beans.
These customizers are applied to all created producers.
You can also pass in a ProducerBuilderCustomizer
when sending a message to only affect the current producer.
If you need more control over the message being sent, you can pass in a TypedMessageBuilderCustomizer
when sending a message.
10.4.5. Sending a Message Reactively
When the Reactive auto-configuration is activated, Spring’s ReactivePulsarTemplate
is auto-configured, and you can use it to send messages, as shown in the following example:
@Component
public class MyBean {
private final ReactivePulsarTemplate<String> pulsarTemplate;
public MyBean(ReactivePulsarTemplate<String> pulsarTemplate) {
this.pulsarTemplate = pulsarTemplate;
}
public void someMethod() {
this.pulsarTemplate.send("someTopic", "Hello").subscribe();
}
}
@Component
class MyBean(private val pulsarTemplate: ReactivePulsarTemplate<String>) {
fun someMethod() {
pulsarTemplate.send("someTopic", "Hello").subscribe()
}
}
The ReactivePulsarTemplate
relies on a ReactivePulsarSenderFactory
to actually create the underlying sender.
Spring Boot auto-configuration also provides this sender factory, which by default, caches the producers that it creates.
You can configure the sender factory and cache settings by specifying any of the spring.pulsar.producer.*
and spring.pulsar.producer.cache.*
prefixed application properties.
If you need more control over the sender factory configuration, consider registering one or more ReactiveMessageSenderBuilderCustomizer
beans.
These customizers are applied to all created senders.
You can also pass in a ReactiveMessageSenderBuilderCustomizer
when sending a message to only affect the current sender.
If you need more control over the message being sent, you can pass in a MessageSpecBuilderCustomizer
when sending a message.
10.4.6. Receiving a Message
When the Apache Pulsar infrastructure is present, any bean can be annotated with @PulsarListener
to create a listener endpoint.
The following component creates a listener endpoint on the someTopic
topic:
@Component
public class MyBean {
@PulsarListener(topics = "someTopic")
public void processMessage(String content) {
// ...
}
}
@Component
class MyBean {
@PulsarListener(topics = ["someTopic"])
fun processMessage(content: String?) {
// ...
}
}
Spring Boot auto-configuration provides all the components necessary for PulsarListener
, such as the PulsarListenerContainerFactory
and the consumer factory it uses to construct the underlying Pulsar consumers.
You can configure these components by specifying any of the spring.pulsar.listener.*
and spring.pulsar.consumer.*
prefixed application properties.
If you need more control over the consumer factory configuration, consider registering one or more ConsumerBuilderCustomizer
beans.
These customizers are applied to all consumers created by the factory, and therefore all @PulsarListener
instances.
You can also customize a single listener by setting the consumerCustomizer
attribute of the @PulsarListener
annotation.
10.4.7. Receiving a Message Reactively
When the Apache Pulsar infrastructure is present and the Reactive auto-configuration is activated, any bean can be annotated with @ReactivePulsarListener
to create a reactive listener endpoint.
The following component creates a reactive listener endpoint on the someTopic
topic:
@Component
public class MyBean {
@ReactivePulsarListener(topics = "someTopic")
public Mono<Void> processMessage(String content) {
// ...
return Mono.empty();
}
}
@Component
class MyBean {
@ReactivePulsarListener(topics = ["someTopic"])
fun processMessage(content: String?): Mono<Void> {
// ...
return Mono.empty()
}
}
Spring Boot auto-configuration provides all the components necessary for ReactivePulsarListener
, such as the ReactivePulsarListenerContainerFactory
and the consumer factory it uses to construct the underlying reactive Pulsar consumers.
You can configure these components by specifying any of the spring.pulsar.listener.
and spring.pulsar.consumer.
prefixed application properties.
If you need more control over the consumer factory configuration, consider registering one or more ReactiveMessageConsumerBuilderCustomizer
beans.
These customizers are applied to all consumers created by the factory, and therefore all @ReactivePulsarListener
instances.
You can also customize a single listener by setting the consumerCustomizer
attribute of the @ReactivePulsarListener
annotation.
10.4.8. Reading a Message
The Pulsar reader interface enables applications to manually manage cursors. When you use a reader to connect to a topic you need to specify which message the reader begins reading from when it connects to a topic.
When the Apache Pulsar infrastructure is present, any bean can be annotated with @PulsarReader
to consume messages using a reader.
The following component creates a reader endpoint that starts reading messages from the beginning of the someTopic
topic:
@Component
public class MyBean {
@PulsarReader(topics = "someTopic", startMessageId = "earliest")
public void processMessage(String content) {
// ...
}
}
@Component
class MyBean {
@PulsarReader(topics = ["someTopic"], startMessageId = "earliest")
fun processMessage(content: String?) {
// ...
}
}
The @PulsarReader
relies on a PulsarReaderFactory
to create the underlying Pulsar reader.
Spring Boot auto-configuration provides this reader factory which can be customized by setting any of the spring.pulsar.reader.*
prefixed application properties.
If you need more control over the reader factory configuration, consider registering one or more ReaderBuilderCustomizer
beans.
These customizers are applied to all readers created by the factory, and therefore all @PulsarReader
instances.
You can also customize a single listener by setting the readerCustomizer
attribute of the @PulsarReader
annotation.
10.4.9. Reading a Message Reactively
When the Apache Pulsar infrastructure is present and the Reactive auto-configuration is activated, Spring’s ReactivePulsarReaderFactory
is provided, and you can use it to create a reader in order to read messages in a reactive fashion.
The following component creates a reader using the provided factory and reads a single message from 5 minutes ago from the someTopic
topic:
@Component
public class MyBean {
private final ReactivePulsarReaderFactory<String> pulsarReaderFactory;
public MyBean(ReactivePulsarReaderFactory<String> pulsarReaderFactory) {
this.pulsarReaderFactory = pulsarReaderFactory;
}
public void someMethod() {
ReactiveMessageReaderBuilderCustomizer<String> readerBuilderCustomizer = (readerBuilder) -> readerBuilder
.topic("someTopic")
.startAtSpec(StartAtSpec.ofInstant(Instant.now().minusSeconds(5)));
Mono<Message<String>> message = this.pulsarReaderFactory
.createReader(Schema.STRING, List.of(readerBuilderCustomizer))
.readOne();
// ...
}
}
@Component
class MyBean(private val pulsarReaderFactory: ReactivePulsarReaderFactory<String>) {
fun someMethod() {
val readerBuilderCustomizer = ReactiveMessageReaderBuilderCustomizer {
readerBuilder: ReactiveMessageReaderBuilder<String> ->
readerBuilder
.topic("someTopic")
.startAtSpec(StartAtSpec.ofInstant(Instant.now().minusSeconds(5)))
}
val message = pulsarReaderFactory
.createReader(Schema.STRING, listOf(readerBuilderCustomizer))
.readOne()
// ...
}
}
Spring Boot auto-configuration provides this reader factory which can be customized by setting any of the spring.pulsar.reader.*
prefixed application properties.
If you need more control over the reader factory configuration, consider passing in one or more ReactiveMessageReaderBuilderCustomizer
instances when using the factory to create a reader.
If you need more control over the reader factory configuration, consider registering one or more ReactiveMessageReaderBuilderCustomizer
beans.
These customizers are applied to all created readers.
You can also pass one or more ReactiveMessageReaderBuilderCustomizer
when creating a reader to only apply the customizations to the created reader.
For more details on any of the above components and to discover other available features, see the Spring for Apache Pulsar reference documentation. |
10.4.10. Additional Pulsar Properties
The properties supported by auto-configuration are shown in the “Integration Properties” section of the Appendix. Note that, for the most part, these properties (hyphenated or camelCase) map directly to the Apache Pulsar configuration properties. See the Apache Pulsar documentation for details.
Only a subset of the properties supported by Pulsar are available directly through the PulsarProperties
class.
If you wish to tune the auto-configured components with additional properties that are not directly supported, you can use the customizer supported by each aforementioned component.
10.5. RSocket
RSocket is a binary protocol for use on byte stream transports. It enables symmetric interaction models through async message passing over a single connection.
The spring-messaging
module of the Spring Framework provides support for RSocket requesters and responders, both on the client and on the server side.
See the RSocket section of the Spring Framework reference for more details, including an overview of the RSocket protocol.
10.5.1. RSocket Strategies Auto-configuration
Spring Boot auto-configures an RSocketStrategies
bean that provides all the required infrastructure for encoding and decoding RSocket payloads.
By default, the auto-configuration will try to configure the following (in order):
-
CBOR codecs with Jackson
-
JSON codecs with Jackson
The spring-boot-starter-rsocket
starter provides both dependencies.
See the Jackson support section to know more about customization possibilities.
Developers can customize the RSocketStrategies
component by creating beans that implement the RSocketStrategiesCustomizer
interface.
Note that their @Order
is important, as it determines the order of codecs.
10.5.2. RSocket server Auto-configuration
Spring Boot provides RSocket server auto-configuration.
The required dependencies are provided by the spring-boot-starter-rsocket
.
Spring Boot allows exposing RSocket over WebSocket from a WebFlux server, or standing up an independent RSocket server. This depends on the type of application and its configuration.
For WebFlux application (that is of type WebApplicationType.REACTIVE
), the RSocket server will be plugged into the Web Server only if the following properties match:
spring.rsocket.server.mapping-path=/rsocket
spring.rsocket.server.transport=websocket
spring:
rsocket:
server:
mapping-path: "/rsocket"
transport: "websocket"
Plugging RSocket into a web server is only supported with Reactor Netty, as RSocket itself is built with that library. |
Alternatively, an RSocket TCP or websocket server is started as an independent, embedded server. Besides the dependency requirements, the only required configuration is to define a port for that server:
spring.rsocket.server.port=9898
spring:
rsocket:
server:
port: 9898
10.5.3. Spring Messaging RSocket support
Spring Boot will auto-configure the Spring Messaging infrastructure for RSocket.
This means that Spring Boot will create a RSocketMessageHandler
bean that will handle RSocket requests to your application.
10.5.4. Calling RSocket Services with RSocketRequester
Once the RSocket
channel is established between server and client, any party can send or receive requests to the other.
As a server, you can get injected with an RSocketRequester
instance on any handler method of an RSocket @Controller
.
As a client, you need to configure and establish an RSocket connection first.
Spring Boot auto-configures an RSocketRequester.Builder
for such cases with the expected codecs and applies any RSocketConnectorConfigurer
bean.
The RSocketRequester.Builder
instance is a prototype bean, meaning each injection point will provide you with a new instance .
This is done on purpose since this builder is stateful and you should not create requesters with different setups using the same instance.
The following code shows a typical example:
@Service
public class MyService {
private final RSocketRequester rsocketRequester;
public MyService(RSocketRequester.Builder rsocketRequesterBuilder) {
this.rsocketRequester = rsocketRequesterBuilder.tcp("example.org", 9898);
}
public Mono<User> someRSocketCall(String name) {
return this.rsocketRequester.route("user").data(name).retrieveMono(User.class);
}
}
@Service
class MyService(rsocketRequesterBuilder: RSocketRequester.Builder) {
private val rsocketRequester: RSocketRequester
init {
rsocketRequester = rsocketRequesterBuilder.tcp("example.org", 9898)
}
fun someRSocketCall(name: String): Mono<User> {
return rsocketRequester.route("user").data(name).retrieveMono(
User::class.java
)
}
}
10.6. Spring Integration
Spring Boot offers several conveniences for working with Spring Integration, including the spring-boot-starter-integration
“Starter”.
Spring Integration provides abstractions over messaging and also other transports such as HTTP, TCP, and others.
If Spring Integration is available on your classpath, it is initialized through the @EnableIntegration
annotation.
Spring Integration polling logic relies on the auto-configured TaskScheduler
.
The default PollerMetadata
(poll unbounded number of messages every second) can be customized with spring.integration.poller.*
configuration properties.
Spring Boot also configures some features that are triggered by the presence of additional Spring Integration modules.
If spring-integration-jmx
is also on the classpath, message processing statistics are published over JMX.
If spring-integration-jdbc
is available, the default database schema can be created on startup, as shown in the following line:
spring.integration.jdbc.initialize-schema=always
spring:
integration:
jdbc:
initialize-schema: "always"
If spring-integration-rsocket
is available, developers can configure an RSocket server using "spring.rsocket.server.*"
properties and let it use IntegrationRSocketEndpoint
or RSocketOutboundGateway
components to handle incoming RSocket messages.
This infrastructure can handle Spring Integration RSocket channel adapters and @MessageMapping
handlers (given "spring.integration.rsocket.server.message-mapping-enabled"
is configured).
Spring Boot can also auto-configure an ClientRSocketConnector
using configuration properties:
# Connecting to a RSocket server over TCP
spring.integration.rsocket.client.host=example.org
spring.integration.rsocket.client.port=9898
# Connecting to a RSocket server over TCP
spring:
integration:
rsocket:
client:
host: "example.org"
port: 9898
# Connecting to a RSocket Server over WebSocket
spring.integration.rsocket.client.uri=ws://example.org
# Connecting to a RSocket Server over WebSocket
spring:
integration:
rsocket:
client:
uri: "ws://example.org"
See the IntegrationAutoConfiguration
and IntegrationProperties
classes for more details.
10.7. WebSockets
Spring Boot provides WebSockets auto-configuration for embedded Tomcat, Jetty, and Undertow. If you deploy a war file to a standalone container, Spring Boot assumes that the container is responsible for the configuration of its WebSocket support.
Spring Framework provides rich WebSocket support for MVC web applications that can be easily accessed through the spring-boot-starter-websocket
module.
WebSocket support is also available for reactive web applications and requires to include the WebSocket API alongside spring-boot-starter-webflux
:
<dependency>
<groupId>jakarta.websocket</groupId>
<artifactId>jakarta.websocket-api</artifactId>
</dependency>
10.8. What to Read Next
The next section describes how to enable IO capabilities in your application. You can read about caching, mail, validation, rest clients and more in this section.
11. IO
Most applications will need to deal with input and output concerns at some point. Spring Boot provides utilities and integrations with a range of technologies to help when you need IO capabilities. This section covers standard IO features such as caching and validation as well as more advanced topics such as scheduling and distributed transactions. We will also cover calling remote REST or SOAP services and sending email.
11.1. Caching
The Spring Framework provides support for transparently adding caching to an application.
At its core, the abstraction applies caching to methods, thus reducing the number of executions based on the information available in the cache.
The caching logic is applied transparently, without any interference to the invoker.
Spring Boot auto-configures the cache infrastructure as long as caching support is enabled by using the @EnableCaching
annotation.
Check the relevant section of the Spring Framework reference for more details. |
In a nutshell, to add caching to an operation of your service add the relevant annotation to its method, as shown in the following example:
@Component
public class MyMathService {
@Cacheable("piDecimals")
public int computePiDecimal(int precision) {
...
}
}
@Component
class MyMathService {
@Cacheable("piDecimals")
fun computePiDecimal(precision: Int): Int {
...
}
}
This example demonstrates the use of caching on a potentially costly operation.
Before invoking computePiDecimal
, the abstraction looks for an entry in the piDecimals
cache that matches the i
argument.
If an entry is found, the content in the cache is immediately returned to the caller, and the method is not invoked.
Otherwise, the method is invoked, and the cache is updated before returning the value.
You can also use the standard JSR-107 (JCache) annotations (such as @CacheResult ) transparently.
However, we strongly advise you to not mix and match the Spring Cache and JCache annotations.
|
If you do not add any specific cache library, Spring Boot auto-configures a simple provider that uses concurrent maps in memory.
When a cache is required (such as piDecimals
in the preceding example), this provider creates it for you.
The simple provider is not really recommended for production usage, but it is great for getting started and making sure that you understand the features.
When you have made up your mind about the cache provider to use, please make sure to read its documentation to figure out how to configure the caches that your application uses.
Nearly all providers require you to explicitly configure every cache that you use in the application.
Some offer a way to customize the default caches defined by the spring.cache.cache-names
property.
11.1.1. Supported Cache Providers
The cache abstraction does not provide an actual store and relies on abstraction materialized by the org.springframework.cache.Cache
and org.springframework.cache.CacheManager
interfaces.
If you have not defined a bean of type CacheManager
or a CacheResolver
named cacheResolver
(see CachingConfigurer
), Spring Boot tries to detect the following providers (in the indicated order):
-
JCache (JSR-107) (EhCache 3, Hazelcast, Infinispan, and others)
Additionally, Spring Boot for Apache Geode provides auto-configuration for using Apache Geode as a cache provider.
If the CacheManager is auto-configured by Spring Boot, it is possible to force a particular cache provider by setting the spring.cache.type property.
Use this property if you need to use no-op caches in certain environments (such as tests).
|
Use the spring-boot-starter-cache “Starter” to quickly add basic caching dependencies.
The starter brings in spring-context-support .
If you add dependencies manually, you must include spring-context-support in order to use the JCache or Caffeine support.
|
If the CacheManager
is auto-configured by Spring Boot, you can further tune its configuration before it is fully initialized by exposing a bean that implements the CacheManagerCustomizer
interface.
The following example sets a flag to say that null
values should not be passed down to the underlying map:
@Configuration(proxyBeanMethods = false)
public class MyCacheManagerConfiguration {
@Bean
public CacheManagerCustomizer<ConcurrentMapCacheManager> cacheManagerCustomizer() {
return (cacheManager) -> cacheManager.setAllowNullValues(false);
}
}
@Configuration(proxyBeanMethods = false)
class MyCacheManagerConfiguration {
@Bean
fun cacheManagerCustomizer(): CacheManagerCustomizer<ConcurrentMapCacheManager> {
return CacheManagerCustomizer { cacheManager ->
cacheManager.isAllowNullValues = false
}
}
}
In the preceding example, an auto-configured ConcurrentMapCacheManager is expected.
If that is not the case (either you provided your own config or a different cache provider was auto-configured), the customizer is not invoked at all.
You can have as many customizers as you want, and you can also order them by using @Order or Ordered .
|
Generic
Generic caching is used if the context defines at least one org.springframework.cache.Cache
bean.
A CacheManager
wrapping all beans of that type is created.
JCache (JSR-107)
JCache is bootstrapped through the presence of a javax.cache.spi.CachingProvider
on the classpath (that is, a JSR-107 compliant caching library exists on the classpath), and the JCacheCacheManager
is provided by the spring-boot-starter-cache
“Starter”.
Various compliant libraries are available, and Spring Boot provides dependency management for Ehcache 3, Hazelcast, and Infinispan.
Any other compliant library can be added as well.
It might happen that more than one provider is present, in which case the provider must be explicitly specified. Even if the JSR-107 standard does not enforce a standardized way to define the location of the configuration file, Spring Boot does its best to accommodate setting a cache with implementation details, as shown in the following example:
# Only necessary if more than one provider is present
spring.cache.jcache.provider=com.example.MyCachingProvider
spring.cache.jcache.config=classpath:example.xml
# Only necessary if more than one provider is present
spring:
cache:
jcache:
provider: "com.example.MyCachingProvider"
config: "classpath:example.xml"
When a cache library offers both a native implementation and JSR-107 support, Spring Boot prefers the JSR-107 support, so that the same features are available if you switch to a different JSR-107 implementation. |
Spring Boot has general support for Hazelcast.
If a single HazelcastInstance is available, it is automatically reused for the CacheManager as well, unless the spring.cache.jcache.config property is specified.
|
There are two ways to customize the underlying javax.cache.cacheManager
:
-
Caches can be created on startup by setting the
spring.cache.cache-names
property. If a customjavax.cache.configuration.Configuration
bean is defined, it is used to customize them. -
org.springframework.boot.autoconfigure.cache.JCacheManagerCustomizer
beans are invoked with the reference of theCacheManager
for full customization.
If a standard javax.cache.CacheManager bean is defined, it is wrapped automatically in an org.springframework.cache.CacheManager implementation that the abstraction expects.
No further customization is applied to it.
|
Hazelcast
Spring Boot has general support for Hazelcast.
If a HazelcastInstance
has been auto-configured and com.hazelcast:hazelcast-spring
is on the classpath, it is automatically wrapped in a CacheManager
.
Hazelcast can be used as a JCache compliant cache or as a Spring CacheManager compliant cache.
When setting spring.cache.type to hazelcast , Spring Boot will use the CacheManager based implementation.
If you want to use Hazelcast as a JCache compliant cache, set spring.cache.type to jcache .
If you have multiple JCache compliant cache providers and want to force the use of Hazelcast, you have to explicitly set the JCache provider.
|
Infinispan
Infinispan has no default configuration file location, so it must be specified explicitly. Otherwise, the default bootstrap is used.
spring.cache.infinispan.config=infinispan.xml
spring:
cache:
infinispan:
config: "infinispan.xml"
Caches can be created on startup by setting the spring.cache.cache-names
property.
If a custom ConfigurationBuilder
bean is defined, it is used to customize the caches.
To be compatible with Spring Boot’s Jakarta EE 9 baseline, Infinispan’s -jakarta
modules must be used.
For every module with a -jakarta
variant, the variant must be used in place of the standard module.
For example, infinispan-core-jakarta
and infinispan-commons-jakarta
must be used in place of infinispan-core
and infinispan-commons
respectively.
Couchbase
If Spring Data Couchbase is available and Couchbase is configured, a CouchbaseCacheManager
is auto-configured.
It is possible to create additional caches on startup by setting the spring.cache.cache-names
property and cache defaults can be configured by using spring.cache.couchbase.*
properties.
For instance, the following configuration creates cache1
and cache2
caches with an entry expiration of 10 minutes:
spring.cache.cache-names=cache1,cache2
spring.cache.couchbase.expiration=10m
spring:
cache:
cache-names: "cache1,cache2"
couchbase:
expiration: "10m"
If you need more control over the configuration, consider registering a CouchbaseCacheManagerBuilderCustomizer
bean.
The following example shows a customizer that configures a specific entry expiration for cache1
and cache2
:
@Configuration(proxyBeanMethods = false)
public class MyCouchbaseCacheManagerConfiguration {
@Bean
public CouchbaseCacheManagerBuilderCustomizer myCouchbaseCacheManagerBuilderCustomizer() {
return (builder) -> builder
.withCacheConfiguration("cache1", CouchbaseCacheConfiguration
.defaultCacheConfig().entryExpiry(Duration.ofSeconds(10)))
.withCacheConfiguration("cache2", CouchbaseCacheConfiguration
.defaultCacheConfig().entryExpiry(Duration.ofMinutes(1)));
}
}
@Configuration(proxyBeanMethods = false)
class MyCouchbaseCacheManagerConfiguration {
@Bean
fun myCouchbaseCacheManagerBuilderCustomizer(): CouchbaseCacheManagerBuilderCustomizer {
return CouchbaseCacheManagerBuilderCustomizer { builder ->
builder
.withCacheConfiguration(
"cache1", CouchbaseCacheConfiguration
.defaultCacheConfig().entryExpiry(Duration.ofSeconds(10))
)
.withCacheConfiguration(
"cache2", CouchbaseCacheConfiguration
.defaultCacheConfig().entryExpiry(Duration.ofMinutes(1))
)
}
}
}
Redis
If Redis is available and configured, a RedisCacheManager
is auto-configured.
It is possible to create additional caches on startup by setting the spring.cache.cache-names
property and cache defaults can be configured by using spring.cache.redis.*
properties.
For instance, the following configuration creates cache1
and cache2
caches with a time to live of 10 minutes:
spring.cache.cache-names=cache1,cache2
spring.cache.redis.time-to-live=10m
spring:
cache:
cache-names: "cache1,cache2"
redis:
time-to-live: "10m"
By default, a key prefix is added so that, if two separate caches use the same key, Redis does not have overlapping keys and cannot return invalid values.
We strongly recommend keeping this setting enabled if you create your own RedisCacheManager .
|
You can take full control of the default configuration by adding a RedisCacheConfiguration @Bean of your own.
This can be useful if you need to customize the default serialization strategy.
|
If you need more control over the configuration, consider registering a RedisCacheManagerBuilderCustomizer
bean.
The following example shows a customizer that configures a specific time to live for cache1
and cache2
:
@Configuration(proxyBeanMethods = false)
public class MyRedisCacheManagerConfiguration {
@Bean
public RedisCacheManagerBuilderCustomizer myRedisCacheManagerBuilderCustomizer() {
return (builder) -> builder
.withCacheConfiguration("cache1", RedisCacheConfiguration
.defaultCacheConfig().entryTtl(Duration.ofSeconds(10)))
.withCacheConfiguration("cache2", RedisCacheConfiguration
.defaultCacheConfig().entryTtl(Duration.ofMinutes(1)));
}
}
@Configuration(proxyBeanMethods = false)
class MyRedisCacheManagerConfiguration {
@Bean
fun myRedisCacheManagerBuilderCustomizer(): RedisCacheManagerBuilderCustomizer {
return RedisCacheManagerBuilderCustomizer { builder ->
builder
.withCacheConfiguration(
"cache1", RedisCacheConfiguration
.defaultCacheConfig().entryTtl(Duration.ofSeconds(10))
)
.withCacheConfiguration(
"cache2", RedisCacheConfiguration
.defaultCacheConfig().entryTtl(Duration.ofMinutes(1))
)
}
}
}
Caffeine
Caffeine is a Java 8 rewrite of Guava’s cache that supersedes support for Guava.
If Caffeine is present, a CaffeineCacheManager
(provided by the spring-boot-starter-cache
“Starter”) is auto-configured.
Caches can be created on startup by setting the spring.cache.cache-names
property and can be customized by one of the following (in the indicated order):
-
A cache spec defined by
spring.cache.caffeine.spec
-
A
com.github.benmanes.caffeine.cache.CaffeineSpec
bean is defined -
A
com.github.benmanes.caffeine.cache.Caffeine
bean is defined
For instance, the following configuration creates cache1
and cache2
caches with a maximum size of 500 and a time to live of 10 minutes
spring.cache.cache-names=cache1,cache2
spring.cache.caffeine.spec=maximumSize=500,expireAfterAccess=600s
spring:
cache:
cache-names: "cache1,cache2"
caffeine:
spec: "maximumSize=500,expireAfterAccess=600s"
If a com.github.benmanes.caffeine.cache.CacheLoader
bean is defined, it is automatically associated to the CaffeineCacheManager
.
Since the CacheLoader
is going to be associated with all caches managed by the cache manager, it must be defined as CacheLoader<Object, Object>
.
The auto-configuration ignores any other generic type.
Cache2k
Cache2k is an in-memory cache.
If the Cache2k spring integration is present, a SpringCache2kCacheManager
is auto-configured.
Caches can be created on startup by setting the spring.cache.cache-names
property.
Cache defaults can be customized using a Cache2kBuilderCustomizer
bean.
The following example shows a customizer that configures the capacity of the cache to 200 entries, with an expiration of 5 minutes:
@Configuration(proxyBeanMethods = false)
public class MyCache2kDefaultsConfiguration {
@Bean
public Cache2kBuilderCustomizer myCache2kDefaultsCustomizer() {
return (builder) -> builder.entryCapacity(200)
.expireAfterWrite(5, TimeUnit.MINUTES);
}
}
@Configuration(proxyBeanMethods = false)
class MyCache2kDefaultsConfiguration {
@Bean
fun myCache2kDefaultsCustomizer(): Cache2kBuilderCustomizer {
return Cache2kBuilderCustomizer { builder ->
builder.entryCapacity(200)
.expireAfterWrite(5, TimeUnit.MINUTES)
}
}
}
Simple
If none of the other providers can be found, a simple implementation using a ConcurrentHashMap
as the cache store is configured.
This is the default if no caching library is present in your application.
By default, caches are created as needed, but you can restrict the list of available caches by setting the cache-names
property.
For instance, if you want only cache1
and cache2
caches, set the cache-names
property as follows:
spring.cache.cache-names=cache1,cache2
spring:
cache:
cache-names: "cache1,cache2"
If you do so and your application uses a cache not listed, then it fails at runtime when the cache is needed, but not on startup. This is similar to the way the "real" cache providers behave if you use an undeclared cache.
None
When @EnableCaching
is present in your configuration, a suitable cache configuration is expected as well.
If you have a custom CacheManager
, consider defining it in a separate @Configuration
class so that you can override it if necessary.
None uses a no-op implementation that is useful in tests, and slice tests use that by default via @AutoConfigureCache
.
If you need to use a no-op cache rather than the auto-configured cache manager in a certain environment, set the cache type to none
, as shown in the following example:
spring.cache.type=none
spring:
cache:
type: "none"
11.2. Hazelcast
If Hazelcast is on the classpath and a suitable configuration is found, Spring Boot auto-configures a HazelcastInstance
that you can inject in your application.
Spring Boot first attempts to create a client by checking the following configuration options:
-
The presence of a
com.hazelcast.client.config.ClientConfig
bean. -
A configuration file defined by the
spring.hazelcast.config
property. -
The presence of the
hazelcast.client.config
system property. -
A
hazelcast-client.xml
in the working directory or at the root of the classpath. -
A
hazelcast-client.yaml
(orhazelcast-client.yml
) in the working directory or at the root of the classpath.
If a client can not be created, Spring Boot attempts to configure an embedded server.
If you define a com.hazelcast.config.Config
bean, Spring Boot uses that.
If your configuration defines an instance name, Spring Boot tries to locate an existing instance rather than creating a new one.
You could also specify the Hazelcast configuration file to use through configuration, as shown in the following example:
spring.hazelcast.config=classpath:config/my-hazelcast.xml
spring:
hazelcast:
config: "classpath:config/my-hazelcast.xml"
Otherwise, Spring Boot tries to find the Hazelcast configuration from the default locations: hazelcast.xml
in the working directory or at the root of the classpath, or a YAML counterpart in the same locations.
We also check if the hazelcast.config
system property is set.
See the Hazelcast documentation for more details.
By default, @SpringAware on Hazelcast components is supported.
The ManagementContext can be overridden by declaring a HazelcastConfigCustomizer bean with an @Order higher than zero.
|
Spring Boot also has explicit caching support for Hazelcast.
If caching is enabled, the HazelcastInstance is automatically wrapped in a CacheManager implementation.
|
11.3. Quartz Scheduler
Spring Boot offers several conveniences for working with the Quartz scheduler, including the spring-boot-starter-quartz
“Starter”.
If Quartz is available, a Scheduler
is auto-configured (through the SchedulerFactoryBean
abstraction).
Beans of the following types are automatically picked up and associated with the Scheduler
:
-
JobDetail
: defines a particular Job.JobDetail
instances can be built with theJobBuilder
API. -
Calendar
. -
Trigger
: defines when a particular job is triggered.
By default, an in-memory JobStore
is used.
However, it is possible to configure a JDBC-based store if a DataSource
bean is available in your application and if the spring.quartz.job-store-type
property is configured accordingly, as shown in the following example:
spring.quartz.job-store-type=jdbc
spring:
quartz:
job-store-type: "jdbc"
When the JDBC store is used, the schema can be initialized on startup, as shown in the following example:
spring.quartz.jdbc.initialize-schema=always
spring:
quartz:
jdbc:
initialize-schema: "always"
By default, the database is detected and initialized by using the standard scripts provided with the Quartz library.
These scripts drop existing tables, deleting all triggers on every restart.
It is also possible to provide a custom script by setting the spring.quartz.jdbc.schema property.
|
To have Quartz use a DataSource
other than the application’s main DataSource
, declare a DataSource
bean, annotating its @Bean
method with @QuartzDataSource
.
Doing so ensures that the Quartz-specific DataSource
is used by both the SchedulerFactoryBean
and for schema initialization.
Similarly, to have Quartz use a TransactionManager
other than the application’s main TransactionManager
declare a TransactionManager
bean, annotating its @Bean
method with @QuartzTransactionManager
.
By default, jobs created by configuration will not overwrite already registered jobs that have been read from a persistent job store.
To enable overwriting existing job definitions set the spring.quartz.overwrite-existing-jobs
property.
Quartz Scheduler configuration can be customized using spring.quartz
properties and SchedulerFactoryBeanCustomizer
beans, which allow programmatic SchedulerFactoryBean
customization.
Advanced Quartz configuration properties can be customized using spring.quartz.properties.*
.
In particular, an Executor bean is not associated with the scheduler as Quartz offers a way to configure the scheduler through spring.quartz.properties .
If you need to customize the task executor, consider implementing SchedulerFactoryBeanCustomizer .
|
Jobs can define setters to inject data map properties. Regular beans can also be injected in a similar manner, as shown in the following example:
public class MySampleJob extends QuartzJobBean {
// Inject "MyService" bean
public void setMyService(MyService myService) {
this.myService = myService;
}
// Inject the "name" job data property
public void setName(String name) {
this.name = name;
}
@Override
protected void executeInternal(JobExecutionContext context) throws JobExecutionException {
this.myService.someMethod(context.getFireTime(), this.name);
}
}
class MySampleJob : QuartzJobBean() {
// Inject "MyService" bean
fun setMyService(myService: MyService?) {
this.myService = myService
}
// Inject the "name" job data property
fun setName(name: String?) {
this.name = name
}
override fun executeInternal(context: JobExecutionContext) {
myService!!.someMethod(context.fireTime, name)
}
}
11.4. Sending Email
The Spring Framework provides an abstraction for sending email by using the JavaMailSender
interface, and Spring Boot provides auto-configuration for it as well as a starter module.
See the reference documentation for a detailed explanation of how you can use JavaMailSender .
|
If spring.mail.host
and the relevant libraries (as defined by spring-boot-starter-mail
) are available, a default JavaMailSender
is created if none exists.
The sender can be further customized by configuration items from the spring.mail
namespace.
See MailProperties
for more details.
In particular, certain default timeout values are infinite, and you may want to change that to avoid having a thread blocked by an unresponsive mail server, as shown in the following example:
spring.mail.properties[mail.smtp.connectiontimeout]=5000
spring.mail.properties[mail.smtp.timeout]=3000
spring.mail.properties[mail.smtp.writetimeout]=5000
spring:
mail:
properties:
"[mail.smtp.connectiontimeout]": 5000
"[mail.smtp.timeout]": 3000
"[mail.smtp.writetimeout]": 5000
It is also possible to configure a JavaMailSender
with an existing Session
from JNDI:
spring.mail.jndi-name=mail/Session
spring:
mail:
jndi-name: "mail/Session"
When a jndi-name
is set, it takes precedence over all other Session-related settings.
11.5. Validation
The method validation feature supported by Bean Validation 1.1 is automatically enabled as long as a JSR-303 implementation (such as Hibernate validator) is on the classpath.
This lets bean methods be annotated with jakarta.validation
constraints on their parameters and/or on their return value.
Target classes with such annotated methods need to be annotated with the @Validated
annotation at the type level for their methods to be searched for inline constraint annotations.
For instance, the following service triggers the validation of the first argument, making sure its size is between 8 and 10:
@Service
@Validated
public class MyBean {
public Archive findByCodeAndAuthor(@Size(min = 8, max = 10) String code, Author author) {
return ...
}
}
@Service
@Validated
class MyBean {
fun findByCodeAndAuthor(code: @Size(min = 8, max = 10) String?, author: Author?): Archive? {
return null
}
}
The application’s MessageSource
is used when resolving {parameters}
in constraint messages.
This allows you to use your application’s messages.properties
files for Bean Validation messages.
Once the parameters have been resolved, message interpolation is completed using Bean Validation’s default interpolator.
To customize the Configuration
used to build the ValidatorFactory
, define a ValidationConfigurationCustomizer
bean.
When multiple customizer beans are defined, they are called in order based on their @Order
annotation or Ordered
implementation.
11.6. Calling REST Services
Spring Boot provides various convenient ways to call remote REST services.
If you are developing a non-blocking reactive application and you’re using Spring WebFlux, then you can use WebClient
.
If you prefer blocking APIs then you can use RestClient
or RestTemplate
.
11.6.1. WebClient
If you have Spring WebFlux on your classpath we recommend that you use WebClient
to call remote REST services.
The WebClient
interface provides a functional style API and is fully reactive.
You can learn more about the WebClient
in the dedicated section in the Spring Framework docs.
If you are not writing a reactive Spring WebFlux application you can use the RestClient instead of a WebClient .
This provides a similar functional API, but is blocking rather than reactive.
|
Spring Boot creates and pre-configures a prototype WebClient.Builder
bean for you.
It is strongly advised to inject it in your components and use it to create WebClient
instances.
Spring Boot is configuring that builder to share HTTP resources and reflect codecs setup in the same fashion as the server ones (see WebFlux HTTP codecs auto-configuration), and more.
The following code shows a typical example:
@Service
public class MyService {
private final WebClient webClient;
public MyService(WebClient.Builder webClientBuilder) {
this.webClient = webClientBuilder.baseUrl("https://example.org").build();
}
public Mono<Details> someRestCall(String name) {
return this.webClient.get().uri("/{name}/details", name).retrieve().bodyToMono(Details.class);
}
}
@Service
class MyService(webClientBuilder: WebClient.Builder) {
private val webClient: WebClient
init {
webClient = webClientBuilder.baseUrl("https://example.org").build()
}
fun someRestCall(name: String?): Mono<Details> {
return webClient.get().uri("/{name}/details", name)
.retrieve().bodyToMono(Details::class.java)
}
}
WebClient Runtime
Spring Boot will auto-detect which ClientHttpConnector
to use to drive WebClient
depending on the libraries available on the application classpath.
In order of preference, the following clients are supported:
-
Reactor Netty
-
Jetty RS client
-
Apache HttpClient
-
JDK HttpClient
If multiple clients are available on the classpath, the most preferred client will be used.
The spring-boot-starter-webflux
starter depends on io.projectreactor.netty:reactor-netty
by default, which brings both server and client implementations.
If you choose to use Jetty as a reactive server instead, you should add a dependency on the Jetty Reactive HTTP client library, org.eclipse.jetty:jetty-reactive-httpclient
.
Using the same technology for server and client has its advantages, as it will automatically share HTTP resources between client and server.
Developers can override the resource configuration for Jetty and Reactor Netty by providing a custom ReactorResourceFactory
or JettyResourceFactory
bean - this will be applied to both clients and servers.
If you wish to override that choice for the client, you can define your own ClientHttpConnector
bean and have full control over the client configuration.
You can learn more about the WebClient
configuration options in the Spring Framework reference documentation.
WebClient Customization
There are three main approaches to WebClient
customization, depending on how broadly you want the customizations to apply.
To make the scope of any customizations as narrow as possible, inject the auto-configured WebClient.Builder
and then call its methods as required.
WebClient.Builder
instances are stateful: Any change on the builder is reflected in all clients subsequently created with it.
If you want to create several clients with the same builder, you can also consider cloning the builder with WebClient.Builder other = builder.clone();
.
To make an application-wide, additive customization to all WebClient.Builder
instances, you can declare WebClientCustomizer
beans and change the WebClient.Builder
locally at the point of injection.
Finally, you can fall back to the original API and use WebClient.create()
.
In that case, no auto-configuration or WebClientCustomizer
is applied.
WebClient SSL Support
If you need custom SSL configuration on the ClientHttpConnector
used by the WebClient
, you can inject a WebClientSsl
instance that can be used with the builder’s apply
method.
The WebClientSsl
interface provides access to any SSL bundles that you have defined in your application.properties
or application.yaml
file.
The following code shows a typical example:
@Service
public class MyService {
private final WebClient webClient;
public MyService(WebClient.Builder webClientBuilder, WebClientSsl ssl) {
this.webClient = webClientBuilder.baseUrl("https://example.org").apply(ssl.fromBundle("mybundle")).build();
}
public Mono<Details> someRestCall(String name) {
return this.webClient.get().uri("/{name}/details", name).retrieve().bodyToMono(Details.class);
}
}
@Service
class MyService(webClientBuilder: WebClient.Builder, ssl: WebClientSsl) {
private val webClient: WebClient
init {
webClient = webClientBuilder.baseUrl("https://example.org")
.apply(ssl.fromBundle("mybundle")).build()
}
fun someRestCall(name: String?): Mono<Details> {
return webClient.get().uri("/{name}/details", name)
.retrieve().bodyToMono(Details::class.java)
}
}
11.6.2. RestClient
If you are not using Spring WebFlux or Project Reactor in your application we recommend that you use RestClient
to call remote REST services.
The RestClient
interface provides a functional style blocking API.
Spring Boot creates and pre-configures a prototype RestClient.Builder
bean for you.
It is strongly advised to inject it in your components and use it to create RestClient
instances.
Spring Boot is configuring that builder with HttpMessageConverters
and an appropriate ClientHttpRequestFactory
.
The following code shows a typical example:
@Service
public class MyService {
private final RestClient restClient;
public MyService(RestClient.Builder restClientBuilder) {
this.restClient = restClientBuilder.baseUrl("https://example.org").build();
}
public Details someRestCall(String name) {
return this.restClient.get().uri("/{name}/details", name).retrieve().body(Details.class);
}
}
@Service
class MyService(restClientBuilder: RestClient.Builder) {
private val restClient: RestClient
init {
restClient = restClientBuilder.baseUrl("https://example.org").build()
}
fun someRestCall(name: String?): Details {
return restClient.get().uri("/{name}/details", name)
.retrieve().body(Details::class.java)!!
}
}
RestClient Customization
There are three main approaches to RestClient
customization, depending on how broadly you want the customizations to apply.
To make the scope of any customizations as narrow as possible, inject the auto-configured RestClient.Builder
and then call its methods as required.
RestClient.Builder
instances are stateful: Any change on the builder is reflected in all clients subsequently created with it.
If you want to create several clients with the same builder, you can also consider cloning the builder with RestClient.Builder other = builder.clone();
.
To make an application-wide, additive customization to all RestClient.Builder
instances, you can declare RestClientCustomizer
beans and change the RestClient.Builder
locally at the point of injection.
Finally, you can fall back to the original API and use RestClient.create()
.
In that case, no auto-configuration or RestClientCustomizer
is applied.
RestClient SSL Support
If you need custom SSL configuration on the ClientHttpRequestFactory
used by the RestClient
, you can inject a RestClientSsl
instance that can be used with the builder’s apply
method.
The RestClientSsl
interface provides access to any SSL bundles that you have defined in your application.properties
or application.yaml
file.
The following code shows a typical example:
@Service
public class MyService {
private final RestClient restClient;
public MyService(RestClient.Builder restClientBuilder, RestClientSsl ssl) {
this.restClient = restClientBuilder.baseUrl("https://example.org").apply(ssl.fromBundle("mybundle")).build();
}
public Details someRestCall(String name) {
return this.restClient.get().uri("/{name}/details", name).retrieve().body(Details.class);
}
}
@Service
class MyService(restClientBuilder: RestClient.Builder, ssl: RestClientSsl) {
private val restClient: RestClient
init {
restClient = restClientBuilder.baseUrl("https://example.org")
.apply(ssl.fromBundle("mybundle")).build()
}
fun someRestCall(name: String?): Details {
return restClient.get().uri("/{name}/details", name)
.retrieve().body(Details::class.java)!!
}
}
If you need to apply other customization in addition to an SSL bundle, you can use the ClientHttpRequestFactorySettings
class with ClientHttpRequestFactories
:
@Service
public class MyService {
private final RestClient restClient;
public MyService(RestClient.Builder restClientBuilder, SslBundles sslBundles) {
ClientHttpRequestFactorySettings settings = ClientHttpRequestFactorySettings.DEFAULTS
.withReadTimeout(Duration.ofMinutes(2))
.withSslBundle(sslBundles.getBundle("mybundle"));
ClientHttpRequestFactory requestFactory = ClientHttpRequestFactories.get(settings);
this.restClient = restClientBuilder.baseUrl("https://example.org").requestFactory(requestFactory).build();
}
public Details someRestCall(String name) {
return this.restClient.get().uri("/{name}/details", name).retrieve().body(Details.class);
}
}
@Service
class MyService(restClientBuilder: RestClient.Builder, sslBundles: SslBundles) {
private val restClient: RestClient
init {
val settings = ClientHttpRequestFactorySettings.DEFAULTS
.withReadTimeout(Duration.ofMinutes(2))
.withSslBundle(sslBundles.getBundle("mybundle"))
val requestFactory = ClientHttpRequestFactories.get(settings)
restClient = restClientBuilder
.baseUrl("https://example.org")
.requestFactory(requestFactory).build()
}
fun someRestCall(name: String?): Details {
return restClient.get().uri("/{name}/details", name).retrieve().body(Details::class.java)!!
}
}
11.6.3. RestTemplate
Spring Framework’s RestTemplate
class predates RestClient
and is the classic way that many applications use to call remote REST services.
You might choose to use RestTemplate
when you have existing code that you don’t want to migrate to RestClient
, or because you’re already familiar with the RestTemplate
API.
Since RestTemplate
instances often need to be customized before being used, Spring Boot does not provide any single auto-configured RestTemplate
bean.
It does, however, auto-configure a RestTemplateBuilder
, which can be used to create RestTemplate
instances when needed.
The auto-configured RestTemplateBuilder
ensures that sensible HttpMessageConverters
and an appropriate ClientHttpRequestFactory
are applied to RestTemplate
instances.
The following code shows a typical example:
@Service
public class MyService {
private final RestTemplate restTemplate;
public MyService(RestTemplateBuilder restTemplateBuilder) {
this.restTemplate = restTemplateBuilder.build();
}
public Details someRestCall(String name) {
return this.restTemplate.getForObject("/{name}/details", Details.class, name);
}
}
@Service
class MyService(restTemplateBuilder: RestTemplateBuilder) {
private val restTemplate: RestTemplate
init {
restTemplate = restTemplateBuilder.build()
}
fun someRestCall(name: String): Details {
return restTemplate.getForObject("/{name}/details", Details::class.java, name)!!
}
}
RestTemplateBuilder
includes a number of useful methods that can be used to quickly configure a RestTemplate
.
For example, to add BASIC authentication support, you can use builder.basicAuthentication("user", "password").build()
.
RestTemplate Customization
There are three main approaches to RestTemplate
customization, depending on how broadly you want the customizations to apply.
To make the scope of any customizations as narrow as possible, inject the auto-configured RestTemplateBuilder
and then call its methods as required.
Each method call returns a new RestTemplateBuilder
instance, so the customizations only affect this use of the builder.
To make an application-wide, additive customization, use a RestTemplateCustomizer
bean.
All such beans are automatically registered with the auto-configured RestTemplateBuilder
and are applied to any templates that are built with it.
The following example shows a customizer that configures the use of a proxy for all hosts except 192.168.0.5
:
public class MyRestTemplateCustomizer implements RestTemplateCustomizer {
@Override
public void customize(RestTemplate restTemplate) {
HttpRoutePlanner routePlanner = new CustomRoutePlanner(new HttpHost("proxy.example.com"));
HttpClient httpClient = HttpClientBuilder.create().setRoutePlanner(routePlanner).build();
restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory(httpClient));
}
static class CustomRoutePlanner extends DefaultProxyRoutePlanner {
CustomRoutePlanner(HttpHost proxy) {
super(proxy);
}
@Override
protected HttpHost determineProxy(HttpHost target, HttpContext context) throws HttpException {
if (target.getHostName().equals("192.168.0.5")) {
return null;
}
return super.determineProxy(target, context);
}
}
}
class MyRestTemplateCustomizer : RestTemplateCustomizer {
override fun customize(restTemplate: RestTemplate) {
val routePlanner: HttpRoutePlanner = CustomRoutePlanner(HttpHost("proxy.example.com"))
val httpClient: HttpClient = HttpClientBuilder.create().setRoutePlanner(routePlanner).build()
restTemplate.requestFactory = HttpComponentsClientHttpRequestFactory(httpClient)
}
internal class CustomRoutePlanner(proxy: HttpHost?) : DefaultProxyRoutePlanner(proxy) {
@Throws(HttpException::class)
public override fun determineProxy(target: HttpHost, context: HttpContext): HttpHost? {
if (target.hostName == "192.168.0.5") {
return null
}
return super.determineProxy(target, context)
}
}
}
Finally, you can define your own RestTemplateBuilder
bean.
Doing so will replace the auto-configured builder.
If you want any RestTemplateCustomizer
beans to be applied to your custom builder, as the auto-configuration would have done, configure it using a RestTemplateBuilderConfigurer
.
The following example exposes a RestTemplateBuilder
that matches what Spring Boot’s auto-configuration would have done, except that custom connect and read timeouts are also specified:
@Configuration(proxyBeanMethods = false)
public class MyRestTemplateBuilderConfiguration {
@Bean
public RestTemplateBuilder restTemplateBuilder(RestTemplateBuilderConfigurer configurer) {
return configurer.configure(new RestTemplateBuilder())
.setConnectTimeout(Duration.ofSeconds(5))
.setReadTimeout(Duration.ofSeconds(2));
}
}
@Configuration(proxyBeanMethods = false)
class MyRestTemplateBuilderConfiguration {
@Bean
fun restTemplateBuilder(configurer: RestTemplateBuilderConfigurer): RestTemplateBuilder {
return configurer.configure(RestTemplateBuilder()).setConnectTimeout(Duration.ofSeconds(5))
.setReadTimeout(Duration.ofSeconds(2))
}
}
The most extreme (and rarely used) option is to create your own RestTemplateBuilder
bean without using a configurer.
In addition to replacing the auto-configured builder, this also prevents any RestTemplateCustomizer
beans from being used.
RestTemplate SSL Support
If you need custom SSL configuration on the RestTemplate
, you can apply an SSL bundle to the RestTemplateBuilder
as shown in this example:
@Service
public class MyService {
private final RestTemplate restTemplate;
public MyService(RestTemplateBuilder restTemplateBuilder, SslBundles sslBundles) {
this.restTemplate = restTemplateBuilder.setSslBundle(sslBundles.getBundle("mybundle")).build();
}
public Details someRestCall(String name) {
return this.restTemplate.getForObject("/{name}/details", Details.class, name);
}
}
@Service
class MyService(restTemplateBuilder: RestTemplateBuilder, sslBundles: SslBundles) {
private val restTemplate: RestTemplate
init {
restTemplate = restTemplateBuilder.setSslBundle(sslBundles.getBundle("mybundle")).build()
}
fun someRestCall(name: String): Details {
return restTemplate.getForObject("/{name}/details", Details::class.java, name)!!
}
}
11.6.4. HTTP Client Detection for RestClient and RestTemplate
Spring Boot will auto-detect which HTTP client to use with RestClient
and RestTemplate
depending on the libraries available on the application classpath.
In order of preference, the following clients are supported:
-
Apache HttpClient
-
Jetty HttpClient
-
OkHttp (deprecated)
-
Simple JDK client (
HttpURLConnection
)
If multiple clients are available on the classpath, the most preferred client will be used.
11.7. Web Services
Spring Boot provides Web Services auto-configuration so that all you must do is define your Endpoints
.
The Spring Web Services features can be easily accessed with the spring-boot-starter-webservices
module.
SimpleWsdl11Definition
and SimpleXsdSchema
beans can be automatically created for your WSDLs and XSDs respectively.
To do so, configure their location, as shown in the following example:
spring.webservices.wsdl-locations=classpath:/wsdl
spring:
webservices:
wsdl-locations: "classpath:/wsdl"
11.7.1. Calling Web Services with WebServiceTemplate
If you need to call remote Web services from your application, you can use the WebServiceTemplate
class.
Since WebServiceTemplate
instances often need to be customized before being used, Spring Boot does not provide any single auto-configured WebServiceTemplate
bean.
It does, however, auto-configure a WebServiceTemplateBuilder
, which can be used to create WebServiceTemplate
instances when needed.
The following code shows a typical example:
@Service
public class MyService {
private final WebServiceTemplate webServiceTemplate;
public MyService(WebServiceTemplateBuilder webServiceTemplateBuilder) {
this.webServiceTemplate = webServiceTemplateBuilder.build();
}
public SomeResponse someWsCall(SomeRequest detailsReq) {
return (SomeResponse) this.webServiceTemplate.marshalSendAndReceive(detailsReq,
new SoapActionCallback("https://ws.example.com/action"));
}
}
@Service
class MyService(webServiceTemplateBuilder: WebServiceTemplateBuilder) {
private val webServiceTemplate: WebServiceTemplate
init {
webServiceTemplate = webServiceTemplateBuilder.build()
}
fun someWsCall(detailsReq: SomeRequest?): SomeResponse {
return webServiceTemplate.marshalSendAndReceive(
detailsReq,
SoapActionCallback("https://ws.example.com/action")
) as SomeResponse
}
}
By default, WebServiceTemplateBuilder
detects a suitable HTTP-based WebServiceMessageSender
using the available HTTP client libraries on the classpath.
You can also customize read and connection timeouts as follows:
@Configuration(proxyBeanMethods = false)
public class MyWebServiceTemplateConfiguration {
@Bean
public WebServiceTemplate webServiceTemplate(WebServiceTemplateBuilder builder) {
WebServiceMessageSender sender = new HttpWebServiceMessageSenderBuilder()
.setConnectTimeout(Duration.ofSeconds(5))
.setReadTimeout(Duration.ofSeconds(2))
.build();
return builder.messageSenders(sender).build();
}
}
@Configuration(proxyBeanMethods = false)
class MyWebServiceTemplateConfiguration {
@Bean
fun webServiceTemplate(builder: WebServiceTemplateBuilder): WebServiceTemplate {
val sender = HttpWebServiceMessageSenderBuilder()
.setConnectTimeout(Duration.ofSeconds(5))
.setReadTimeout(Duration.ofSeconds(2))
.build()
return builder.messageSenders(sender).build()
}
}
11.8. Distributed Transactions With JTA
Spring Boot supports distributed JTA transactions across multiple XA resources by using a transaction manager retrieved from JNDI.
When a JTA environment is detected, Spring’s JtaTransactionManager
is used to manage transactions.
Auto-configured JMS, DataSource, and JPA beans are upgraded to support XA transactions.
You can use standard Spring idioms, such as @Transactional
, to participate in a distributed transaction.
If you are within a JTA environment and still want to use local transactions, you can set the spring.jta.enabled
property to false
to disable the JTA auto-configuration.
11.8.1. Using a Jakarta EE Managed Transaction Manager
If you package your Spring Boot application as a war
or ear
file and deploy it to a Jakarta EE application server, you can use your application server’s built-in transaction manager.
Spring Boot tries to auto-configure a transaction manager by looking at common JNDI locations (java:comp/UserTransaction
, java:comp/TransactionManager
, and so on).
When using a transaction service provided by your application server, you generally also want to ensure that all resources are managed by the server and exposed over JNDI.
Spring Boot tries to auto-configure JMS by looking for a ConnectionFactory
at the JNDI path (java:/JmsXA
or java:/XAConnectionFactory
), and you can use the spring.datasource.jndi-name
property to configure your DataSource
.
11.8.2. Mixing XA and Non-XA JMS Connections
When using JTA, the primary JMS ConnectionFactory
bean is XA-aware and participates in distributed transactions.
You can inject into your bean without needing to use any @Qualifier
:
public MyBean(ConnectionFactory connectionFactory) {
// ...
}
In some situations, you might want to process certain JMS messages by using a non-XA ConnectionFactory
.
For example, your JMS processing logic might take longer than the XA timeout.
If you want to use a non-XA ConnectionFactory
, you can the nonXaJmsConnectionFactory
bean:
public MyBean(@Qualifier("nonXaJmsConnectionFactory") ConnectionFactory connectionFactory) {
// ...
}
For consistency, the jmsConnectionFactory
bean is also provided by using the bean alias xaJmsConnectionFactory
:
public MyBean(@Qualifier("xaJmsConnectionFactory") ConnectionFactory connectionFactory) {
// ...
}
11.8.3. Supporting an Embedded Transaction Manager
The XAConnectionFactoryWrapper
and XADataSourceWrapper
interfaces can be used to support embedded transaction managers.
The interfaces are responsible for wrapping XAConnectionFactory
and XADataSource
beans and exposing them as regular ConnectionFactory
and DataSource
beans, which transparently enroll in the distributed transaction.
DataSource and JMS auto-configuration use JTA variants, provided you have a JtaTransactionManager
bean and appropriate XA wrapper beans registered within your ApplicationContext
.
11.9. What to Read Next
You should now have a good understanding of Spring Boot’s core features and the various technologies that Spring Boot provides support for through auto-configuration.
The next few sections go into detail about deploying applications to cloud platforms. You can read about building container images in the next section or skip to the production-ready features section.
12. Container Images
Spring Boot applications can be containerized using Dockerfiles, or by using Cloud Native Buildpacks to create optimized docker compatible container images that you can run anywhere.
12.1. Efficient Container Images
It is easily possible to package a Spring Boot uber jar as a docker image. However, there are various downsides to copying and running the uber jar as is in the docker image. There’s always a certain amount of overhead when running a uber jar without unpacking it, and in a containerized environment this can be noticeable. The other issue is that putting your application’s code and all its dependencies in one layer in the Docker image is sub-optimal. Since you probably recompile your code more often than you upgrade the version of Spring Boot you use, it’s often better to separate things a bit more. If you put jar files in the layer before your application classes, Docker often only needs to change the very bottom layer and can pick others up from its cache.
12.1.1. Layering Docker Images
To make it easier to create optimized Docker images, Spring Boot supports adding a layer index file to the jar. It provides a list of layers and the parts of the jar that should be contained within them. The list of layers in the index is ordered based on the order in which the layers should be added to the Docker/OCI image. Out-of-the-box, the following layers are supported:
-
dependencies
(for regular released dependencies) -
spring-boot-loader
(for everything underorg/springframework/boot/loader
) -
snapshot-dependencies
(for snapshot dependencies) -
application
(for application classes and resources)
The following shows an example of a layers.idx
file:
- "dependencies":
- BOOT-INF/lib/library1.jar
- BOOT-INF/lib/library2.jar
- "spring-boot-loader":
- org/springframework/boot/loader/launch/JarLauncher.class
- ... <other classes>
- "snapshot-dependencies":
- BOOT-INF/lib/library3-SNAPSHOT.jar
- "application":
- META-INF/MANIFEST.MF
- BOOT-INF/classes/a/b/C.class
This layering is designed to separate code based on how likely it is to change between application builds. Library code is less likely to change between builds, so it is placed in its own layers to allow tooling to re-use the layers from cache. Application code is more likely to change between builds so it is isolated in a separate layer.
Spring Boot also supports layering for war files with the help of a layers.idx
.
For Maven, see the packaging layered jar or war section for more details on adding a layer index to the archive. For Gradle, see the packaging layered jar or war section of the Gradle plugin documentation.
12.2. Dockerfiles
While it is possible to convert a Spring Boot uber jar into a docker image with just a few lines in the Dockerfile, we will use the layering feature to create an optimized docker image.
When you create a jar containing the layers index file, the spring-boot-jarmode-layertools
jar will be added as a dependency to your jar.
With this jar on the classpath, you can launch your application in a special mode which allows the bootstrap code to run something entirely different from your application, for example, something that extracts the layers.
The layertools mode can not be used with a fully executable Spring Boot archive that includes a launch script.
Disable launch script configuration when building a jar file that is intended to be used with layertools .
|
Here’s how you can launch your jar with a layertools
jar mode:
$ java -Djarmode=layertools -jar my-app.jar
This will provide the following output:
Usage: java -Djarmode=layertools -jar my-app.jar Available commands: list List layers from the jar that can be extracted extract Extracts layers from the jar for image creation help Help about any command
The extract
command can be used to easily split the application into layers to be added to the dockerfile.
Here is an example of a Dockerfile using jarmode
.
FROM eclipse-temurin:17-jre as builder
WORKDIR application
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} application.jar
RUN java -Djarmode=layertools -jar application.jar extract
FROM eclipse-temurin:17-jre
WORKDIR application
COPY --from=builder application/dependencies/ ./
COPY --from=builder application/spring-boot-loader/ ./
COPY --from=builder application/snapshot-dependencies/ ./
COPY --from=builder application/application/ ./
ENTRYPOINT ["java", "org.springframework.boot.loader.launch.JarLauncher"]
Assuming the above Dockerfile
is in the current directory, your docker image can be built with docker build .
, or optionally specifying the path to your application jar, as shown in the following example:
$ docker build --build-arg JAR_FILE=path/to/myapp.jar .
This is a multi-stage dockerfile.
The builder stage extracts the directories that are needed later.
Each of the COPY
commands relates to the layers extracted by the jarmode.
Of course, a Dockerfile can be written without using the jarmode.
You can use some combination of unzip
and mv
to move things to the right layer but jarmode simplifies that.
12.3. Cloud Native Buildpacks
Dockerfiles are just one way to build docker images.
Another way to build docker images is directly from your Maven or Gradle plugin, using buildpacks.
If you’ve ever used an application platform such as Cloud Foundry or Heroku then you’ve probably used a buildpack.
Buildpacks are the part of the platform that takes your application and converts it into something that the platform can actually run.
For example, Cloud Foundry’s Java buildpack will notice that you’re pushing a .jar
file and automatically add a relevant JRE.
With Cloud Native Buildpacks, you can create Docker compatible images that you can run anywhere. Spring Boot includes buildpack support directly for both Maven and Gradle. This means you can just type a single command and quickly get a sensible image into your locally running Docker daemon.
The Paketo Spring Boot buildpack supports the layers.idx file, so any customization that is applied to it will be reflected in the image created by the buildpack.
|
In order to achieve reproducible builds and container image caching, Buildpacks can manipulate the application resources metadata (such as the file "last modified" information).
You should ensure that your application does not rely on that metadata at runtime.
Spring Boot can use that information when serving static resources, but this can be disabled with spring.web.resources.cache.use-last-modified .
|
12.4. What to Read Next
Once you’ve learned how to build efficient container images, you can read about deploying applications to a cloud platform, such as Kubernetes.
13. Production-ready Features
Spring Boot includes a number of additional features to help you monitor and manage your application when you push it to production. You can choose to manage and monitor your application by using HTTP endpoints or with JMX. Auditing, health, and metrics gathering can also be automatically applied to your application.
13.1. Enabling Production-ready Features
The spring-boot-actuator
module provides all of Spring Boot’s production-ready features.
The recommended way to enable the features is to add a dependency on the spring-boot-starter-actuator
“Starter”.
To add the actuator to a Maven-based project, add the following “Starter” dependency:
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
</dependencies>
For Gradle, use the following declaration:
dependencies {
implementation 'org.springframework.boot:spring-boot-starter-actuator'
}
13.2. Endpoints
Actuator endpoints let you monitor and interact with your application.
Spring Boot includes a number of built-in endpoints and lets you add your own.
For example, the health
endpoint provides basic application health information.
You can enable or disable each individual endpoint and expose them (make them remotely accessible) over HTTP or JMX.
An endpoint is considered to be available when it is both enabled and exposed.
The built-in endpoints are auto-configured only when they are available.
Most applications choose exposure over HTTP, where the ID of the endpoint and a prefix of /actuator
is mapped to a URL.
For example, by default, the health
endpoint is mapped to /actuator/health
.
To learn more about the Actuator’s endpoints and their request and response formats, see the separate API documentation (HTML or PDF). |
The following technology-agnostic endpoints are available:
ID | Description |
---|---|
|
Exposes audit events information for the current application.
Requires an |
|
Displays a complete list of all the Spring beans in your application. |
|
Exposes available caches. |
|
Shows the conditions that were evaluated on configuration and auto-configuration classes and the reasons why they did or did not match. |
|
Displays a collated list of all |
|
Exposes properties from Spring’s |
|
Shows any Flyway database migrations that have been applied.
Requires one or more |
|
Shows application health information. |
|
Displays HTTP exchange information (by default, the last 100 HTTP request-response exchanges).
Requires an |
|
Displays arbitrary application info. |
|
Shows the Spring Integration graph.
Requires a dependency on |
|
Shows and modifies the configuration of loggers in the application. |
|
Shows any Liquibase database migrations that have been applied.
Requires one or more |
|
Shows “metrics” information for the current application. |
|
Displays a collated list of all |
|
Shows information about Quartz Scheduler jobs. Subject to sanitization. |
|
Displays the scheduled tasks in your application. |
|
Allows retrieval and deletion of user sessions from a Spring Session-backed session store. Requires a servlet-based web application that uses Spring Session. |
|
Lets the application be gracefully shutdown. Only works when using jar packaging. Disabled by default. |
|
Shows the startup steps data collected by the |
|
Performs a thread dump. |
If your application is a web application (Spring MVC, Spring WebFlux, or Jersey), you can use the following additional endpoints:
ID | Description |
---|---|
|
Returns a heap dump file.
On a HotSpot JVM, an |
|
Returns the contents of the logfile (if the |
|
Exposes metrics in a format that can be scraped by a Prometheus server.
Requires a dependency on |
13.2.1. Enabling Endpoints
By default, all endpoints except for shutdown
are enabled.
To configure the enablement of an endpoint, use its management.endpoint.<id>.enabled
property.
The following example enables the shutdown
endpoint:
management.endpoint.shutdown.enabled=true
management:
endpoint:
shutdown:
enabled: true
If you prefer endpoint enablement to be opt-in rather than opt-out, set the management.endpoints.enabled-by-default
property to false
and use individual endpoint enabled
properties to opt back in.
The following example enables the info
endpoint and disables all other endpoints:
management.endpoints.enabled-by-default=false
management.endpoint.info.enabled=true
management:
endpoints:
enabled-by-default: false
endpoint:
info:
enabled: true
Disabled endpoints are removed entirely from the application context.
If you want to change only the technologies over which an endpoint is exposed, use the include and exclude properties instead.
|
13.2.2. Exposing Endpoints
By default, only the health endpoint is exposed over HTTP and JMX. Since Endpoints may contain sensitive information, you should carefully consider when to expose them.
To change which endpoints are exposed, use the following technology-specific include
and exclude
properties:
Property | Default |
---|---|
|
|
|
|
|
|
|
|
The include
property lists the IDs of the endpoints that are exposed.
The exclude
property lists the IDs of the endpoints that should not be exposed.
The exclude
property takes precedence over the include
property.
You can configure both the include
and the exclude
properties with a list of endpoint IDs.
For example, to only expose the health
and info
endpoints over JMX, use the following property:
management.endpoints.jmx.exposure.include=health,info
management:
endpoints:
jmx:
exposure:
include: "health,info"
*
can be used to select all endpoints.
For example, to expose everything over HTTP except the env
and beans
endpoints, use the following properties:
management.endpoints.web.exposure.include=*
management.endpoints.web.exposure.exclude=env,beans
management:
endpoints:
web:
exposure:
include: "*"
exclude: "env,beans"
* has a special meaning in YAML, so be sure to add quotation marks if you want to include (or exclude) all endpoints.
|
If your application is exposed publicly, we strongly recommend that you also secure your endpoints. |
If you want to implement your own strategy for when endpoints are exposed, you can register an EndpointFilter bean.
|
13.2.3. Security
For security purposes, only the /health
endpoint is exposed over HTTP by default.
You can use the management.endpoints.web.exposure.include
property to configure the endpoints that are exposed.
Before setting the management.endpoints.web.exposure.include , ensure that the exposed actuators do not contain sensitive information, are secured by placing them behind a firewall, or are secured by something like Spring Security.
|
If Spring Security is on the classpath and no other SecurityFilterChain
bean is present, all actuators other than /health
are secured by Spring Boot auto-configuration.
If you define a custom SecurityFilterChain
bean, Spring Boot auto-configuration backs off and lets you fully control the actuator access rules.
If you wish to configure custom security for HTTP endpoints (for example, to allow only users with a certain role to access them), Spring Boot provides some convenient RequestMatcher
objects that you can use in combination with Spring Security.
A typical Spring Security configuration might look something like the following example:
@Configuration(proxyBeanMethods = false)
public class MySecurityConfiguration {
@Bean
public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
http.securityMatcher(EndpointRequest.toAnyEndpoint());
http.authorizeHttpRequests((requests) -> requests.anyRequest().hasRole("ENDPOINT_ADMIN"));
http.httpBasic(withDefaults());
return http.build();
}
}
@Configuration(proxyBeanMethods = false)
class MySecurityConfiguration {
@Bean
fun securityFilterChain(http: HttpSecurity): SecurityFilterChain {
http.securityMatcher(EndpointRequest.toAnyEndpoint()).authorizeHttpRequests { requests ->
requests.anyRequest().hasRole("ENDPOINT_ADMIN")
}
http.httpBasic(withDefaults())
return http.build()
}
}
The preceding example uses EndpointRequest.toAnyEndpoint()
to match a request to any endpoint and then ensures that all have the ENDPOINT_ADMIN
role.
Several other matcher methods are also available on EndpointRequest
.
See the API documentation (HTML or PDF) for details.
If you deploy applications behind a firewall, you may prefer that all your actuator endpoints can be accessed without requiring authentication.
You can do so by changing the management.endpoints.web.exposure.include
property, as follows:
management.endpoints.web.exposure.include=*
management:
endpoints:
web:
exposure:
include: "*"
Additionally, if Spring Security is present, you would need to add custom security configuration that allows unauthenticated access to the endpoints, as the following example shows:
@Configuration(proxyBeanMethods = false)
public class MySecurityConfiguration {
@Bean
public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
http.securityMatcher(EndpointRequest.toAnyEndpoint());
http.authorizeHttpRequests((requests) -> requests.anyRequest().permitAll());
return http.build();
}
}
@Configuration(proxyBeanMethods = false)
class MySecurityConfiguration {
@Bean
fun securityFilterChain(http: HttpSecurity): SecurityFilterChain {
http.securityMatcher(EndpointRequest.toAnyEndpoint()).authorizeHttpRequests { requests ->
requests.anyRequest().permitAll()
}
return http.build()
}
}
In both of the preceding examples, the configuration applies only to the actuator endpoints.
Since Spring Boot’s security configuration backs off completely in the presence of any SecurityFilterChain bean, you need to configure an additional SecurityFilterChain bean with rules that apply to the rest of the application.
|
Cross Site Request Forgery Protection
Since Spring Boot relies on Spring Security’s defaults, CSRF protection is turned on by default.
This means that the actuator endpoints that require a POST
(shutdown and loggers endpoints), a PUT
, or a DELETE
get a 403 (forbidden) error when the default security configuration is in use.
We recommend disabling CSRF protection completely only if you are creating a service that is used by non-browser clients. |
You can find additional information about CSRF protection in the Spring Security Reference Guide.
13.2.4. Configuring Endpoints
Endpoints automatically cache responses to read operations that do not take any parameters.
To configure the amount of time for which an endpoint caches a response, use its cache.time-to-live
property.
The following example sets the time-to-live of the beans
endpoint’s cache to 10 seconds:
management.endpoint.beans.cache.time-to-live=10s
management:
endpoint:
beans:
cache:
time-to-live: "10s"
The management.endpoint.<name> prefix uniquely identifies the endpoint that is being configured.
|
13.2.5. Sanitize Sensitive Values
Information returned by the /env
, /configprops
and /quartz
endpoints can be somewhat sensitive.
All values are sanitized by default (that is replaced by ******
).
Viewing original values in the unsanitized form can be configured per endpoint using the showValues
property for that endpoint.
This property can be configured to have the following values:
-
ALWAYS
- all values are shown in their unsanitized form to all users -
NEVER
- all values are always sanitized (that is replaced by******
) -
WHEN_AUTHORIZED
- all values are shown in their unsanitized form to authorized users
For HTTP endpoints, a user is considered to be authorized if they have authenticated and have the roles configured by the endpoint’s roles property. By default, any authenticated user is authorized. For JMX endpoints, all users are always authorized.
management.endpoint.env.show-values=WHEN_AUTHORIZED
management.endpoint.env.roles=admin
management:
endpoint:
env:
show-values: WHEN_AUTHORIZED
roles: "admin"
The configuration above enables the ability for all users with the admin
role to view all values in their original form from the /env
endpoint.
When show-values is set to ALWAYS or WHEN_AUTHORIZED any sanitization applied by a SanitizingFunction will still be applied.
|
13.2.6. Hypermedia for Actuator Web Endpoints
A “discovery page” is added with links to all the endpoints.
The “discovery page” is available on /actuator
by default.
To disable the “discovery page”, add the following property to your application properties:
management.endpoints.web.discovery.enabled=false
management:
endpoints:
web:
discovery:
enabled: false
When a custom management context path is configured, the “discovery page” automatically moves from /actuator
to the root of the management context.
For example, if the management context path is /management
, the discovery page is available from /management
.
When the management context path is set to /
, the discovery page is disabled to prevent the possibility of a clash with other mappings.
13.2.7. CORS Support
Cross-origin resource sharing (CORS) is a W3C specification that lets you specify in a flexible way what kind of cross-domain requests are authorized. If you use Spring MVC or Spring WebFlux, you can configure Actuator’s web endpoints to support such scenarios.
CORS support is disabled by default and is only enabled once you have set the management.endpoints.web.cors.allowed-origins
property.
The following configuration permits GET
and POST
calls from the example.com
domain:
management.endpoints.web.cors.allowed-origins=https://example.com
management.endpoints.web.cors.allowed-methods=GET,POST
management:
endpoints:
web:
cors:
allowed-origins: "https://example.com"
allowed-methods: "GET,POST"
See CorsEndpointProperties for a complete list of options.
|
13.2.8. Implementing Custom Endpoints
If you add a @Bean
annotated with @Endpoint
, any methods annotated with @ReadOperation
, @WriteOperation
, or @DeleteOperation
are automatically exposed over JMX and, in a web application, over HTTP as well.
Endpoints can be exposed over HTTP by using Jersey, Spring MVC, or Spring WebFlux.
If both Jersey and Spring MVC are available, Spring MVC is used.
The following example exposes a read operation that returns a custom object:
@ReadOperation
public CustomData getData() {
return new CustomData("test", 5);
}
@ReadOperation
fun getData(): CustomData {
return CustomData("test", 5)
}
You can also write technology-specific endpoints by using @JmxEndpoint
or @WebEndpoint
.
These endpoints are restricted to their respective technologies.
For example, @WebEndpoint
is exposed only over HTTP and not over JMX.
You can write technology-specific extensions by using @EndpointWebExtension
and @EndpointJmxExtension
.
These annotations let you provide technology-specific operations to augment an existing endpoint.
Finally, if you need access to web-framework-specific functionality, you can implement servlet or Spring @Controller
and @RestController
endpoints at the cost of them not being available over JMX or when using a different web framework.
Receiving Input
Operations on an endpoint receive input through their parameters.
When exposed over the web, the values for these parameters are taken from the URL’s query parameters and from the JSON request body.
When exposed over JMX, the parameters are mapped to the parameters of the MBean’s operations.
Parameters are required by default.
They can be made optional by annotating them with either @javax.annotation.Nullable
or @org.springframework.lang.Nullable
.
You can map each root property in the JSON request body to a parameter of the endpoint. Consider the following JSON request body:
{
"name": "test",
"counter": 42
}
You can use this to invoke a write operation that takes String name
and int counter
parameters, as the following example shows:
@WriteOperation
public void updateData(String name, int counter) {
// injects "test" and 42
}
@WriteOperation
fun updateData(name: String?, counter: Int) {
// injects "test" and 42
}
Because endpoints are technology agnostic, only simple types can be specified in the method signature.
In particular, declaring a single parameter with a CustomData type that defines a name and counter properties is not supported.
|
To let the input be mapped to the operation method’s parameters, Java code that implements an endpoint should be compiled with -parameters , and Kotlin code that implements an endpoint should be compiled with -java-parameters .
This will happen automatically if you use Spring Boot’s Gradle plugin or if you use Maven and spring-boot-starter-parent .
|
Input Type Conversion
The parameters passed to endpoint operation methods are, if necessary, automatically converted to the required type.
Before calling an operation method, the input received over JMX or HTTP is converted to the required types by using an instance of ApplicationConversionService
as well as any Converter
or GenericConverter
beans qualified with @EndpointConverter
.
Custom Web Endpoints
Operations on an @Endpoint
, @WebEndpoint
, or @EndpointWebExtension
are automatically exposed over HTTP using Jersey, Spring MVC, or Spring WebFlux.
If both Jersey and Spring MVC are available, Spring MVC is used.
Web Endpoint Request Predicates
A request predicate is automatically generated for each operation on a web-exposed endpoint.
Path
The path of the predicate is determined by the ID of the endpoint and the base path of the web-exposed endpoints.
The default base path is /actuator
.
For example, an endpoint with an ID of sessions
uses /actuator/sessions
as its path in the predicate.
You can further customize the path by annotating one or more parameters of the operation method with @Selector
.
Such a parameter is added to the path predicate as a path variable.
The variable’s value is passed into the operation method when the endpoint operation is invoked.
If you want to capture all remaining path elements, you can add @Selector(Match=ALL_REMAINING)
to the last parameter and make it a type that is conversion-compatible with a String[]
.
HTTP method
The HTTP method of the predicate is determined by the operation type, as shown in the following table:
Operation | HTTP method |
---|---|
|
|
|
|
|
|
Consumes
For a @WriteOperation
(HTTP POST
) that uses the request body, the consumes
clause of the predicate is application/vnd.spring-boot.actuator.v2+json, application/json
.
For all other operations, the consumes
clause is empty.
Produces
The produces
clause of the predicate can be determined by the produces
attribute of the @DeleteOperation
, @ReadOperation
, and @WriteOperation
annotations.
The attribute is optional.
If it is not used, the produces
clause is determined automatically.
If the operation method returns void
or Void
, the produces
clause is empty.
If the operation method returns a org.springframework.core.io.Resource
, the produces
clause is application/octet-stream
.
For all other operations, the produces
clause is application/vnd.spring-boot.actuator.v2+json, application/json
.
Web Endpoint Response Status
The default response status for an endpoint operation depends on the operation type (read, write, or delete) and what, if anything, the operation returns.
If a @ReadOperation
returns a value, the response status will be 200 (OK).
If it does not return a value, the response status will be 404 (Not Found).
If a @WriteOperation
or @DeleteOperation
returns a value, the response status will be 200 (OK).
If it does not return a value, the response status will be 204 (No Content).
If an operation is invoked without a required parameter or with a parameter that cannot be converted to the required type, the operation method is not called, and the response status will be 400 (Bad Request).
Web Endpoint Range Requests
You can use an HTTP range request to request part of an HTTP resource.
When using Spring MVC or Spring Web Flux, operations that return a org.springframework.core.io.Resource
automatically support range requests.
Range requests are not supported when using Jersey. |
Web Endpoint Security
An operation on a web endpoint or a web-specific endpoint extension can receive the current java.security.Principal
or org.springframework.boot.actuate.endpoint.SecurityContext
as a method parameter.
The former is typically used in conjunction with @Nullable
to provide different behavior for authenticated and unauthenticated users.
The latter is typically used to perform authorization checks by using its isUserInRole(String)
method.
Servlet Endpoints
A servlet can be exposed as an endpoint by implementing a class annotated with @ServletEndpoint
that also implements Supplier<EndpointServlet>
.
Servlet endpoints provide deeper integration with the servlet container but at the expense of portability.
They are intended to be used to expose an existing servlet as an endpoint.
For new endpoints, the @Endpoint
and @WebEndpoint
annotations should be preferred whenever possible.
Controller Endpoints
You can use @ControllerEndpoint
and @RestControllerEndpoint
to implement an endpoint that is exposed only by Spring MVC or Spring WebFlux.
Methods are mapped by using the standard annotations for Spring MVC and Spring WebFlux, such as @RequestMapping
and @GetMapping
, with the endpoint’s ID being used as a prefix for the path.
Controller endpoints provide deeper integration with Spring’s web frameworks but at the expense of portability.
The @Endpoint
and @WebEndpoint
annotations should be preferred whenever possible.
13.2.9. Health Information
You can use health information to check the status of your running application.
It is often used by monitoring software to alert someone when a production system goes down.
The information exposed by the health
endpoint depends on the management.endpoint.health.show-details
and management.endpoint.health.show-components
properties, which can be configured with one of the following values:
Name | Description |
---|---|
|
Details are never shown. |
|
Details are shown only to authorized users.
Authorized roles can be configured by using |
|
Details are shown to all users. |
The default value is never
.
A user is considered to be authorized when they are in one or more of the endpoint’s roles.
If the endpoint has no configured roles (the default), all authenticated users are considered to be authorized.
You can configure the roles by using the management.endpoint.health.roles
property.
If you have secured your application and wish to use always , your security configuration must permit access to the health endpoint for both authenticated and unauthenticated users.
|
Health information is collected from the content of a HealthContributorRegistry
(by default, all HealthContributor
instances defined in your ApplicationContext
).
Spring Boot includes a number of auto-configured HealthContributors
, and you can also write your own.
A HealthContributor
can be either a HealthIndicator
or a CompositeHealthContributor
.
A HealthIndicator
provides actual health information, including a Status
.
A CompositeHealthContributor
provides a composite of other HealthContributors
.
Taken together, contributors form a tree structure to represent the overall system health.
By default, the final system health is derived by a StatusAggregator
, which sorts the statuses from each HealthIndicator
based on an ordered list of statuses.
The first status in the sorted list is used as the overall health status.
If no HealthIndicator
returns a status that is known to the StatusAggregator
, an UNKNOWN
status is used.
You can use the HealthContributorRegistry to register and unregister health indicators at runtime.
|
Auto-configured HealthIndicators
When appropriate, Spring Boot auto-configures the HealthIndicators
listed in the following table.
You can also enable or disable selected indicators by configuring management.health.key.enabled
,
with the key
listed in the following table:
Key | Name | Description |
---|---|---|
|
Checks that a Cassandra database is up. |
|
|
Checks that a Couchbase cluster is up. |
|
|
Checks that a connection to |
|
|
Checks for low disk space. |
|
|
Checks that an Elasticsearch cluster is up. |
|
|
Checks that a Hazelcast server is up. |
|
|
Checks that an InfluxDB server is up. |
|
|
Checks that a JMS broker is up. |
|
|
Checks that an LDAP server is up. |
|
|
Checks that a mail server is up. |
|
|
Checks that a Mongo database is up. |
|
|
Checks that a Neo4j database is up. |
|
|
Always responds with |
|
|
Checks that a Rabbit server is up. |
|
|
Checks that a Redis server is up. |
You can disable them all by setting the management.health.defaults.enabled property.
|
Additional HealthIndicators
are available but are not enabled by default:
Key | Name | Description |
---|---|---|
|
Exposes the “Liveness” application availability state. |
|
|
Exposes the “Readiness” application availability state. |
Writing Custom HealthIndicators
To provide custom health information, you can register Spring beans that implement the HealthIndicator
interface.
You need to provide an implementation of the health()
method and return a Health
response.
The Health
response should include a status and can optionally include additional details to be displayed.
The following code shows a sample HealthIndicator
implementation:
@Component
public class MyHealthIndicator implements HealthIndicator {
@Override
public Health health() {
int errorCode = check();
if (errorCode != 0) {
return Health.down().withDetail("Error Code", errorCode).build();
}
return Health.up().build();
}
private int check() {
// perform some specific health check
return ...
}
}
@Component
class MyHealthIndicator : HealthIndicator {
override fun health(): Health {
val errorCode = check()
if (errorCode != 0) {
return Health.down().withDetail("Error Code", errorCode).build()
}
return Health.up().build()
}
private fun check(): Int {
// perform some specific health check
return ...
}
}
The identifier for a given HealthIndicator is the name of the bean without the HealthIndicator suffix, if it exists.
In the preceding example, the health information is available in an entry named my .
|
Health indicators are usually called over HTTP and need to respond before any connection timeouts.
Spring Boot will log a warning message for any health indicator that takes longer than 10 seconds to respond.
If you want to configure this threshold, you can use the management.endpoint.health.logging.slow-indicator-threshold property.
|
In addition to Spring Boot’s predefined Status
types, Health
can return a custom Status
that represents a new system state.
In such cases, you also need to provide a custom implementation of the StatusAggregator
interface, or you must configure the default implementation by using the management.endpoint.health.status.order
configuration property.
For example, assume a new Status
with a code of FATAL
is being used in one of your HealthIndicator
implementations.
To configure the severity order, add the following property to your application properties:
management.endpoint.health.status.order=fatal,down,out-of-service,unknown,up
management:
endpoint:
health:
status:
order: "fatal,down,out-of-service,unknown,up"
The HTTP status code in the response reflects the overall health status.
By default, OUT_OF_SERVICE
and DOWN
map to 503.
Any unmapped health statuses, including UP
, map to 200.
You might also want to register custom status mappings if you access the health endpoint over HTTP.
Configuring a custom mapping disables the defaults mappings for DOWN
and OUT_OF_SERVICE
.
If you want to retain the default mappings, you must explicitly configure them, alongside any custom mappings.
For example, the following property maps FATAL
to 503 (service unavailable) and retains the default mappings for DOWN
and OUT_OF_SERVICE
:
management.endpoint.health.status.http-mapping.down=503
management.endpoint.health.status.http-mapping.fatal=503
management.endpoint.health.status.http-mapping.out-of-service=503
management:
endpoint:
health:
status:
http-mapping:
down: 503
fatal: 503
out-of-service: 503
If you need more control, you can define your own HttpCodeStatusMapper bean.
|
The following table shows the default status mappings for the built-in statuses:
Status | Mapping |
---|---|
|
|
|
|
|
No mapping by default, so HTTP status is |
|
No mapping by default, so HTTP status is |
Reactive Health Indicators
For reactive applications, such as those that use Spring WebFlux, ReactiveHealthContributor
provides a non-blocking contract for getting application health.
Similar to a traditional HealthContributor
, health information is collected from the content of a ReactiveHealthContributorRegistry
(by default, all HealthContributor
and ReactiveHealthContributor
instances defined in your ApplicationContext
).
Regular HealthContributors
that do not check against a reactive API are executed on the elastic scheduler.
In a reactive application, you should use the ReactiveHealthContributorRegistry to register and unregister health indicators at runtime.
If you need to register a regular HealthContributor , you should wrap it with ReactiveHealthContributor#adapt .
|
To provide custom health information from a reactive API, you can register Spring beans that implement the ReactiveHealthIndicator
interface.
The following code shows a sample ReactiveHealthIndicator
implementation:
@Component
public class MyReactiveHealthIndicator implements ReactiveHealthIndicator {
@Override
public Mono<Health> health() {
return doHealthCheck().onErrorResume((exception) ->
Mono.just(new Health.Builder().down(exception).build()));
}
private Mono<Health> doHealthCheck() {
// perform some specific health check
return ...
}
}
@Component
class MyReactiveHealthIndicator : ReactiveHealthIndicator {
override fun health(): Mono<Health> {
return doHealthCheck()!!.onErrorResume { exception: Throwable? ->
Mono.just(Health.Builder().down(exception).build())
}
}
private fun doHealthCheck(): Mono<Health>? {
// perform some specific health check
return ...
}
}
To handle the error automatically, consider extending from AbstractReactiveHealthIndicator .
|
Auto-configured ReactiveHealthIndicators
When appropriate, Spring Boot auto-configures the following ReactiveHealthIndicators
:
Key | Name | Description |
---|---|---|
|
Checks that a Cassandra database is up. |
|
|
Checks that a Couchbase cluster is up. |
|
|
Checks that an Elasticsearch cluster is up. |
|
|
Checks that a Mongo database is up. |
|
|
Checks that a Neo4j database is up. |
|
|
Checks that a Redis server is up. |
If necessary, reactive indicators replace the regular ones.
Also, any HealthIndicator that is not handled explicitly is wrapped automatically.
|
Health Groups
It is sometimes useful to organize health indicators into groups that you can use for different purposes.
To create a health indicator group, you can use the management.endpoint.health.group.<name>
property and specify a list of health indicator IDs to include
or exclude
.
For example, to create a group that includes only database indicators you can define the following:
management.endpoint.health.group.custom.include=db
management:
endpoint:
health:
group:
custom:
include: "db"
You can then check the result by hitting localhost:8080/actuator/health/custom
.
Similarly, to create a group that excludes the database indicators from the group and includes all the other indicators, you can define the following:
management.endpoint.health.group.custom.exclude=db
management:
endpoint:
health:
group:
custom:
exclude: "db"
By default, startup will fail if a health group includes or excludes a health indicator that does not exist.
To disable this behavior set management.endpoint.health.validate-group-membership
to false
.
By default, groups inherit the same StatusAggregator
and HttpCodeStatusMapper
settings as the system health.
However, you can also define these on a per-group basis.
You can also override the show-details
and roles
properties if required:
management.endpoint.health.group.custom.show-details=when-authorized
management.endpoint.health.group.custom.roles=admin
management.endpoint.health.group.custom.status.order=fatal,up
management.endpoint.health.group.custom.status.http-mapping.fatal=500
management.endpoint.health.group.custom.status.http-mapping.out-of-service=500
management:
endpoint:
health:
group:
custom:
show-details: "when-authorized"
roles: "admin"
status:
order: "fatal,up"
http-mapping:
fatal: 500
out-of-service: 500
You can use @Qualifier("groupname") if you need to register custom StatusAggregator or HttpCodeStatusMapper beans for use with the group.
|
A health group can also include/exclude a CompositeHealthContributor
.
You can also include/exclude only a certain component of a CompositeHealthContributor
.
This can be done using the fully qualified name of the component as follows:
management.endpoint.health.group.custom.include="test/primary"
management.endpoint.health.group.custom.exclude="test/primary/b"
In the example above, the custom
group will include the HealthContributor
with the name primary
which is a component of the composite test
.
Here, primary
itself is a composite and the HealthContributor
with the name b
will be excluded from the custom
group.
Health groups can be made available at an additional path on either the main or management port. This is useful in cloud environments such as Kubernetes, where it is quite common to use a separate management port for the actuator endpoints for security purposes. Having a separate port could lead to unreliable health checks because the main application might not work properly even if the health check is successful. The health group can be configured with an additional path as follows:
management.endpoint.health.group.live.additional-path="server:/healthz"
This would make the live
health group available on the main server port at /healthz
.
The prefix is mandatory and must be either server:
(represents the main server port) or management:
(represents the management port, if configured.)
The path must be a single path segment.
DataSource Health
The DataSource
health indicator shows the health of both standard data sources and routing data source beans.
The health of a routing data source includes the health of each of its target data sources.
In the health endpoint’s response, each of a routing data source’s targets is named by using its routing key.
If you prefer not to include routing data sources in the indicator’s output, set management.health.db.ignore-routing-data-sources
to true
.
13.2.10. Kubernetes Probes
Applications deployed on Kubernetes can provide information about their internal state with Container Probes. Depending on your Kubernetes configuration, the kubelet calls those probes and reacts to the result.
By default, Spring Boot manages your Application Availability State.
If deployed in a Kubernetes environment, actuator gathers the “Liveness” and “Readiness” information from the ApplicationAvailability
interface and uses that information in dedicated health indicators: LivenessStateHealthIndicator
and ReadinessStateHealthIndicator
.
These indicators are shown on the global health endpoint ("/actuator/health"
).
They are also exposed as separate HTTP Probes by using health groups: "/actuator/health/liveness"
and "/actuator/health/readiness"
.
You can then configure your Kubernetes infrastructure with the following endpoint information:
livenessProbe:
httpGet:
path: "/actuator/health/liveness"
port: <actuator-port>
failureThreshold: ...
periodSeconds: ...
readinessProbe:
httpGet:
path: "/actuator/health/readiness"
port: <actuator-port>
failureThreshold: ...
periodSeconds: ...
<actuator-port> should be set to the port that the actuator endpoints are available on.
It could be the main web server port or a separate management port if the "management.server.port" property has been set.
|
These health groups are automatically enabled only if the application runs in a Kubernetes environment.
You can enable them in any environment by using the management.endpoint.health.probes.enabled
configuration property.
If an application takes longer to start than the configured liveness period, Kubernetes mentions the "startupProbe" as a possible solution.
Generally speaking, the "startupProbe" is not necessarily needed here, as the "readinessProbe" fails until all startup tasks are done.
This means your application will not receive traffic until it is ready.
However, if your application takes a long time to start, consider using a "startupProbe" to make sure that Kubernetes won’t kill your application while it is in the process of starting.
See the section that describes how probes behave during the application lifecycle.
|
If your Actuator endpoints are deployed on a separate management context, the endpoints do not use the same web infrastructure (port, connection pools, framework components) as the main application.
In this case, a probe check could be successful even if the main application does not work properly (for example, it cannot accept new connections).
For this reason, is it a good idea to make the liveness
and readiness
health groups available on the main server port.
This can be done by setting the following property:
management.endpoint.health.probes.add-additional-paths=true
This would make the liveness
group available at /livez
and the readiness
group available at /readyz
on the main server port.
Paths can be customized using the additional-path
property on each group, see health groups for details.
Checking External State With Kubernetes Probes
Actuator configures the “liveness” and “readiness” probes as Health Groups. This means that all the health groups features are available for them. You can, for example, configure additional Health Indicators:
management.endpoint.health.group.readiness.include=readinessState,customCheck
management:
endpoint:
health:
group:
readiness:
include: "readinessState,customCheck"
By default, Spring Boot does not add other health indicators to these groups.
The “liveness” probe should not depend on health checks for external systems. If the liveness state of an application is broken, Kubernetes tries to solve that problem by restarting the application instance. This means that if an external system (such as a database, a Web API, or an external cache) fails, Kubernetes might restart all application instances and create cascading failures.
As for the “readiness” probe, the choice of checking external systems must be made carefully by the application developers. For this reason, Spring Boot does not include any additional health checks in the readiness probe. If the readiness state of an application instance is unready, Kubernetes does not route traffic to that instance. Some external systems might not be shared by application instances, in which case they could be included in a readiness probe. Other external systems might not be essential to the application (the application could have circuit breakers and fallbacks), in which case they definitely should not be included. Unfortunately, an external system that is shared by all application instances is common, and you have to make a judgement call: Include it in the readiness probe and expect that the application is taken out of service when the external service is down or leave it out and deal with failures higher up the stack, perhaps by using a circuit breaker in the caller.
If all instances of an application are unready, a Kubernetes Service with type=ClusterIP or NodePort does not accept any incoming connections.
There is no HTTP error response (503 and so on), since there is no connection.
A service with type=LoadBalancer might or might not accept connections, depending on the provider.
A service that has an explicit ingress also responds in a way that depends on the implementation — the ingress service itself has to decide how to handle the “connection refused” from downstream.
HTTP 503 is quite likely in the case of both load balancer and ingress.
|
Also, if an application uses Kubernetes autoscaling, it may react differently to applications being taken out of the load-balancer, depending on its autoscaler configuration.
Application Lifecycle and Probe States
An important aspect of the Kubernetes Probes support is its consistency with the application lifecycle.
There is a significant difference between the AvailabilityState
(which is the in-memory, internal state of the application)
and the actual probe (which exposes that state).
Depending on the phase of application lifecycle, the probe might not be available.
Spring Boot publishes application events during startup and shutdown,
and probes can listen to such events and expose the AvailabilityState
information.
The following tables show the AvailabilityState
and the state of HTTP connectors at different stages.
When a Spring Boot application starts:
Startup phase | LivenessState | ReadinessState | HTTP server | Notes |
---|---|---|---|---|
Starting |
|
|
Not started |
Kubernetes checks the "liveness" Probe and restarts the application if it takes too long. |
Started |
|
|
Refuses requests |
The application context is refreshed. The application performs startup tasks and does not receive traffic yet. |
Ready |
|
|
Accepts requests |
Startup tasks are finished. The application is receiving traffic. |
When a Spring Boot application shuts down:
Shutdown phase | Liveness State | Readiness State | HTTP server | Notes |
---|---|---|---|---|
Running |
|
|
Accepts requests |
Shutdown has been requested. |
Graceful shutdown |
|
|
New requests are rejected |
If enabled, graceful shutdown processes in-flight requests. |
Shutdown complete |
N/A |
N/A |
Server is shut down |
The application context is closed and the application is shut down. |
See Kubernetes container lifecycle section for more information about Kubernetes deployment. |
13.2.11. Application Information
Application information exposes various information collected from all InfoContributor
beans defined in your ApplicationContext
.
Spring Boot includes a number of auto-configured InfoContributor
beans, and you can write your own.
Auto-configured InfoContributors
When appropriate, Spring auto-configures the following InfoContributor
beans:
ID | Name | Description | Prerequisites |
---|---|---|---|
|
Exposes build information. |
A |
|
|
Exposes any property from the |
None. |
|
|
Exposes git information. |
A |
|
|
Exposes Java runtime information. |
None. |
|
|
Exposes Operating System information. |
None. |
Whether an individual contributor is enabled is controlled by its management.info.<id>.enabled
property.
Different contributors have different defaults for this property, depending on their prerequisites and the nature of the information that they expose.
With no prerequisites to indicate that they should be enabled, the env
, java
, and os
contributors are disabled by default.
Each can be enabled by setting its management.info.<id>.enabled
property to true
.
The build
and git
info contributors are enabled by default.
Each can be disabled by setting its management.info.<id>.enabled
property to false
.
Alternatively, to disable every contributor that is usually enabled by default, set the management.info.defaults.enabled
property to false
.
Custom Application Information
When the env
contributor is enabled, you can customize the data exposed by the info
endpoint by setting info.*
Spring properties.
All Environment
properties under the info
key are automatically exposed.
For example, you could add the following settings to your application.properties
file:
info.app.encoding=UTF-8
info.app.java.source=17
info.app.java.target=17
info:
app:
encoding: "UTF-8"
java:
source: "17"
target: "17"
Rather than hardcoding those values, you could also expand info properties at build time. Assuming you use Maven, you could rewrite the preceding example as follows: Properties
Yaml
|
Git Commit Information
Another useful feature of the info
endpoint is its ability to publish information about the state of your git
source code repository when the project was built.
If a GitProperties
bean is available, you can use the info
endpoint to expose these properties.
A GitProperties bean is auto-configured if a git.properties file is available at the root of the classpath.
See "how to generate git information" for more detail.
|
By default, the endpoint exposes git.branch
, git.commit.id
, and git.commit.time
properties, if present.
If you do not want any of these properties in the endpoint response, they need to be excluded from the git.properties
file.
If you want to display the full git information (that is, the full content of git.properties
), use the management.info.git.mode
property, as follows:
management.info.git.mode=full
management:
info:
git:
mode: "full"
To disable the git commit information from the info
endpoint completely, set the management.info.git.enabled
property to false
, as follows:
management.info.git.enabled=false
management:
info:
git:
enabled: false
Build Information
If a BuildProperties
bean is available, the info
endpoint can also publish information about your build.
This happens if a META-INF/build-info.properties
file is available in the classpath.
The Maven and Gradle plugins can both generate that file. See "how to generate build information" for more details. |
Java Information
The info
endpoint publishes information about your Java runtime environment, see JavaInfo
for more details.
OS Information
The info
endpoint publishes information about your Operating System, see OsInfo
for more details.
Writing Custom InfoContributors
To provide custom application information, you can register Spring beans that implement the InfoContributor
interface.
The following example contributes an example
entry with a single value:
@Component
public class MyInfoContributor implements InfoContributor {
@Override
public void contribute(Info.Builder builder) {
builder.withDetail("example", Collections.singletonMap("key", "value"));
}
}
@Component
class MyInfoContributor : InfoContributor {
override fun contribute(builder: Info.Builder) {
builder.withDetail("example", Collections.singletonMap("key", "value"))
}
}
If you reach the info
endpoint, you should see a response that contains the following additional entry:
{
"example": {
"key" : "value"
}
}
13.3. Monitoring and Management Over HTTP
If you are developing a web application, Spring Boot Actuator auto-configures all enabled endpoints to be exposed over HTTP.
The default convention is to use the id
of the endpoint with a prefix of /actuator
as the URL path.
For example, health
is exposed as /actuator/health
.
Actuator is supported natively with Spring MVC, Spring WebFlux, and Jersey. If both Jersey and Spring MVC are available, Spring MVC is used. |
Jackson is a required dependency in order to get the correct JSON responses as documented in the API documentation (HTML or PDF). |
13.3.1. Customizing the Management Endpoint Paths
Sometimes, it is useful to customize the prefix for the management endpoints.
For example, your application might already use /actuator
for another purpose.
You can use the management.endpoints.web.base-path
property to change the prefix for your management endpoint, as the following example shows:
management.endpoints.web.base-path=/manage
management:
endpoints:
web:
base-path: "/manage"
The preceding application.properties
example changes the endpoint from /actuator/{id}
to /manage/{id}
(for example, /manage/info
).
Unless the management port has been configured to expose endpoints by using a different HTTP port, management.endpoints.web.base-path is relative to server.servlet.context-path (for servlet web applications) or spring.webflux.base-path (for reactive web applications).
If management.server.port is configured, management.endpoints.web.base-path is relative to management.server.base-path .
|
If you want to map endpoints to a different path, you can use the management.endpoints.web.path-mapping
property.
The following example remaps /actuator/health
to /healthcheck
:
management.endpoints.web.base-path=/
management.endpoints.web.path-mapping.health=healthcheck
management:
endpoints:
web:
base-path: "/"
path-mapping:
health: "healthcheck"
13.3.2. Customizing the Management Server Port
Exposing management endpoints by using the default HTTP port is a sensible choice for cloud-based deployments. If, however, your application runs inside your own data center, you may prefer to expose endpoints by using a different HTTP port.
You can set the management.server.port
property to change the HTTP port, as the following example shows:
management.server.port=8081
management:
server:
port: 8081
On Cloud Foundry, by default, applications receive requests only on port 8080 for both HTTP and TCP routing. If you want to use a custom management port on Cloud Foundry, you need to explicitly set up the application’s routes to forward traffic to the custom port. |
13.3.3. Configuring Management-specific SSL
When configured to use a custom port, you can also configure the management server with its own SSL by using the various management.server.ssl.*
properties.
For example, doing so lets a management server be available over HTTP while the main application uses HTTPS, as the following property settings show:
server.port=8443
server.ssl.enabled=true
server.ssl.key-store=classpath:store.jks
server.ssl.key-password=secret
management.server.port=8080
management.server.ssl.enabled=false
server:
port: 8443
ssl:
enabled: true
key-store: "classpath:store.jks"
key-password: "secret"
management:
server:
port: 8080
ssl:
enabled: false
Alternatively, both the main server and the management server can use SSL but with different key stores, as follows:
server.port=8443
server.ssl.enabled=true
server.ssl.key-store=classpath:main.jks
server.ssl.key-password=secret
management.server.port=8080
management.server.ssl.enabled=true
management.server.ssl.key-store=classpath:management.jks
management.server.ssl.key-password=secret
server:
port: 8443
ssl:
enabled: true
key-store: "classpath:main.jks"
key-password: "secret"
management:
server:
port: 8080
ssl:
enabled: true
key-store: "classpath:management.jks"
key-password: "secret"
13.3.4. Customizing the Management Server Address
You can customize the address on which the management endpoints are available by setting the management.server.address
property.
Doing so can be useful if you want to listen only on an internal or ops-facing network or to listen only for connections from localhost
.
You can listen on a different address only when the port differs from the main server port. |
The following example application.properties
does not allow remote management connections:
management.server.port=8081
management.server.address=127.0.0.1
management:
server:
port: 8081
address: "127.0.0.1"
13.3.5. Disabling HTTP Endpoints
If you do not want to expose endpoints over HTTP, you can set the management port to -1
, as the following example shows:
management.server.port=-1
management:
server:
port: -1
You can also achieve this by using the management.endpoints.web.exposure.exclude
property, as the following example shows:
management.endpoints.web.exposure.exclude=*
management:
endpoints:
web:
exposure:
exclude: "*"
13.4. Monitoring and Management over JMX
Java Management Extensions (JMX) provide a standard mechanism to monitor and manage applications.
By default, this feature is not enabled.
You can turn it on by setting the spring.jmx.enabled
configuration property to true
.
Spring Boot exposes the most suitable MBeanServer
as a bean with an ID of mbeanServer
.
Any of your beans that are annotated with Spring JMX annotations (@ManagedResource
, @ManagedAttribute
, or @ManagedOperation
) are exposed to it.
If your platform provides a standard MBeanServer
, Spring Boot uses that and defaults to the VM MBeanServer
, if necessary.
If all that fails, a new MBeanServer
is created.
See the JmxAutoConfiguration
class for more details.
By default, Spring Boot also exposes management endpoints as JMX MBeans under the org.springframework.boot
domain.
To take full control over endpoint registration in the JMX domain, consider registering your own EndpointObjectNameFactory
implementation.
13.4.1. Customizing MBean Names
The name of the MBean is usually generated from the id
of the endpoint.
For example, the health
endpoint is exposed as org.springframework.boot:type=Endpoint,name=Health
.
If your application contains more than one Spring ApplicationContext
, you may find that names clash.
To solve this problem, you can set the spring.jmx.unique-names
property to true
so that MBean names are always unique.
You can also customize the JMX domain under which endpoints are exposed.
The following settings show an example of doing so in application.properties
:
spring.jmx.unique-names=true
management.endpoints.jmx.domain=com.example.myapp
spring:
jmx:
unique-names: true
management:
endpoints:
jmx:
domain: "com.example.myapp"
13.5. Observability
Observability is the ability to observe the internal state of a running system from the outside. It consists of the three pillars logging, metrics and traces.
For metrics and traces, Spring Boot uses Micrometer Observation.
To create your own observations (which will lead to metrics and traces), you can inject an ObservationRegistry
.
@Component
public class MyCustomObservation {
private final ObservationRegistry observationRegistry;
public MyCustomObservation(ObservationRegistry observationRegistry) {
this.observationRegistry = observationRegistry;
}
public void doSomething() {
Observation.createNotStarted("doSomething", this.observationRegistry)
.lowCardinalityKeyValue("locale", "en-US")
.highCardinalityKeyValue("userId", "42")
.observe(() -> {
// Execute business logic here
});
}
}
Low cardinality key-values will be added to metrics and traces, while high cardinality key-values will only be added to traces. |
Beans of type ObservationPredicate
, GlobalObservationConvention
, ObservationFilter
and ObservationHandler
will be automatically registered on the ObservationRegistry
.
You can additionally register any number of ObservationRegistryCustomizer
beans to further configure the registry.
Observability support relies on the Context Propagation library for forwarding the current observation across threads and reactive pipelines.
By default, ThreadLocal
values are not automatically reinstated in reactive operators.
This behavior is controlled with the spring.reactor.context-propagation
property, which can be set to auto
to enable automatic propagation.
For more details about observations please see the Micrometer Observation documentation.
Observability for JDBC can be configured using a separate project. The Datasource Micrometer project provides a Spring Boot starter which automatically creates observations when JDBC operations are invoked. Read more about it in the reference documentation. |
Observability for R2DBC is built into Spring Boot.
To enable it, add the io.r2dbc:r2dbc-proxy dependency to your project.
|
13.5.1. Common Key-Values
Common key-values are generally used for dimensional drill-down on the operating environment, such as host, instance, region, stack, and others. Common key-values are applied to all observations as low cardinality key-values and can be configured, as the following example shows:
management.observations.key-values.region=us-east-1
management.observations.key-values.stack=prod
management:
observations:
key-values:
region: "us-east-1"
stack: "prod"
The preceding example adds region
and stack
key-values to all observations with a value of us-east-1
and prod
, respectively.
13.5.2. Preventing Observations
If you’d like to prevent some observations from being reported, you can use the management.observations.enable
properties:
management.observations.enable.denied.prefix=false
management.observations.enable.another.denied.prefix=false
management:
observations:
enable:
denied:
prefix: false
another:
denied:
prefix: false
The preceding example will prevent all observations with a name starting with denied.prefix
or another.denied.prefix
.
If you want to prevent Spring Security from reporting observations, set the property management.observations.enable.spring.security to false .
|
If you need greater control over the prevention of observations, you can register beans of type ObservationPredicate
.
Observations are only reported if all the ObservationPredicate
beans return true
for that observation.
@Component
class MyObservationPredicate implements ObservationPredicate {
@Override
public boolean test(String name, Context context) {
return !name.contains("denied");
}
}
The preceding example will prevent all observations whose name contains "denied".
13.5.3. OpenTelemetry Support
Spring Boot’s actuator module includes basic support for OpenTelemetry.
It provides a bean of type OpenTelemetry
, and if there are beans of type SdkTracerProvider
, ContextPropagators
, SdkLoggerProvider
or SdkMeterProvider
in the application context, they automatically get registered.
Additionally, it provides a Resource
bean.
The attributes of the Resource
can be configured via the management.opentelemetry.resource-attributes
configuration property.
Spring Boot does not provide auto-configuration for OpenTelemetry metrics or logging. OpenTelemetry tracing is only auto-configured when used together with Micrometer Tracing. |
The next sections will provide more details about logging, metrics and traces.
13.6. Loggers
Spring Boot Actuator includes the ability to view and configure the log levels of your application at runtime. You can view either the entire list or an individual logger’s configuration, which is made up of both the explicitly configured logging level as well as the effective logging level given to it by the logging framework. These levels can be one of:
-
TRACE
-
DEBUG
-
INFO
-
WARN
-
ERROR
-
FATAL
-
OFF
-
null
null
indicates that there is no explicit configuration.
13.6.1. Configure a Logger
To configure a given logger, POST
a partial entity to the resource’s URI, as the following example shows:
{
"configuredLevel": "DEBUG"
}
To “reset” the specific level of the logger (and use the default configuration instead), you can pass a value of null as the configuredLevel .
|
13.7. Metrics
Spring Boot Actuator provides dependency management and auto-configuration for Micrometer, an application metrics facade that supports numerous monitoring systems, including:
To learn more about Micrometer’s capabilities, see its reference documentation, in particular the concepts section. |
13.7.1. Getting started
Spring Boot auto-configures a composite MeterRegistry
and adds a registry to the composite for each of the supported implementations that it finds on the classpath.
Having a dependency on micrometer-registry-{system}
in your runtime classpath is enough for Spring Boot to configure the registry.
Most registries share common features. For instance, you can disable a particular registry even if the Micrometer registry implementation is on the classpath. The following example disables Datadog:
management.datadog.metrics.export.enabled=false
management:
datadog:
metrics:
export:
enabled: false
You can also disable all registries unless stated otherwise by the registry-specific property, as the following example shows:
management.defaults.metrics.export.enabled=false
management:
defaults:
metrics:
export:
enabled: false
Spring Boot also adds any auto-configured registries to the global static composite registry on the Metrics
class, unless you explicitly tell it not to:
management.metrics.use-global-registry=false
management:
metrics:
use-global-registry: false
You can register any number of MeterRegistryCustomizer
beans to further configure the registry, such as applying common tags, before any meters are registered with the registry:
@Configuration(proxyBeanMethods = false)
public class MyMeterRegistryConfiguration {
@Bean
public MeterRegistryCustomizer<MeterRegistry> metricsCommonTags() {
return (registry) -> registry.config().commonTags("region", "us-east-1");
}
}
@Configuration(proxyBeanMethods = false)
class MyMeterRegistryConfiguration {
@Bean
fun metricsCommonTags(): MeterRegistryCustomizer<MeterRegistry> {
return MeterRegistryCustomizer { registry ->
registry.config().commonTags("region", "us-east-1")
}
}
}
You can apply customizations to particular registry implementations by being more specific about the generic type:
@Configuration(proxyBeanMethods = false)
public class MyMeterRegistryConfiguration {
@Bean
public MeterRegistryCustomizer<GraphiteMeterRegistry> graphiteMetricsNamingConvention() {
return (registry) -> registry.config().namingConvention(this::name);
}
private String name(String name, Meter.Type type, String baseUnit) {
return ...
}
}
@Configuration(proxyBeanMethods = false)
class MyMeterRegistryConfiguration {
@Bean
fun graphiteMetricsNamingConvention(): MeterRegistryCustomizer<GraphiteMeterRegistry> {
return MeterRegistryCustomizer { registry: GraphiteMeterRegistry ->
registry.config().namingConvention(this::name)
}
}
private fun name(name: String, type: Meter.Type, baseUnit: String?): String {
return ...
}
}
Spring Boot also configures built-in instrumentation that you can control through configuration or dedicated annotation markers.
13.7.2. Supported Monitoring Systems
This section briefly describes each of the supported monitoring systems.
AppOptics
By default, the AppOptics registry periodically pushes metrics to api.appoptics.com/v1/measurements
.
To export metrics to SaaS AppOptics, your API token must be provided:
management.appoptics.metrics.export.api-token=YOUR_TOKEN
management:
appoptics:
metrics:
export:
api-token: "YOUR_TOKEN"
Atlas
By default, metrics are exported to Atlas running on your local machine. You can provide the location of the Atlas server:
management.atlas.metrics.export.uri=https://atlas.example.com:7101/api/v1/publish
management:
atlas:
metrics:
export:
uri: "https://atlas.example.com:7101/api/v1/publish"
Datadog
A Datadog registry periodically pushes metrics to datadoghq. To export metrics to Datadog, you must provide your API key:
management.datadog.metrics.export.api-key=YOUR_KEY
management:
datadog:
metrics:
export:
api-key: "YOUR_KEY"
If you additionally provide an application key (optional), then metadata such as meter descriptions, types, and base units will also be exported:
management.datadog.metrics.export.api-key=YOUR_API_KEY
management.datadog.metrics.export.application-key=YOUR_APPLICATION_KEY
management:
datadog:
metrics:
export:
api-key: "YOUR_API_KEY"
application-key: "YOUR_APPLICATION_KEY"
By default, metrics are sent to the Datadog US site (api.datadoghq.com
).
If your Datadog project is hosted on one of the other sites, or you need to send metrics through a proxy, configure the URI accordingly:
management.datadog.metrics.export.uri=https://api.datadoghq.eu
management:
datadog:
metrics:
export:
uri: "https://api.datadoghq.eu"
You can also change the interval at which metrics are sent to Datadog:
management.datadog.metrics.export.step=30s
management:
datadog:
metrics:
export:
step: "30s"
Dynatrace
Dynatrace offers two metrics ingest APIs, both of which are implemented for Micrometer.
You can find the Dynatrace documentation on Micrometer metrics ingest here.
Configuration properties in the v1
namespace apply only when exporting to the Timeseries v1 API.
Configuration properties in the v2
namespace apply only when exporting to the Metrics v2 API.
Note that this integration can export only to either the v1
or v2
version of the API at a time, with v2
being preferred.
If the device-id
(required for v1 but not used in v2) is set in the v1
namespace, metrics are exported to the v1
endpoint.
Otherwise, v2
is assumed.
v2 API
You can use the v2 API in two ways.
Dynatrace auto-configuration is available for hosts that are monitored by the OneAgent or by the Dynatrace Operator for Kubernetes.
Local OneAgent: If a OneAgent is running on the host, metrics are automatically exported to the local OneAgent ingest endpoint. The ingest endpoint forwards the metrics to the Dynatrace backend.
Dynatrace Kubernetes Operator: When running in Kubernetes with the Dynatrace Operator installed, the registry will automatically pick up your endpoint URI and API token from the operator instead.
This is the default behavior and requires no special setup beyond a dependency on io.micrometer:micrometer-registry-dynatrace
.
If no auto-configuration is available, the endpoint of the Metrics v2 API and an API token are required.
The API token must have the “Ingest metrics” (metrics.ingest
) permission set.
We recommend limiting the scope of the token to this one permission.
You must ensure that the endpoint URI contains the path (for example, /api/v2/metrics/ingest
):
The URL of the Metrics API v2 ingest endpoint is different according to your deployment option:
-
SaaS:
https://{your-environment-id}.live.dynatrace.com/api/v2/metrics/ingest
-
Managed deployments:
https://{your-domain}/e/{your-environment-id}/api/v2/metrics/ingest
The example below configures metrics export using the example
environment id:
management.dynatrace.metrics.export.uri=https://example.live.dynatrace.com/api/v2/metrics/ingest
management.dynatrace.metrics.export.api-token=YOUR_TOKEN
management:
dynatrace:
metrics:
export:
uri: "https://example.live.dynatrace.com/api/v2/metrics/ingest"
api-token: "YOUR_TOKEN"
When using the Dynatrace v2 API, the following optional features are available (more details can be found in the Dynatrace documentation):
-
Metric key prefix: Sets a prefix that is prepended to all exported metric keys.
-
Enrich with Dynatrace metadata: If a OneAgent or Dynatrace operator is running, enrich metrics with additional metadata (for example, about the host, process, or pod).
-
Default dimensions: Specify key-value pairs that are added to all exported metrics. If tags with the same key are specified with Micrometer, they overwrite the default dimensions.
-
Use Dynatrace Summary instruments: In some cases the Micrometer Dynatrace registry created metrics that were rejected. In Micrometer 1.9.x, this was fixed by introducing Dynatrace-specific summary instruments. Setting this toggle to
false
forces Micrometer to fall back to the behavior that was the default before 1.9.x. It should only be used when encountering problems while migrating from Micrometer 1.8.x to 1.9.x. -
Export meter metadata: Starting from Micrometer 1.12.0, the Dynatrace exporter will also export meter metadata, such as unit and description by default. Use the
export-meter-metadata
toggle to turn this feature off.
It is possible to not specify a URI and API token, as shown in the following example. In this scenario, the automatically configured endpoint is used:
management.dynatrace.metrics.export.v2.metric-key-prefix=your.key.prefix
management.dynatrace.metrics.export.v2.enrich-with-dynatrace-metadata=true
management.dynatrace.metrics.export.v2.default-dimensions.key1=value1
management.dynatrace.metrics.export.v2.default-dimensions.key2=value2
management.dynatrace.metrics.export.v2.use-dynatrace-summary-instruments=true
management.dynatrace.metrics.export.v2.export-meter-metadata=true
management:
dynatrace:
metrics:
export:
# Specify uri and api-token here if not using the local OneAgent endpoint.
v2:
metric-key-prefix: "your.key.prefix"
enrich-with-dynatrace-metadata: true
default-dimensions:
key1: "value1"
key2: "value2"
use-dynatrace-summary-instruments: true # (default: true)
export-meter-metadata: true # (default: true)
v1 API (Legacy)
The Dynatrace v1 API metrics registry pushes metrics to the configured URI periodically by using the Timeseries v1 API.
For backwards-compatibility with existing setups, when device-id
is set (required for v1, but not used in v2), metrics are exported to the Timeseries v1 endpoint.
To export metrics to Dynatrace, your API token, device ID, and URI must be provided:
management.dynatrace.metrics.export.uri=https://{your-environment-id}.live.dynatrace.com
management.dynatrace.metrics.export.api-token=YOUR_TOKEN
management.dynatrace.metrics.export.v1.device-id=YOUR_DEVICE_ID
management:
dynatrace:
metrics:
export:
uri: "https://{your-environment-id}.live.dynatrace.com"
api-token: "YOUR_TOKEN"
v1:
device-id: "YOUR_DEVICE_ID"
For the v1 API, you must specify the base environment URI without a path, as the v1 endpoint path is added automatically.
Version-independent Settings
In addition to the API endpoint and token, you can also change the interval at which metrics are sent to Dynatrace.
The default export interval is 60s
.
The following example sets the export interval to 30 seconds:
management.dynatrace.metrics.export.step=30s
management:
dynatrace:
metrics:
export:
step: "30s"
You can find more information on how to set up the Dynatrace exporter for Micrometer in the Micrometer documentation and the Dynatrace documentation.
Elastic
By default, metrics are exported to Elastic running on your local machine. You can provide the location of the Elastic server to use by using the following property:
management.elastic.metrics.export.host=https://elastic.example.com:8086
management:
elastic:
metrics:
export:
host: "https://elastic.example.com:8086"
Ganglia
By default, metrics are exported to Ganglia running on your local machine. You can provide the Ganglia server host and port, as the following example shows:
management.ganglia.metrics.export.host=ganglia.example.com
management.ganglia.metrics.export.port=9649
management:
ganglia:
metrics:
export:
host: "ganglia.example.com"
port: 9649
Graphite
By default, metrics are exported to Graphite running on your local machine. You can provide the Graphite server host and port, as the following example shows:
management.graphite.metrics.export.host=graphite.example.com
management.graphite.metrics.export.port=9004
management:
graphite:
metrics:
export:
host: "graphite.example.com"
port: 9004
Micrometer provides a default HierarchicalNameMapper
that governs how a dimensional meter ID is mapped to flat hierarchical names.
To take control over this behavior, define your Java
Kotlin
|
Humio
By default, the Humio registry periodically pushes metrics to cloud.humio.com. To export metrics to SaaS Humio, you must provide your API token:
management.humio.metrics.export.api-token=YOUR_TOKEN
management:
humio:
metrics:
export:
api-token: "YOUR_TOKEN"
You should also configure one or more tags to identify the data source to which metrics are pushed:
management.humio.metrics.export.tags.alpha=a
management.humio.metrics.export.tags.bravo=b
management:
humio:
metrics:
export:
tags:
alpha: "a"
bravo: "b"
Influx
By default, metrics are exported to an Influx v1 instance running on your local machine with the default configuration.
To export metrics to InfluxDB v2, configure the org
, bucket
, and authentication token
for writing metrics.
You can provide the location of the Influx server to use by using:
management.influx.metrics.export.uri=https://influx.example.com:8086
management:
influx:
metrics:
export:
uri: "https://influx.example.com:8086"
JMX
Micrometer provides a hierarchical mapping to JMX, primarily as a cheap and portable way to view metrics locally.
By default, metrics are exported to the metrics
JMX domain.
You can provide the domain to use by using:
management.jmx.metrics.export.domain=com.example.app.metrics
management:
jmx:
metrics:
export:
domain: "com.example.app.metrics"
Micrometer provides a default HierarchicalNameMapper
that governs how a dimensional meter ID is mapped to flat hierarchical names.
To take control over this behavior, define your Java
Kotlin
|
KairosDB
By default, metrics are exported to KairosDB running on your local machine. You can provide the location of the KairosDB server to use by using:
management.kairos.metrics.export.uri=https://kairosdb.example.com:8080/api/v1/datapoints
management:
kairos:
metrics:
export:
uri: "https://kairosdb.example.com:8080/api/v1/datapoints"
New Relic
A New Relic registry periodically pushes metrics to New Relic. To export metrics to New Relic, you must provide your API key and account ID:
management.newrelic.metrics.export.api-key=YOUR_KEY
management.newrelic.metrics.export.account-id=YOUR_ACCOUNT_ID
management:
newrelic:
metrics:
export:
api-key: "YOUR_KEY"
account-id: "YOUR_ACCOUNT_ID"
You can also change the interval at which metrics are sent to New Relic:
management.newrelic.metrics.export.step=30s
management:
newrelic:
metrics:
export:
step: "30s"
By default, metrics are published through REST calls, but you can also use the Java Agent API if you have it on the classpath:
management.newrelic.metrics.export.client-provider-type=insights-agent
management:
newrelic:
metrics:
export:
client-provider-type: "insights-agent"
Finally, you can take full control by defining your own NewRelicClientProvider
bean.
OpenTelemetry
By default, metrics are exported to OpenTelemetry running on your local machine. You can provide the location of the OpenTelemetry metric endpoint to use by using:
management.otlp.metrics.export.url=https://otlp.example.com:4318/v1/metrics
management:
otlp:
metrics:
export:
url: "https://otlp.example.com:4318/v1/metrics"
Prometheus
Prometheus expects to scrape or poll individual application instances for metrics.
Spring Boot provides an actuator endpoint at /actuator/prometheus
to present a Prometheus scrape with the appropriate format.
By default, the endpoint is not available and must be exposed. See exposing endpoints for more details. |
The following example scrape_config
adds to prometheus.yml
:
scrape_configs:
- job_name: "spring"
metrics_path: "/actuator/prometheus"
static_configs:
- targets: ["HOST:PORT"]
Prometheus Exemplars are also supported.
To enable this feature, a SpanContextSupplier
bean should be present.
If you use Micrometer Tracing, this will be auto-configured for you, but you can always create your own if you want.
Please check the Prometheus Docs, since this feature needs to be explicitly enabled on Prometheus' side, and it is only supported using the OpenMetrics format.
For ephemeral or batch jobs that may not exist long enough to be scraped, you can use Prometheus Pushgateway support to expose the metrics to Prometheus. To enable Prometheus Pushgateway support, add the following dependency to your project:
<dependency>
<groupId>io.prometheus</groupId>
<artifactId>simpleclient_pushgateway</artifactId>
</dependency>
When the Prometheus Pushgateway dependency is present on the classpath and the management.prometheus.metrics.export.pushgateway.enabled
property is set to true
, a PrometheusPushGatewayManager
bean is auto-configured.
This manages the pushing of metrics to a Prometheus Pushgateway.
You can tune the PrometheusPushGatewayManager
by using properties under management.prometheus.metrics.export.pushgateway
.
For advanced configuration, you can also provide your own PrometheusPushGatewayManager
bean.
SignalFx
SignalFx registry periodically pushes metrics to SignalFx. To export metrics to SignalFx, you must provide your access token:
management.signalfx.metrics.export.access-token=YOUR_ACCESS_TOKEN
management:
signalfx:
metrics:
export:
access-token: "YOUR_ACCESS_TOKEN"
You can also change the interval at which metrics are sent to SignalFx:
management.signalfx.metrics.export.step=30s
management:
signalfx:
metrics:
export:
step: "30s"
Simple
Micrometer ships with a simple, in-memory backend that is automatically used as a fallback if no other registry is configured. This lets you see what metrics are collected in the metrics endpoint.
The in-memory backend disables itself as soon as you use any other available backend. You can also disable it explicitly:
management.simple.metrics.export.enabled=false
management:
simple:
metrics:
export:
enabled: false
Stackdriver
The Stackdriver registry periodically pushes metrics to Stackdriver. To export metrics to SaaS Stackdriver, you must provide your Google Cloud project ID:
management.stackdriver.metrics.export.project-id=my-project
management:
stackdriver:
metrics:
export:
project-id: "my-project"
You can also change the interval at which metrics are sent to Stackdriver:
management.stackdriver.metrics.export.step=30s
management:
stackdriver:
metrics:
export:
step: "30s"
StatsD
The StatsD registry eagerly pushes metrics over UDP to a StatsD agent. By default, metrics are exported to a StatsD agent running on your local machine. You can provide the StatsD agent host, port, and protocol to use by using:
management.statsd.metrics.export.host=statsd.example.com
management.statsd.metrics.export.port=9125
management.statsd.metrics.export.protocol=udp
management:
statsd:
metrics:
export:
host: "statsd.example.com"
port: 9125
protocol: "udp"
You can also change the StatsD line protocol to use (it defaults to Datadog):
management.statsd.metrics.export.flavor=etsy
management:
statsd:
metrics:
export:
flavor: "etsy"
Wavefront
The Wavefront registry periodically pushes metrics to Wavefront. If you are exporting metrics to Wavefront directly, you must provide your API token:
management.wavefront.api-token=YOUR_API_TOKEN
management:
wavefront:
api-token: "YOUR_API_TOKEN"
Alternatively, you can use a Wavefront sidecar or an internal proxy in your environment to forward metrics data to the Wavefront API host:
management.wavefront.uri=proxy://localhost:2878
management:
wavefront:
uri: "proxy://localhost:2878"
If you publish metrics to a Wavefront proxy (as described in the Wavefront documentation), the host must be in the proxy://HOST:PORT format.
|
You can also change the interval at which metrics are sent to Wavefront:
management.wavefront.metrics.export.step=30s
management:
wavefront:
metrics:
export:
step: "30s"
13.7.3. Supported Metrics and Meters
Spring Boot provides automatic meter registration for a wide variety of technologies. In most situations, the defaults provide sensible metrics that can be published to any of the supported monitoring systems.
JVM Metrics
Auto-configuration enables JVM Metrics by using core Micrometer classes.
JVM metrics are published under the jvm.
meter name.
The following JVM metrics are provided:
-
Various memory and buffer pool details
-
Statistics related to garbage collection
-
Thread utilization
-
The number of classes loaded and unloaded
-
JVM version information
-
JIT compilation time
System Metrics
Auto-configuration enables system metrics by using core Micrometer classes.
System metrics are published under the system.
, process.
, and disk.
meter names.
The following system metrics are provided:
-
CPU metrics
-
File descriptor metrics
-
Uptime metrics (both the amount of time the application has been running and a fixed gauge of the absolute start time)
-
Disk space available
Application Startup Metrics
Auto-configuration exposes application startup time metrics:
-
application.started.time
: time taken to start the application. -
application.ready.time
: time taken for the application to be ready to service requests.
Metrics are tagged by the fully qualified name of the application class.
Logger Metrics
Auto-configuration enables the event metrics for both Logback and Log4J2.
The details are published under the log4j2.events.
or logback.events.
meter names.
Task Execution and Scheduling Metrics
Auto-configuration enables the instrumentation of all available ThreadPoolTaskExecutor
and ThreadPoolTaskScheduler
beans, as long as the underling ThreadPoolExecutor
is available.
Metrics are tagged by the name of the executor, which is derived from the bean name.
JMS Metrics
Auto-configuration enables the instrumentation of all available JmsTemplate
beans.
JmsMessagingTemplate
instances built with instrumented JmsTemplate
beans will also record observations.
See the Spring Framework reference documentation for more information on produced observations.
Spring MVC Metrics
Auto-configuration enables the instrumentation of all requests handled by Spring MVC controllers and functional handlers.
By default, metrics are generated with the name, http.server.requests
.
You can customize the name by setting the management.observations.http.server.requests.name
property.
To add to the default tags, provide a @Bean
that extends DefaultServerRequestObservationConvention
from the org.springframework.http.server.observation
package.
To replace the default tags, provide a @Bean
that implements ServerRequestObservationConvention
.
In some cases, exceptions handled in web controllers are not recorded as request metrics tags. Applications can opt in and record exceptions by setting handled exceptions as request attributes. |
By default, all requests are handled.
To customize the filter, provide a @Bean
that implements FilterRegistrationBean<WebMvcMetricsFilter>
.
Spring WebFlux Metrics
Auto-configuration enables the instrumentation of all requests handled by Spring WebFlux controllers and functional handlers.
By default, metrics are generated with the name, http.server.requests
.
You can customize the name by setting the management.observations.http.server.requests.name
property.
To add to the default tags, provide a @Bean
that extends DefaultServerRequestObservationConvention
from the org.springframework.http.server.reactive.observation
package.
To replace the default tags, provide a @Bean
that implements ServerRequestObservationConvention
.
In some cases, exceptions handled in controllers and handler functions are not recorded as request metrics tags. Applications can opt in and record exceptions by setting handled exceptions as request attributes. |
Jersey Server Metrics
Auto-configuration enables the instrumentation of all requests handled by the Jersey JAX-RS implementation.
By default, metrics are generated with the name, http.server.requests
.
You can customize the name by setting the management.observations.http.server.requests.name
property.
By default, Jersey server metrics are tagged with the following information:
Tag | Description |
---|---|
|
The simple class name of any exception that was thrown while handling the request. |
|
The request’s method (for example, |
|
The request’s outcome, based on the status code of the response.
1xx is |
|
The response’s HTTP status code (for example, |
|
The request’s URI template prior to variable substitution, if possible (for example, |
To customize the tags, provide a @Bean
that implements JerseyTagsProvider
.
HTTP Client Metrics
Spring Boot Actuator manages the instrumentation of RestTemplate
, WebClient
and RestClient
.
For that, you have to inject the auto-configured builder and use it to create instances:
-
RestTemplateBuilder
forRestTemplate
-
WebClient.Builder
forWebClient
-
RestClient.Builder
forRestClient
You can also manually apply the customizers responsible for this instrumentation, namely ObservationRestTemplateCustomizer
, ObservationWebClientCustomizer
and ObservationRestClientCustomizer
.
By default, metrics are generated with the name, http.client.requests
.
You can customize the name by setting the management.observations.http.client.requests.name
property.
To customize the tags when using RestTemplate
or RestClient
, provide a @Bean
that implements ClientRequestObservationConvention
from the org.springframework.http.client.observation
package.
To customize the tags when using WebClient
, provide a @Bean
that implements ClientRequestObservationConvention
from the org.springframework.web.reactive.function.client
package.
Tomcat Metrics
Auto-configuration enables the instrumentation of Tomcat only when an MBeanRegistry
is enabled.
By default, the MBeanRegistry
is disabled, but you can enable it by setting server.tomcat.mbeanregistry.enabled
to true
.
Tomcat metrics are published under the tomcat.
meter name.
Cache Metrics
Auto-configuration enables the instrumentation of all available Cache
instances on startup, with metrics prefixed with cache
.
Cache instrumentation is standardized for a basic set of metrics.
Additional, cache-specific metrics are also available.
The following cache libraries are supported:
-
Cache2k
-
Caffeine
-
Hazelcast
-
Any compliant JCache (JSR-107) implementation
-
Redis
Metrics are tagged by the name of the cache and by the name of the CacheManager
, which is derived from the bean name.
Only caches that are configured on startup are bound to the registry.
For caches not defined in the cache’s configuration, such as caches created on the fly or programmatically after the startup phase, an explicit registration is required.
A CacheMetricsRegistrar bean is made available to make that process easier.
|
Spring Batch Metrics
See the Spring Batch reference documentation.
DataSource Metrics
Auto-configuration enables the instrumentation of all available DataSource
objects with metrics prefixed with jdbc.connections
.
Data source instrumentation results in gauges that represent the currently active, idle, maximum allowed, and minimum allowed connections in the pool.
Metrics are also tagged by the name of the DataSource
computed based on the bean name.
By default, Spring Boot provides metadata for all supported data sources.
You can add additional DataSourcePoolMetadataProvider beans if your favorite data source is not supported.
See DataSourcePoolMetadataProvidersConfiguration for examples.
|
Also, Hikari-specific metrics are exposed with a hikaricp
prefix.
Each metric is tagged by the name of the pool (you can control it with spring.datasource.name
).
Hibernate Metrics
If org.hibernate.orm:hibernate-micrometer
is on the classpath, all available Hibernate EntityManagerFactory
instances that have statistics enabled are instrumented with a metric named hibernate
.
Metrics are also tagged by the name of the EntityManagerFactory
, which is derived from the bean name.
To enable statistics, the standard JPA property hibernate.generate_statistics
must be set to true
.
You can enable that on the auto-configured EntityManagerFactory
:
spring.jpa.properties[hibernate.generate_statistics]=true
spring:
jpa:
properties:
"[hibernate.generate_statistics]": true
Spring Data Repository Metrics
Auto-configuration enables the instrumentation of all Spring Data Repository
method invocations.
By default, metrics are generated with the name, spring.data.repository.invocations
.
You can customize the name by setting the management.metrics.data.repository.metric-name
property.
The @Timed
annotation from the io.micrometer.core.annotation
package is supported on Repository
interfaces and methods.
If you do not want to record metrics for all Repository
invocations, you can set management.metrics.data.repository.autotime.enabled
to false
and exclusively use @Timed
annotations instead.
A @Timed annotation with longTask = true enables a long task timer for the method.
Long task timers require a separate metric name and can be stacked with a short task timer.
|
By default, repository invocation related metrics are tagged with the following information:
Tag | Description |
---|---|
|
The simple class name of the source |
|
The name of the |
|
The result state ( |
|
The simple class name of any exception that was thrown from the invocation. |
To replace the default tags, provide a @Bean
that implements RepositoryTagsProvider
.
RabbitMQ Metrics
Auto-configuration enables the instrumentation of all available RabbitMQ connection factories with a metric named rabbitmq
.
Spring Integration Metrics
Spring Integration automatically provides Micrometer support whenever a MeterRegistry
bean is available.
Metrics are published under the spring.integration.
meter name.
Kafka Metrics
Auto-configuration registers a MicrometerConsumerListener
and MicrometerProducerListener
for the auto-configured consumer factory and producer factory, respectively.
It also registers a KafkaStreamsMicrometerListener
for StreamsBuilderFactoryBean
.
For more detail, see the Micrometer Native Metrics section of the Spring Kafka documentation.
MongoDB Metrics
This section briefly describes the available metrics for MongoDB.
MongoDB Command Metrics
Auto-configuration registers a MongoMetricsCommandListener
with the auto-configured MongoClient
.
A timer metric named mongodb.driver.commands
is created for each command issued to the underlying MongoDB driver.
Each metric is tagged with the following information by default:
Tag | Description |
---|---|
|
The name of the command issued. |
|
The identifier of the cluster to which the command was sent. |
|
The address of the server to which the command was sent. |
|
The outcome of the command ( |
To replace the default metric tags, define a MongoCommandTagsProvider
bean, as the following example shows:
@Configuration(proxyBeanMethods = false)
public class MyCommandTagsProviderConfiguration {
@Bean
public MongoCommandTagsProvider customCommandTagsProvider() {
return new CustomCommandTagsProvider();
}
}
@Configuration(proxyBeanMethods = false)
class MyCommandTagsProviderConfiguration {
@Bean
fun customCommandTagsProvider(): MongoCommandTagsProvider? {
return CustomCommandTagsProvider()
}
}
To disable the auto-configured command metrics, set the following property:
management.metrics.mongo.command.enabled=false
management:
metrics:
mongo:
command:
enabled: false
MongoDB Connection Pool Metrics
Auto-configuration registers a MongoMetricsConnectionPoolListener
with the auto-configured MongoClient
.
The following gauge metrics are created for the connection pool:
-
mongodb.driver.pool.size
reports the current size of the connection pool, including idle and and in-use members. -
mongodb.driver.pool.checkedout
reports the count of connections that are currently in use. -
mongodb.driver.pool.waitqueuesize
reports the current size of the wait queue for a connection from the pool.
Each metric is tagged with the following information by default:
Tag | Description |
---|---|
|
The identifier of the cluster to which the connection pool corresponds. |
|
The address of the server to which the connection pool corresponds. |
To replace the default metric tags, define a MongoConnectionPoolTagsProvider
bean:
@Configuration(proxyBeanMethods = false)
public class MyConnectionPoolTagsProviderConfiguration {
@Bean
public MongoConnectionPoolTagsProvider customConnectionPoolTagsProvider() {
return new CustomConnectionPoolTagsProvider();
}
}
@Configuration(proxyBeanMethods = false)
class MyConnectionPoolTagsProviderConfiguration {
@Bean
fun customConnectionPoolTagsProvider(): MongoConnectionPoolTagsProvider {
return CustomConnectionPoolTagsProvider()
}
}
To disable the auto-configured connection pool metrics, set the following property:
management.metrics.mongo.connectionpool.enabled=false
management:
metrics:
mongo:
connectionpool:
enabled: false
Jetty Metrics
Auto-configuration binds metrics for Jetty’s ThreadPool
by using Micrometer’s JettyServerThreadPoolMetrics
.
Metrics for Jetty’s Connector
instances are bound by using Micrometer’s JettyConnectionMetrics
and, when server.ssl.enabled
is set to true
, Micrometer’s JettySslHandshakeMetrics
.
@Timed Annotation Support
To use @Timed
where it is not directly supported by Spring Boot, refer to the Micrometer documentation.
Redis Metrics
Auto-configuration registers a MicrometerCommandLatencyRecorder
for the auto-configured LettuceConnectionFactory
.
For more detail, see the Micrometer Metrics section of the Lettuce documentation.
13.7.4. Registering Custom Metrics
To register custom metrics, inject MeterRegistry
into your component:
@Component
public class MyBean {
private final Dictionary dictionary;
public MyBean(MeterRegistry registry) {
this.dictionary = Dictionary.load();
registry.gauge("dictionary.size", Tags.empty(), this.dictionary.getWords().size());
}
}
@Component
class MyBean(registry: MeterRegistry) {
private val dictionary: Dictionary
init {
dictionary = Dictionary.load()
registry.gauge("dictionary.size", Tags.empty(), dictionary.words.size)
}
}
If your metrics depend on other beans, we recommend that you use a MeterBinder
to register them:
public class MyMeterBinderConfiguration {
@Bean
public MeterBinder queueSize(Queue queue) {
return (registry) -> Gauge.builder("queueSize", queue::size).register(registry);
}
}
class MyMeterBinderConfiguration {
@Bean
fun queueSize(queue: Queue): MeterBinder {
return MeterBinder { registry ->
Gauge.builder("queueSize", queue::size).register(registry)
}
}
}
Using a MeterBinder
ensures that the correct dependency relationships are set up and that the bean is available when the metric’s value is retrieved.
A MeterBinder
implementation can also be useful if you find that you repeatedly instrument a suite of metrics across components or applications.
By default, metrics from all MeterBinder beans are automatically bound to the Spring-managed MeterRegistry .
|
13.7.5. Customizing Individual Metrics
If you need to apply customizations to specific Meter
instances, you can use the io.micrometer.core.instrument.config.MeterFilter
interface.
For example, if you want to rename the mytag.region
tag to mytag.area
for all meter IDs beginning with com.example
, you can do the following:
@Configuration(proxyBeanMethods = false)
public class MyMetricsFilterConfiguration {
@Bean
public MeterFilter renameRegionTagMeterFilter() {
return MeterFilter.renameTag("com.example", "mytag.region", "mytag.area");
}
}
@Configuration(proxyBeanMethods = false)
class MyMetricsFilterConfiguration {
@Bean
fun renameRegionTagMeterFilter(): MeterFilter {
return MeterFilter.renameTag("com.example", "mytag.region", "mytag.area")
}
}
By default, all MeterFilter beans are automatically bound to the Spring-managed MeterRegistry .
Make sure to register your metrics by using the Spring-managed MeterRegistry and not any of the static methods on Metrics .
These use the global registry that is not Spring-managed.
|
Common Tags
You can configure common tags using the management.observations.key-values
property.
The order of common tags is important if you use Graphite.
As the order of common tags cannot be guaranteed by using this approach, Graphite users are advised to define a custom MeterFilter instead.
|
Per-meter Properties
In addition to MeterFilter
beans, you can apply a limited set of customization on a per-meter basis using properties.
Per-meter customizations are applied, using Spring Boot’s PropertiesMeterFilter
, to any meter IDs that start with the given name.
The following example filters out any meters that have an ID starting with example.remote
.
management.metrics.enable.example.remote=false
management:
metrics:
enable:
example:
remote: false
The following properties allow per-meter customization:
Property | Description |
---|---|
|
Whether to accept meters with certain IDs.
Meters that are not accepted are filtered from the |
|
Whether to publish a histogram suitable for computing aggregable (across dimension) percentile approximations. |
|
Publish fewer histogram buckets by clamping the range of expected values. |
|
Publish percentile values computed in your application |
|
Give greater weight to recent samples by accumulating them in ring buffers which rotate after a configurable expiry, with a configurable buffer length. |
|
Publish a cumulative histogram with buckets defined by your service-level objectives. |
For more details on the concepts behind percentiles-histogram
, percentiles
, and slo
, see the “Histograms and percentiles” section of the Micrometer documentation.
13.7.6. Metrics Endpoint
Spring Boot provides a metrics
endpoint that you can use diagnostically to examine the metrics collected by an application.
The endpoint is not available by default and must be exposed.
See exposing endpoints for more details.
Navigating to /actuator/metrics
displays a list of available meter names.
You can drill down to view information about a particular meter by providing its name as a selector — for example, /actuator/metrics/jvm.memory.max
.
The name you use here should match the name used in the code, not the name after it has been naming-convention normalized for a monitoring system to which it is shipped.
In other words, if |
You can also add any number of tag=KEY:VALUE
query parameters to the end of the URL to dimensionally drill down on a meter — for example, /actuator/metrics/jvm.memory.max?tag=area:nonheap
.
The reported measurements are the sum of the statistics of all meters that match the meter name and any tags that have been applied.
In the preceding example, the returned |
13.8. Tracing
Spring Boot Actuator provides dependency management and auto-configuration for Micrometer Tracing, a facade for popular tracer libraries.
To learn more about Micrometer Tracing capabilities, see its reference documentation. |
13.8.1. Supported Tracers
Spring Boot ships auto-configuration for the following tracers:
-
OpenTelemetry with Zipkin, Wavefront, or OTLP
-
OpenZipkin Brave with Zipkin or Wavefront
13.8.2. Getting Started
We need an example application that we can use to get started with tracing. For our purposes, the simple “Hello World!” web application that’s covered in the “Developing Your First Spring Boot Application” section will suffice. We’re going to use the OpenTelemetry tracer with Zipkin as trace backend.
To recap, our main application code looks like this:
@RestController
@SpringBootApplication
public class MyApplication {
private static final Log logger = LogFactory.getLog(MyApplication.class);
@RequestMapping("/")
String home() {
logger.info("home() has been called");
return "Hello World!";
}
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
There’s an added logger statement in the home() method, which will be important later.
|
Now we have to add the following dependencies:
-
org.springframework.boot:spring-boot-starter-actuator
-
io.micrometer:micrometer-tracing-bridge-otel
- bridges the Micrometer Observation API to OpenTelemetry. -
io.opentelemetry:opentelemetry-exporter-zipkin
- reports traces to Zipkin.
Add the following application properties:
management.tracing.sampling.probability=1.0
management:
tracing:
sampling:
probability: 1.0
By default, Spring Boot samples only 10% of requests to prevent overwhelming the trace backend. This property switches it to 100% so that every request is sent to the trace backend.
To collect and visualize the traces, we need a running trace backend. We use Zipkin as our trace backend here. The Zipkin Quickstart guide provides instructions how to start Zipkin locally.
After Zipkin is running, you can start your application.
If you open a web browser to localhost:8080
, you should see the following output:
Hello World!
Behind the scenes, an observation has been created for the HTTP request, which in turn gets bridged to OpenTelemetry, which reports a new trace to Zipkin.
Now open the Zipkin UI at localhost:9411
and press the "Run Query" button to list all collected traces.
You should see one trace.
Press the "Show" button to see the details of that trace.
13.8.3. Logging Correlation IDs
Correlation IDs provide a helpful way to link lines in your log files to spans/traces.
By default, as long as management.tracing.enabled
has not been set to false
, Spring Boot will include correlation IDs in your logs whenever you are using Micrometer Tracing.
The default correlation ID is built from traceId
and spanId
MDC values.
For example, if Micrometer Tracing has added an MDC traceId
of 803B448A0489F84084905D3093480352
and an MDC spanId
of 3425F23BB2432450
the log output will include the correlation ID [803B448A0489F84084905D3093480352-3425F23BB2432450]
.
If you prefer to use a different format for your correlation ID, you can use the logging.pattern.correlation
property to define one.
For example, the following will provide a correlation ID for Logback in format previously used by Spring Cloud Sleuth:
logging.pattern.correlation=[${spring.application.name:},%X{traceId:-},%X{spanId:-}]
logging.include-application-name=false
logging:
pattern:
correlation: "[${spring.application.name:},%X{traceId:-},%X{spanId:-}] "
include-application-name: false
In the example above, logging.include-application-name is set to false to avoid the application name being duplicated in the log messages (logging.pattern.correlation already contains it).
It’s also worth mentioning that logging.pattern.correlation contains a trailing space so that it is separated from the logger name that comes right after it by default.
|
13.8.4. Propagating Traces
To automatically propagate traces over the network, use the auto-configured RestTemplateBuilder
or WebClient.Builder
to construct the client.
If you create the WebClient or the RestTemplate without using the auto-configured builders, automatic trace propagation won’t work!
|
13.8.5. Tracer Implementations
As Micrometer Tracer supports multiple tracer implementations, there are multiple dependency combinations possible with Spring Boot.
All tracer implementations need the org.springframework.boot:spring-boot-starter-actuator
dependency.
OpenTelemetry With Zipkin
Tracing with OpenTelemetry and reporting to Zipkin requires the following dependencies:
-
io.micrometer:micrometer-tracing-bridge-otel
- bridges the Micrometer Observation API to OpenTelemetry. -
io.opentelemetry:opentelemetry-exporter-zipkin
- reports traces to Zipkin.
Use the management.zipkin.tracing.*
configuration properties to configure reporting to Zipkin.
OpenTelemetry With Wavefront
Tracing with OpenTelemetry and reporting to Wavefront requires the following dependencies:
-
io.micrometer:micrometer-tracing-bridge-otel
- bridges the Micrometer Observation API to OpenTelemetry. -
io.micrometer:micrometer-tracing-reporter-wavefront
- reports traces to Wavefront.
Use the management.wavefront.*
configuration properties to configure reporting to Wavefront.
OpenTelemetry With OTLP
Tracing with OpenTelemetry and reporting using OTLP requires the following dependencies:
-
io.micrometer:micrometer-tracing-bridge-otel
- bridges the Micrometer Observation API to OpenTelemetry. -
io.opentelemetry:opentelemetry-exporter-otlp
- reports traces to a collector that can accept OTLP.
Use the management.otlp.tracing.*
configuration properties to configure reporting using OTLP.
OpenZipkin Brave With Zipkin
Tracing with OpenZipkin Brave and reporting to Zipkin requires the following dependencies:
-
io.micrometer:micrometer-tracing-bridge-brave
- bridges the Micrometer Observation API to Brave. -
io.zipkin.reporter2:zipkin-reporter-brave
- reports traces to Zipkin.
If your project doesn’t use Spring MVC or Spring WebFlux, the io.zipkin.reporter2:zipkin-sender-urlconnection dependency is needed, too.
|
Use the management.zipkin.tracing.*
configuration properties to configure reporting to Zipkin.
OpenZipkin Brave With Wavefront
Tracing with OpenZipkin Brave and reporting to Wavefront requires the following dependencies:
-
io.micrometer:micrometer-tracing-bridge-brave
- bridges the Micrometer Observation API to Brave. -
io.micrometer:micrometer-tracing-reporter-wavefront
- reports traces to Wavefront.
Use the management.wavefront.*
configuration properties to configure reporting to Wavefront.
13.8.6. Integration with Micrometer Observation
A TracingAwareMeterObservationHandler
is automatically registered on the ObservationRegistry
, which creates spans for every completed observation.
13.8.7. Creating Custom Spans
You can create your own spans by starting an observation.
For this, inject ObservationRegistry
into your component:
@Component
class CustomObservation {
private final ObservationRegistry observationRegistry;
CustomObservation(ObservationRegistry observationRegistry) {
this.observationRegistry = observationRegistry;
}
void someOperation() {
Observation observation = Observation.createNotStarted("some-operation", this.observationRegistry);
observation.lowCardinalityKeyValue("some-tag", "some-value");
observation.observe(() -> {
// Business logic ...
});
}
}
This will create an observation named "some-operation" with the tag "some-tag=some-value".
If you want to create a span without creating a metric, you need to use the lower-level Tracer API from Micrometer.
|
13.8.8. Baggage
You can create baggage with the Tracer
API:
@Component
class CreatingBaggage {
private final Tracer tracer;
CreatingBaggage(Tracer tracer) {
this.tracer = tracer;
}
void doSomething() {
try (BaggageInScope scope = this.tracer.createBaggageInScope("baggage1", "value1")) {
// Business logic
}
}
}
This example creates baggage named baggage1
with the value value1
.
The baggage is automatically propagated over the network if you’re using W3C propagation.
If you’re using B3 propagation, baggage is not automatically propagated.
To manually propagate baggage over the network, use the management.tracing.baggage.remote-fields
configuration property (this works for W3C, too).
For the example above, setting this property to baggage1
results in an HTTP header baggage1: value1
.
If you want to propagate the baggage to the MDC, use the management.tracing.baggage.correlation.fields
configuration property.
For the example above, setting this property to baggage1
results in an MDC entry named baggage1
.
13.8.9. Tests
Tracing components which are reporting data are not auto-configured when using @SpringBootTest
.
See the testing section for more details.
13.9. Auditing
Once Spring Security is in play, Spring Boot Actuator has a flexible audit framework that publishes events (by default, “authentication success”, “failure” and “access denied” exceptions). This feature can be very useful for reporting and for implementing a lock-out policy based on authentication failures.
You can enable auditing by providing a bean of type AuditEventRepository
in your application’s configuration.
For convenience, Spring Boot offers an InMemoryAuditEventRepository
.
InMemoryAuditEventRepository
has limited capabilities, and we recommend using it only for development environments.
For production environments, consider creating your own alternative AuditEventRepository
implementation.
13.9.1. Custom Auditing
To customize published security events, you can provide your own implementations of AbstractAuthenticationAuditListener
and AbstractAuthorizationAuditListener
.
You can also use the audit services for your own business events.
To do so, either inject the AuditEventRepository
bean into your own components and use that directly or publish an AuditApplicationEvent
with the Spring ApplicationEventPublisher
(by implementing ApplicationEventPublisherAware
).
13.10. Recording HTTP Exchanges
You can enable recording of HTTP exchanges by providing a bean of type HttpExchangeRepository
in your application’s configuration.
For convenience, Spring Boot offers InMemoryHttpExchangeRepository
, which, by default, stores the last 100 request-response exchanges.
InMemoryHttpExchangeRepository
is limited compared to tracing solutions, and we recommend using it only for development environments.
For production environments, we recommend using a production-ready tracing or observability solution, such as Zipkin or OpenTelemetry.
Alternatively, you can create your own HttpExchangeRepository
.
You can use the httpexchanges
endpoint to obtain information about the request-response exchanges that are stored in the HttpExchangeRepository
.
13.11. Process Monitoring
In the spring-boot
module, you can find two classes to create files that are often useful for process monitoring:
-
ApplicationPidFileWriter
creates a file that contains the application PID (by default, in the application directory with a file name ofapplication.pid
). -
WebServerPortFileWriter
creates a file (or files) that contain the ports of the running web server (by default, in the application directory with a file name ofapplication.port
).
By default, these writers are not activated, but you can enable them:
13.11.1. Extending Configuration
In the META-INF/spring.factories
file, you can activate the listener (or listeners) that writes a PID file:
org.springframework.context.ApplicationListener=\ org.springframework.boot.context.ApplicationPidFileWriter,\ org.springframework.boot.web.context.WebServerPortFileWriter
13.12. Cloud Foundry Support
Spring Boot’s actuator module includes additional support that is activated when you deploy to a compatible Cloud Foundry instance.
The /cloudfoundryapplication
path provides an alternative secured route to all @Endpoint
beans.
The extended support lets Cloud Foundry management UIs (such as the web application that you can use to view deployed applications) be augmented with Spring Boot actuator information. For example, an application status page can include full health information instead of the typical “running” or “stopped” status.
The /cloudfoundryapplication path is not directly accessible to regular users.
To use the endpoint, you must pass a valid UAA token with the request.
|
13.12.1. Disabling Extended Cloud Foundry Actuator Support
If you want to fully disable the /cloudfoundryapplication
endpoints, you can add the following setting to your application.properties
file:
management.cloudfoundry.enabled=false
management:
cloudfoundry:
enabled: false
13.12.2. Cloud Foundry Self-signed Certificates
By default, the security verification for /cloudfoundryapplication
endpoints makes SSL calls to various Cloud Foundry services.
If your Cloud Foundry UAA or Cloud Controller services use self-signed certificates, you need to set the following property:
management.cloudfoundry.skip-ssl-validation=true
management:
cloudfoundry:
skip-ssl-validation: true
13.12.3. Custom Context Path
If the server’s context-path has been configured to anything other than /
, the Cloud Foundry endpoints are not available at the root of the application.
For example, if server.servlet.context-path=/app
, Cloud Foundry endpoints are available at /app/cloudfoundryapplication/*
.
If you expect the Cloud Foundry endpoints to always be available at /cloudfoundryapplication/*
, regardless of the server’s context-path, you need to explicitly configure that in your application.
The configuration differs, depending on the web server in use.
For Tomcat, you can add the following configuration:
@Configuration(proxyBeanMethods = false)
public class MyCloudFoundryConfiguration {
@Bean
public TomcatServletWebServerFactory servletWebServerFactory() {
return new TomcatServletWebServerFactory() {
@Override
protected void prepareContext(Host host, ServletContextInitializer[] initializers) {
super.prepareContext(host, initializers);
StandardContext child = new StandardContext();
child.addLifecycleListener(new Tomcat.FixContextListener());
child.setPath("/cloudfoundryapplication");
ServletContainerInitializer initializer = getServletContextInitializer(getContextPath());
child.addServletContainerInitializer(initializer, Collections.emptySet());
child.setCrossContext(true);
host.addChild(child);
}
};
}
private ServletContainerInitializer getServletContextInitializer(String contextPath) {
return (classes, context) -> {
Servlet servlet = new GenericServlet() {
@Override
public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
ServletContext context = req.getServletContext().getContext(contextPath);
context.getRequestDispatcher("/cloudfoundryapplication").forward(req, res);
}
};
context.addServlet("cloudfoundry", servlet).addMapping("/*");
};
}
}
@Configuration(proxyBeanMethods = false)
class MyCloudFoundryConfiguration {
@Bean
fun servletWebServerFactory(): TomcatServletWebServerFactory {
return object : TomcatServletWebServerFactory() {
override fun prepareContext(host: Host, initializers: Array<ServletContextInitializer>) {
super.prepareContext(host, initializers)
val child = StandardContext()
child.addLifecycleListener(FixContextListener())
child.path = "/cloudfoundryapplication"
val initializer = getServletContextInitializer(contextPath)
child.addServletContainerInitializer(initializer, emptySet())
child.crossContext = true
host.addChild(child)
}
}
}
private fun getServletContextInitializer(contextPath: String): ServletContainerInitializer {
return ServletContainerInitializer { classes: Set<Class<*>?>?, context: ServletContext ->
val servlet: Servlet = object : GenericServlet() {
@Throws(ServletException::class, IOException::class)
override fun service(req: ServletRequest, res: ServletResponse) {
val servletContext = req.servletContext.getContext(contextPath)
servletContext.getRequestDispatcher("/cloudfoundryapplication").forward(req, res)
}
}
context.addServlet("cloudfoundry", servlet).addMapping("/*")
}
}
}
If you’re using a Webflux based application, you can use the following configuration:
@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties(WebFluxProperties.class)
public class MyReactiveCloudFoundryConfiguration {
@Bean
public HttpHandler httpHandler(ApplicationContext applicationContext, WebFluxProperties properties) {
HttpHandler httpHandler = WebHttpHandlerBuilder.applicationContext(applicationContext).build();
return new CloudFoundryHttpHandler(properties.getBasePath(), httpHandler);
}
private static final class CloudFoundryHttpHandler implements HttpHandler {
private final HttpHandler delegate;
private final ContextPathCompositeHandler contextPathDelegate;
private CloudFoundryHttpHandler(String basePath, HttpHandler delegate) {
this.delegate = delegate;
this.contextPathDelegate = new ContextPathCompositeHandler(Map.of(basePath, delegate));
}
@Override
public Mono<Void> handle(ServerHttpRequest request, ServerHttpResponse response) {
// Remove underlying context path first (e.g. Servlet container)
String path = request.getPath().pathWithinApplication().value();
if (path.startsWith("/cloudfoundryapplication")) {
return this.delegate.handle(request, response);
}
else {
return this.contextPathDelegate.handle(request, response);
}
}
}
}
@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties(WebFluxProperties::class)
class MyReactiveCloudFoundryConfiguration {
@Bean
fun httpHandler(applicationContext: ApplicationContext, properties: WebFluxProperties): HttpHandler {
val httpHandler = WebHttpHandlerBuilder.applicationContext(applicationContext).build()
return CloudFoundryHttpHandler(properties.basePath, httpHandler)
}
private class CloudFoundryHttpHandler(basePath: String, private val delegate: HttpHandler) : HttpHandler {
private val contextPathDelegate = ContextPathCompositeHandler(mapOf(basePath to delegate))
override fun handle(request: ServerHttpRequest, response: ServerHttpResponse): Mono<Void> {
// Remove underlying context path first (e.g. Servlet container)
val path = request.path.pathWithinApplication().value()
return if (path.startsWith("/cloudfoundryapplication")) {
delegate.handle(request, response)
} else {
contextPathDelegate.handle(request, response)
}
}
}
}
13.13. What to Read Next
You might want to read about graphing tools such as Graphite.
Otherwise, you can continue on to read about “deployment options” or jump ahead for some in-depth information about Spring Boot’s build tool plugins.
14. Deploying Spring Boot Applications
Spring Boot’s flexible packaging options provide a great deal of choice when it comes to deploying your application. You can deploy Spring Boot applications to a variety of cloud platforms, to virtual/real machines, or make them fully executable for Unix systems.
This section covers some of the more common deployment scenarios.
14.1. Deploying to the Cloud
Spring Boot’s executable jars are ready-made for most popular cloud PaaS (Platform-as-a-Service) providers. These providers tend to require that you “bring your own container”. They manage application processes (not Java applications specifically), so they need an intermediary layer that adapts your application to the cloud’s notion of a running process.
Two popular cloud providers, Heroku and Cloud Foundry, employ a “buildpack” approach.
The buildpack wraps your deployed code in whatever is needed to start your application.
It might be a JDK and a call to java
, an embedded web server, or a full-fledged application server.
A buildpack is pluggable, but ideally you should be able to get by with as few customizations to it as possible.
This reduces the footprint of functionality that is not under your control.
It minimizes divergence between development and production environments.
Ideally, your application, like a Spring Boot executable jar, has everything that it needs to run packaged within it.
In this section, we look at what it takes to get the application that we developed in the “Getting Started” section up and running in the Cloud.
14.1.1. Cloud Foundry
Cloud Foundry provides default buildpacks that come into play if no other buildpack is specified.
The Cloud Foundry Java buildpack has excellent support for Spring applications, including Spring Boot.
You can deploy stand-alone executable jar applications as well as traditional .war
packaged applications.
Once you have built your application (by using, for example, mvn clean package
) and have installed the cf
command line tool, deploy your application by using the cf push
command, substituting the path to your compiled .jar
.
Be sure to have logged in with your cf
command line client before pushing an application.
The following line shows using the cf push
command to deploy an application:
$ cf push acloudyspringtime -p target/demo-0.0.1-SNAPSHOT.jar
In the preceding example, we substitute acloudyspringtime for whatever value you give cf as the name of your application.
|
See the cf push
documentation for more options.
If there is a Cloud Foundry manifest.yml
file present in the same directory, it is considered.
At this point, cf
starts uploading your application, producing output similar to the following example:
Uploading acloudyspringtime... OK Preparing to start acloudyspringtime... OK -----> Downloaded app package (8.9M) -----> Java Buildpack Version: v3.12 (offline) | https://github.com/cloudfoundry/java-buildpack.git#6f25b7e -----> Downloading Open Jdk JRE Expanding Open Jdk JRE to .java-buildpack/open_jdk_jre (1.6s) -----> Downloading Open JDK Like Memory Calculator 2.0.2_RELEASE from https://java-buildpack.cloudfoundry.org/memory-calculator/trusty/x86_64/memory-calculator-2.0.2_RELEASE.tar.gz (found in cache) Memory Settings: -Xss349K -Xmx681574K -XX:MaxMetaspaceSize=104857K -Xms681574K -XX:MetaspaceSize=104857K -----> Downloading Container Certificate Trust Store 1.0.0_RELEASE from https://java-buildpack.cloudfoundry.org/container-certificate-trust-store/container-certificate-trust-store-1.0.0_RELEASE.jar (found in cache) Adding certificates to .java-buildpack/container_certificate_trust_store/truststore.jks (0.6s) -----> Downloading Spring Auto Reconfiguration 1.10.0_RELEASE from https://java-buildpack.cloudfoundry.org/auto-reconfiguration/auto-reconfiguration-1.10.0_RELEASE.jar (found in cache) Checking status of app 'acloudyspringtime'... 0 of 1 instances running (1 starting) ... 0 of 1 instances running (1 starting) ... 0 of 1 instances running (1 starting) ... 1 of 1 instances running (1 running) App started
Congratulations! The application is now live!
Once your application is live, you can verify the status of the deployed application by using the cf apps
command, as shown in the following example:
$ cf apps
Getting applications in ...
OK
name requested state instances memory disk urls
...
acloudyspringtime started 1/1 512M 1G acloudyspringtime.cfapps.io
...
Once Cloud Foundry acknowledges that your application has been deployed, you should be able to find the application at the URI given.
In the preceding example, you could find it at https://acloudyspringtime.cfapps.io/
.
Binding to Services
By default, metadata about the running application as well as service connection information is exposed to the application as environment variables (for example: $VCAP_SERVICES
).
This architecture decision is due to Cloud Foundry’s polyglot (any language and platform can be supported as a buildpack) nature.
Process-scoped environment variables are language agnostic.
Environment variables do not always make for the easiest API, so Spring Boot automatically extracts them and flattens the data into properties that can be accessed through Spring’s Environment
abstraction, as shown in the following example:
@Component
public class MyBean implements EnvironmentAware {
private String instanceId;
@Override
public void setEnvironment(Environment environment) {
this.instanceId = environment.getProperty("vcap.application.instance_id");
}
// ...
}
@Component
class MyBean : EnvironmentAware {
private var instanceId: String? = null
override fun setEnvironment(environment: Environment) {
instanceId = environment.getProperty("vcap.application.instance_id")
}
// ...
}
All Cloud Foundry properties are prefixed with vcap
.
You can use vcap
properties to access application information (such as the public URL of the application) and service information (such as database credentials).
See the CloudFoundryVcapEnvironmentPostProcessor
Javadoc for complete details.
The Java CFEnv project is a better fit for tasks such as configuring a DataSource. |
14.1.2. Kubernetes
Spring Boot auto-detects Kubernetes deployment environments by checking the environment for "*_SERVICE_HOST"
and "*_SERVICE_PORT"
variables.
You can override this detection with the spring.main.cloud-platform
configuration property.
Spring Boot helps you to manage the state of your application and export it with HTTP Kubernetes Probes using Actuator.
Kubernetes Container Lifecycle
When Kubernetes deletes an application instance, the shutdown process involves several subsystems concurrently: shutdown hooks, unregistering the service, removing the instance from the load-balancer… Because this shutdown processing happens in parallel (and due to the nature of distributed systems), there is a window during which traffic can be routed to a pod that has also begun its shutdown processing.
You can configure a sleep execution in a preStop handler to avoid requests being routed to a pod that has already begun shutting down. This sleep should be long enough for new requests to stop being routed to the pod and its duration will vary from deployment to deployment. The preStop handler can be configured by using the PodSpec in the pod’s configuration file as follows:
spec:
containers:
- name: "example-container"
image: "example-image"
lifecycle:
preStop:
exec:
command: ["sh", "-c", "sleep 10"]
Once the pre-stop hook has completed, SIGTERM will be sent to the container and graceful shutdown will begin, allowing any remaining in-flight requests to complete.
When Kubernetes sends a SIGTERM signal to the pod, it waits for a specified time called the termination grace period (the default for which is 30 seconds).
If the containers are still running after the grace period, they are sent the SIGKILL signal and forcibly removed.
If the pod takes longer than 30 seconds to shut down, which could be because you have increased spring.lifecycle.timeout-per-shutdown-phase , make sure to increase the termination grace period by setting the terminationGracePeriodSeconds option in the Pod YAML.
|
14.1.3. Heroku
Heroku is another popular PaaS platform.
To customize Heroku builds, you provide a Procfile
, which provides the incantation required to deploy an application.
Heroku assigns a port
for the Java application to use and then ensures that routing to the external URI works.
You must configure your application to listen on the correct port.
The following example shows the Procfile
for our starter REST application:
web: java -Dserver.port=$PORT -jar target/demo-0.0.1-SNAPSHOT.jar
Spring Boot makes -D
arguments available as properties accessible from a Spring Environment
instance.
The server.port
configuration property is fed to the embedded Tomcat, Jetty, or Undertow instance, which then uses the port when it starts up.
The $PORT
environment variable is assigned to us by the Heroku PaaS.
This should be everything you need.
The most common deployment workflow for Heroku deployments is to git push
the code to production, as shown in the following example:
$ git push heroku main
Which will result in the following:
Initializing repository, done. Counting objects: 95, done. Delta compression using up to 8 threads. Compressing objects: 100% (78/78), done. Writing objects: 100% (95/95), 8.66 MiB | 606.00 KiB/s, done. Total 95 (delta 31), reused 0 (delta 0) -----> Java app detected -----> Installing OpenJDK... done -----> Installing Maven... done -----> Installing settings.xml... done -----> Executing: mvn -B -DskipTests=true clean install [INFO] Scanning for projects... Downloading: https://repo.spring.io/... Downloaded: https://repo.spring.io/... (818 B at 1.8 KB/sec) .... Downloaded: https://s3pository.heroku.com/jvm/... (152 KB at 595.3 KB/sec) [INFO] Installing /tmp/build_0c35a5d2-a067-4abc-a232-14b1fb7a8229/target/... [INFO] Installing /tmp/build_0c35a5d2-a067-4abc-a232-14b1fb7a8229/pom.xml ... [INFO] ------------------------------------------------------------------------ [INFO] BUILD SUCCESS [INFO] ------------------------------------------------------------------------ [INFO] Total time: 59.358s [INFO] Finished at: Fri Mar 07 07:28:25 UTC 2014 [INFO] Final Memory: 20M/493M [INFO] ------------------------------------------------------------------------ -----> Discovering process types Procfile declares types -> web -----> Compressing... done, 70.4MB -----> Launching... done, v6 https://agile-sierra-1405.herokuapp.com/ deployed to Heroku To [email protected]:agile-sierra-1405.git * [new branch] main -> main
Your application should now be up and running on Heroku. For more details, see Deploying Spring Boot Applications to Heroku.
14.1.4. OpenShift
OpenShift has many resources describing how to deploy Spring Boot applications, including:
14.1.5. Amazon Web Services (AWS)
Amazon Web Services offers multiple ways to install Spring Boot-based applications, either as traditional web applications (war) or as executable jar files with an embedded web server. The options include:
-
AWS Elastic Beanstalk
-
AWS Code Deploy
-
AWS OPS Works
-
AWS Cloud Formation
-
AWS Container Registry
Each has different features and pricing models. In this document, we describe to approach using AWS Elastic Beanstalk.
AWS Elastic Beanstalk
As described in the official Elastic Beanstalk Java guide, there are two main options to deploy a Java application. You can either use the “Tomcat Platform” or the “Java SE platform”.
Using the Tomcat Platform
This option applies to Spring Boot projects that produce a war file. No special configuration is required. You need only follow the official guide.
Using the Java SE Platform
This option applies to Spring Boot projects that produce a jar file and run an embedded web container.
Elastic Beanstalk environments run an nginx instance on port 80 to proxy the actual application, running on port 5000.
To configure it, add the following line to your application.properties
file:
server.port=5000
Upload binaries instead of sources
By default, Elastic Beanstalk uploads sources and compiles them in AWS.
However, it is best to upload the binaries instead.
To do so, add lines similar to the following to your
|
Reduce costs by setting the environment type
By default an Elastic Beanstalk environment is load balanced. The load balancer has a significant cost. To avoid that cost, set the environment type to “Single instance”, as described in the Amazon documentation. You can also create single instance environments by using the CLI and the following command: eb create -s |
Summary
This is one of the easiest ways to get to AWS, but there are more things to cover, such as how to integrate Elastic Beanstalk into any CI / CD tool, use the Elastic Beanstalk Maven plugin instead of the CLI, and others. There is a blog post covering these topics more in detail.
14.1.6. CloudCaptain and Amazon Web Services
CloudCaptain works by turning your Spring Boot executable jar or war into a minimal VM image that can be deployed unchanged either on VirtualBox or on AWS. CloudCaptain comes with deep integration for Spring Boot and uses the information from your Spring Boot configuration file to automatically configure ports and health check URLs. CloudCaptain leverages this information both for the images it produces as well as for all the resources it provisions (instances, security groups, elastic load balancers, and so on).
Once you have created a CloudCaptain account, connected it to your AWS account, installed the latest version of the CloudCaptain Client, and ensured that the application has been built by Maven or Gradle (by using, for example, mvn clean package
), you can deploy your Spring Boot application to AWS with a command similar to the following:
$ boxfuse run myapp-1.0.jar -env=prod
See the boxfuse run
documentation for more options.
If there is a boxfuse.conf
file present in the current directory, it is considered.
By default, CloudCaptain activates a Spring profile named boxfuse on startup.
If your executable jar or war contains an application-boxfuse.properties file, CloudCaptain bases its configuration on the properties it contains.
|
At this point, CloudCaptain creates an image for your application, uploads it, and configures and starts the necessary resources on AWS, resulting in output similar to the following example:
Fusing Image for myapp-1.0.jar ... Image fused in 00:06.838s (53937 K) -> axelfontaine/myapp:1.0 Creating axelfontaine/myapp ... Pushing axelfontaine/myapp:1.0 ... Verifying axelfontaine/myapp:1.0 ... Creating Elastic IP ... Mapping myapp-axelfontaine.boxfuse.io to 52.28.233.167 ... Waiting for AWS to create an AMI for axelfontaine/myapp:1.0 in eu-central-1 (this may take up to 50 seconds) ... AMI created in 00:23.557s -> ami-d23f38cf Creating security group boxfuse-sg_axelfontaine/myapp:1.0 ... Launching t2.micro instance of axelfontaine/myapp:1.0 (ami-d23f38cf) in eu-central-1 ... Instance launched in 00:30.306s -> i-92ef9f53 Waiting for AWS to boot Instance i-92ef9f53 and Payload to start at https://52.28.235.61/ ... Payload started in 00:29.266s -> https://52.28.235.61/ Remapping Elastic IP 52.28.233.167 to i-92ef9f53 ... Waiting 15s for AWS to complete Elastic IP Zero Downtime transition ... Deployment completed successfully. axelfontaine/myapp:1.0 is up and running at https://myapp-axelfontaine.boxfuse.io/
Your application should now be up and running on AWS.
See the blog post on deploying Spring Boot apps on EC2 as well as the documentation for the CloudCaptain Spring Boot integration to get started with a Maven build to run the app.
14.1.7. Azure
This Getting Started guide walks you through deploying your Spring Boot application to either Azure Spring Cloud or Azure App Service.
14.1.8. Google Cloud
Google Cloud has several options that can be used to launch Spring Boot applications. The easiest to get started with is probably App Engine, but you could also find ways to run Spring Boot in a container with Container Engine or on a virtual machine with Compute Engine.
To deploy your first app to App Engine standard environment, follow this tutorial.
Alternatively, App Engine Flex requires you to create an app.yaml
file to describe the resources your app requires.
Normally, you put this file in src/main/appengine
, and it should resemble the following file:
service: "default"
runtime: "java17"
env: "flex"
handlers:
- url: "/.*"
script: "this field is required, but ignored"
manual_scaling:
instances: 1
health_check:
enable_health_check: false
env_variables:
ENCRYPT_KEY: "your_encryption_key_here"
You can deploy the app (for example, with a Maven plugin) by adding the project ID to the build configuration, as shown in the following example:
<plugin>
<groupId>com.google.cloud.tools</groupId>
<artifactId>appengine-maven-plugin</artifactId>
<version>2.4.4</version>
<configuration>
<project>myproject</project>
</configuration>
</plugin>
Then deploy with mvn appengine:deploy
(you need to authenticate first, otherwise the build fails).
14.2. Installing Spring Boot Applications
In addition to running Spring Boot applications by using java -jar
directly, it is also possible to run them as systemd
, init.d
or Windows services.
14.2.1. Installation as a systemd Service
systemd
is the successor of the System V init system and is now being used by many modern Linux distributions.
Spring Boot applications can be launched by using systemd
‘service’ scripts.
Assuming that you have a Spring Boot application packaged as an uber jar in /var/myapp
, to install it as a systemd
service, create a script named myapp.service
and place it in /etc/systemd/system
directory.
The following script offers an example:
[Unit] Description=myapp After=syslog.target network.target [Service] User=myapp Group=myapp Environment="JAVA_HOME=/path/to/java/home" ExecStart=${JAVA_HOME}/bin/java -jar /var/myapp/myapp.jar ExecStop=/bin/kill -15 $MAINPID SuccessExitStatus=143 [Install] WantedBy=multi-user.target
Remember to change the Description , User , Group , Environment and ExecStart fields for your application.
|
The ExecStart field does not declare the script action command, which means that the run command is used by default.
|
The user that runs the application, the PID file, and the console log file are managed by systemd
itself and therefore must be configured by using appropriate fields in the ‘service’ script.
Consult the service unit configuration man page for more details.
To flag the application to start automatically on system boot, use the following command:
$ systemctl enable myapp.service
Run man systemctl
for more details.
14.2.2. Installation as an init.d Service (System V)
To use your application as init.d
service, configure its build to produce a fully executable jar.
Fully executable jars work by embedding an extra script at the front of the file.
Currently, some tools do not accept this format, so you may not always be able to use this technique.
For example, jar -xf may silently fail to extract a jar or war that has been made fully executable.
It is recommended that you make your jar or war fully executable only if you intend to execute it directly, rather than running it with java -jar or deploying it to a servlet container.
|
A zip64-format jar file cannot be made fully executable.
Attempting to do so will result in a jar file that is reported as corrupt when executed directly or with java -jar .
A standard-format jar file that contains one or more zip64-format nested jars can be fully executable.
|
To create a ‘fully executable’ jar with Maven, use the following plugin configuration:
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<executable>true</executable>
</configuration>
</plugin>
The following example shows the equivalent Gradle configuration:
tasks.named('bootJar') {
launchScript()
}
It can then be symlinked to init.d
to support the standard start
, stop
, restart
, and status
commands.
The default launch script that is added to a fully executable jar supports most Linux distributions and is tested on CentOS and Ubuntu. Other platforms, such as OS X and FreeBSD, require the use of a custom script. The default scripts supports the following features:
-
Starts the services as the user that owns the jar file
-
Tracks the application’s PID by using
/var/run/<appname>/<appname>.pid
-
Writes console logs to
/var/log/<appname>.log
Assuming that you have a Spring Boot application installed in /var/myapp
, to install a Spring Boot application as an init.d
service, create a symlink, as follows:
$ sudo ln -s /var/myapp/myapp.jar /etc/init.d/myapp
Once installed, you can start and stop the service in the usual way. For example, on a Debian-based system, you could start it with the following command:
$ service myapp start
If your application fails to start, check the log file written to /var/log/<appname>.log for errors.
|
You can also flag the application to start automatically by using your standard operating system tools. For example, on Debian, you could use the following command:
$ update-rc.d myapp defaults <priority>
Securing an init.d Service
The following is a set of guidelines on how to secure a Spring Boot application that runs as an init.d service. It is not intended to be an exhaustive list of everything that should be done to harden an application and the environment in which it runs. |
When executed as root, as is the case when root is being used to start an init.d service, the default executable script runs the application as the user specified in the RUN_AS_USER
environment variable.
When the environment variable is not set, the user who owns the jar file is used instead.
You should never run a Spring Boot application as root
, so RUN_AS_USER
should never be root and your application’s jar file should never be owned by root.
Instead, create a specific user to run your application and set the RUN_AS_USER
environment variable or use chown
to make it the owner of the jar file, as shown in the following example:
$ chown bootapp:bootapp your-app.jar
In this case, the default executable script runs the application as the bootapp
user.
To reduce the chances of the application’s user account being compromised, you should consider preventing it from using a login shell.
For example, you can set the account’s shell to /usr/sbin/nologin .
|
You should also take steps to prevent the modification of your application’s jar file. Firstly, configure its permissions so that it cannot be written and can only be read or executed by its owner, as shown in the following example:
$ chmod 500 your-app.jar
Second, you should also take steps to limit the damage if your application or the account that is running it is compromised.
If an attacker does gain access, they could make the jar file writable and change its contents.
One way to protect against this is to make it immutable by using chattr
, as shown in the following example:
$ sudo chattr +i your-app.jar
This will prevent any user, including root, from modifying the jar.
If root is used to control the application’s service and you use a .conf
file to customize its startup, the .conf
file is read and evaluated by the root user.
It should be secured accordingly.
Use chmod
so that the file can only be read by the owner and use chown
to make root the owner, as shown in the following example:
$ chmod 400 your-app.conf
$ sudo chown root:root your-app.conf
Customizing the Startup Script
The default embedded startup script written by the Maven or Gradle plugin can be customized in a number of ways.
For most people, using the default script along with a few customizations is usually enough.
If you find you cannot customize something that you need to, use the embeddedLaunchScript
option to write your own file entirely.
Customizing the Start Script When It Is Written
It often makes sense to customize elements of the start script as it is written into the jar file. For example, init.d scripts can provide a “description”. Since you know the description up front (and it need not change), you may as well provide it when the jar is generated.
To customize written elements, use the embeddedLaunchScriptProperties
option of the Spring Boot Maven plugin or the properties
property of the Spring Boot Gradle plugin’s launchScript
.
The following property substitutions are supported with the default script:
Name | Description | Gradle default | Maven default |
---|---|---|---|
|
The script mode. |
|
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|
The |
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Single-line version of |
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|
|
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The default value for |
Folder containing the jar |
Folder containing the jar |
|
Reference to a file script that should be inlined in the default launch script.
This can be used to set environmental variables such as |
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Default value for |
||
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Default value for |
||
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Default value for |
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Default value for the name of the PID file in |
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Whether the |
|
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Default value for |
60 |
60 |
Customizing a Script When It Runs
For items of the script that need to be customized after the jar has been written, you can use environment variables or a config file.
The following environment properties are supported with the default script:
Variable | Description |
---|---|
|
The “mode” of operation.
The default depends on the way the jar was built but is usually |
|
The user that will be used to run the application. When not set, the user that owns the jar file will be used. |
|
Whether the |
|
The root name of the pid folder ( |
|
The name of the folder in which to put log files ( |
|
The name of the folder from which to read .conf files (same folder as jar-file by default). |
|
The name of the log file in the |
|
The name of the app. If the jar is run from a symlink, the script guesses the app name. If it is not a symlink or you want to explicitly set the app name, this can be useful. |
|
The arguments to pass to the program (the Spring Boot app). |
|
The location of the |
|
Options that are passed to the JVM when it is launched. |
|
The explicit location of the jar file, in case the script is being used to launch a jar that it is not actually embedded. |
|
If not empty, sets the |
|
The time in seconds to wait when stopping the application before forcing a shutdown ( |
The PID_FOLDER , LOG_FOLDER , and LOG_FILENAME variables are only valid for an init.d service.
For systemd , the equivalent customizations are made by using the ‘service’ script.
See the service unit configuration man page for more details.
|
With the exception of JARFILE
and APP_NAME
, the settings listed in the preceding section can be configured by using a .conf
file.
The file is expected to be next to the jar file and have the same name but suffixed with .conf
rather than .jar
.
For example, a jar named /var/myapp/myapp.jar
uses the configuration file named /var/myapp/myapp.conf
, as shown in the following example:
JAVA_OPTS=-Xmx1024M LOG_FOLDER=/custom/log/folder
If you do not like having the config file next to the jar file, you can set a CONF_FOLDER environment variable to customize the location of the config file.
|
To learn about securing this file appropriately, see the guidelines for securing an init.d service.
14.2.3. Microsoft Windows Services
A Spring Boot application can be started as a Windows service by using winsw
.
A (separately maintained sample) describes step-by-step how you can create a Windows service for your Spring Boot application.
14.3. Efficient deployments
14.3.1. Unpacking the Executable JAR
If you are running your application from a container, you can use an executable jar, but it is also often an advantage to explode it and run it in a different way. Certain PaaS implementations may also choose to unpack archives before they run. For example, Cloud Foundry operates this way. One way to run an unpacked archive is by starting the appropriate launcher, as follows:
$ jar -xf myapp.jar
$ java org.springframework.boot.loader.launch.JarLauncher
This is actually slightly faster on startup (depending on the size of the jar) than running from an unexploded archive. After startup, you should not expect any differences.
Once you have unpacked the jar file, you can also get an extra boost to startup time by running the app with its "natural" main method instead of the JarLauncher
. For example:
$ jar -xf myapp.jar
$ java -cp "BOOT-INF/classes:BOOT-INF/lib/*" com.example.MyApplication
Using the JarLauncher over the application’s main method has the added benefit of a predictable classpath order.
The jar contains a classpath.idx file which is used by the JarLauncher when constructing the classpath.
|
14.3.2. Using Ahead-of-time Processing With the JVM
It’s beneficial for the startup time to run your application using the AOT generated initialization code. First, you need to ensure that the jar you are building includes AOT generated code.
For Maven, this means that you should build with -Pnative
to activate the native
profile:
$ mvn -Pnative package
For Gradle, you need to ensure that your build includes the org.springframework.boot.aot
plugin.
When the JAR has been built, run it with spring.aot.enabled
system property set to true
. For example:
$ java -Dspring.aot.enabled=true -jar myapplication.jar
........ Starting AOT-processed MyApplication ...
Beware that using the ahead-of-time processing has drawbacks. It implies the following restrictions:
-
The classpath is fixed and fully defined at build time
-
The beans defined in your application cannot change at runtime, meaning:
-
The Spring
@Profile
annotation and profile-specific configuration have limitations. -
Properties that change if a bean is created are not supported (for example,
@ConditionalOnProperty
and.enable
properties).
-
To learn more about ahead-of-time processing, please see the Understanding Spring Ahead-of-Time Processing section.
14.3.3. Checkpoint and Restore With the JVM
Coordinated Restore at Checkpoint (CRaC) is an OpenJDK project that defines a new Java API to allow you to checkpoint and restore an application on the HotSpot JVM. It is based on CRIU, a project that implements checkpoint/restore functionality on Linux.
The principle is the following: you start your application almost as usual but with a CRaC enabled version of the JDK like Bellsoft Liberica JDK with CRaC or Azul Zulu JDK with CRaC.
Then at some point, potentially after some workloads that will warm up your JVM by executing all common code paths, you trigger a checkpoint using an API call, a jcmd
command, an HTTP endpoint, or a different mechanism.
A memory representation of the running JVM, including its warmness, is then serialized to disk, allowing a fast restoration at a later point, potentially on another machine with a similar operating system and CPU architecture. The restored process retains all the capabilities of the HotSpot JVM, including further JIT optimizations at runtime.
Based on the foundations provided by Spring Framework, Spring Boot provides support for checkpointing and restoring your application, and manages out-of-the-box the lifecycle of resources such as socket, files and thread pools on a limited scope. Additional lifecycle management is expected for other dependencies and potentially for the application code dealing with such resources.
You can find more details about the two modes supported ("on demand checkpoint/restore of a running application" and "automatic checkpoint/restore at startup"), how to enable checkpoint and restore support and some guidelines in the Spring Framework JVM Checkpoint Restore support documentation.
14.4. What to Read Next
See the Cloud Foundry, Heroku, OpenShift, and Boxfuse web sites for more information about the kinds of features that a PaaS can offer. These are just four of the most popular Java PaaS providers. Since Spring Boot is so amenable to cloud-based deployment, you can freely consider other providers as well.
The next section goes on to cover the GraalVM Native Images, or you can jump ahead to read about the Spring Boot CLI or our build tool plugins.
15. GraalVM Native Image Support
GraalVM Native Images are standalone executables that can be generated by processing compiled Java applications ahead-of-time. Native Images generally have a smaller memory footprint and start faster than their JVM counterparts.
15.1. Introducing GraalVM Native Images
GraalVM Native Images provide a new way to deploy and run Java applications. Compared to the Java Virtual Machine, native images can run with a smaller memory footprint and with much faster startup times.
They are well suited to applications that are deployed using container images and are especially interesting when combined with "Function as a service" (FaaS) platforms.
Unlike traditional applications written for the JVM, GraalVM Native Image applications require ahead-of-time processing in order to create an executable. This ahead-of-time processing involves statically analyzing your application code from its main entry point.
A GraalVM Native Image is a complete, platform-specific executable. You do not need to ship a Java Virtual Machine in order to run a native image.
If you just want to get started and experiment with GraalVM you can skip ahead to the “Developing Your First GraalVM Native Application” section and return to this section later. |
15.1.1. Key Differences with JVM Deployments
The fact that GraalVM Native Images are produced ahead-of-time means that there are some key differences between native and JVM based applications. The main differences are:
-
Static analysis of your application is performed at build-time from the
main
entry point. -
Code that cannot be reached when the native image is created will be removed and won’t be part of the executable.
-
GraalVM is not directly aware of dynamic elements of your code and must be told about reflection, resources, serialization, and dynamic proxies.
-
The application classpath is fixed at build time and cannot change.
-
There is no lazy class loading, everything shipped in the executables will be loaded in memory on startup.
-
There are some limitations around some aspects of Java applications that are not fully supported.
On top of those differences, Spring uses a process called Spring Ahead-of-Time processing, which imposes further limitations. Please make sure to read at least the beginning of the next section to learn about those.
The Native Image Compatibility Guide section of the GraalVM reference documentation provides more details about GraalVM limitations. |
15.1.2. Understanding Spring Ahead-of-Time Processing
Typical Spring Boot applications are quite dynamic and configuration is performed at runtime. In fact, the concept of Spring Boot auto-configuration depends heavily on reacting to the state of the runtime in order to configure things correctly.
Although it would be possible to tell GraalVM about these dynamic aspects of the application, doing so would undo most of the benefit of static analysis. So instead, when using Spring Boot to create native images, a closed-world is assumed and the dynamic aspects of the application are restricted.
A closed-world assumption implies, besides the limitations created by GraalVM itself, the following restrictions:
-
The beans defined in your application cannot change at runtime, meaning:
-
The Spring
@Profile
annotation and profile-specific configuration have limitations. -
Properties that change if a bean is created are not supported (for example,
@ConditionalOnProperty
and.enable
properties).
-
When these restrictions are in place, it becomes possible for Spring to perform ahead-of-time processing during build-time and generate additional assets that GraalVM can use. A Spring AOT processed application will typically generate:
-
Java source code
-
Bytecode (for dynamic proxies etc)
-
GraalVM JSON hint files:
-
Resource hints (
resource-config.json
) -
Reflection hints (
reflect-config.json
) -
Serialization hints (
serialization-config.json
) -
Java Proxy Hints (
proxy-config.json
) -
JNI Hints (
jni-config.json
)
-
Source Code Generation
Spring applications are composed of Spring Beans. Internally, Spring Framework uses two distinct concepts to manage beans. There are bean instances, which are the actual instances that have been created and can be injected into other beans. There are also bean definitions which are used to define attributes of a bean and how its instance should be created.
If we take a typical @Configuration
class:
@Configuration(proxyBeanMethods = false)
public class MyConfiguration {
@Bean
public MyBean myBean() {
return new MyBean();
}
}
The bean definition is created by parsing the @Configuration
class and finding the @Bean
methods.
In the above example, we’re defining a BeanDefinition
for a singleton bean named myBean
.
We’re also creating a BeanDefinition
for the MyConfiguration
class itself.
When the myBean
instance is required, Spring knows that it must invoke the myBean()
method and use the result.
When running on the JVM, @Configuration
class parsing happens when your application starts and @Bean
methods are invoked using reflection.
When creating a native image, Spring operates in a different way.
Rather than parsing @Configuration
classes and generating bean definitions at runtime, it does it at build-time.
Once the bean definitions have been discovered, they are processed and converted into source code that can be analyzed by the GraalVM compiler.
The Spring AOT process would convert the configuration class above to code like this:
/**
* Bean definitions for {@link MyConfiguration}.
*/
public class MyConfiguration__BeanDefinitions {
/**
* Get the bean definition for 'myConfiguration'.
*/
public static BeanDefinition getMyConfigurationBeanDefinition() {
Class<?> beanType = MyConfiguration.class;
RootBeanDefinition beanDefinition = new RootBeanDefinition(beanType);
beanDefinition.setInstanceSupplier(MyConfiguration::new);
return beanDefinition;
}
/**
* Get the bean instance supplier for 'myBean'.
*/
private static BeanInstanceSupplier<MyBean> getMyBeanInstanceSupplier() {
return BeanInstanceSupplier.<MyBean>forFactoryMethod(MyConfiguration.class, "myBean")
.withGenerator((registeredBean) -> registeredBean.getBeanFactory().getBean(MyConfiguration.class).myBean());
}
/**
* Get the bean definition for 'myBean'.
*/
public static BeanDefinition getMyBeanBeanDefinition() {
Class<?> beanType = MyBean.class;
RootBeanDefinition beanDefinition = new RootBeanDefinition(beanType);
beanDefinition.setInstanceSupplier(getMyBeanInstanceSupplier());
return beanDefinition;
}
}
The exact code generated may differ depending on the nature of your bean definitions. |
You can see above that the generated code creates equivalent bean definitions to the @Configuration
class, but in a direct way that can be understood by GraalVM.
There is a bean definition for the myConfiguration
bean, and one for myBean
.
When a myBean
instance is required, a BeanInstanceSupplier
is called.
This supplier will invoke the myBean()
method on the myConfiguration
bean.
During Spring AOT processing your application is started up to the point that bean definitions are available. Bean instances are not created during the AOT processing phase. |
Spring AOT will generate code like this for all your bean definitions.
It will also generate code when bean post-processing is required (for example, to call @Autowired
methods).
An ApplicationContextInitializer
will also be generated which will be used by Spring Boot to initialize the ApplicationContext
when an AOT processed application is actually run.
Although AOT generated source code can be verbose, it is quite readable and can be helpful when debugging an application.
Generated source files can be found in target/spring-aot/main/sources when using Maven and build/generated/aotSources with Gradle.
|
Hint File Generation
In addition to generating source files, the Spring AOT engine will also generate hint files that are used by GraalVM. Hint files contain JSON data that describes how GraalVM should deal with things that it can’t understand by directly inspecting the code.
For example, you might be using a Spring annotation on a private method. Spring will need to use reflection in order to invoke private methods, even on GraalVM. When such situations arise, Spring can write a reflection hint so that GraalVM knows that even though the private method isn’t called directly, it still needs to be available in the native image.
Hint files are generated under META-INF/native-image
where they are automatically picked up by GraalVM.
Generated hint files can be found in target/spring-aot/main/resources when using Maven and build/generated/aotResources with Gradle.
|
Proxy Class Generation
Spring sometimes needs to generate proxy classes to enhance the code you’ve written with additional features. To do this, it uses the cglib library which directly generates bytecode.
When an application is running on the JVM, proxy classes are generated dynamically as the application runs. When creating a native image, these proxies need to be created at build-time so that they can be included by GraalVM.
Unlike source code generation, generated bytecode isn’t particularly helpful when debugging an application.
However, if you need to inspect the contents of the .class files using a tool such as javap you can find them in target/spring-aot/main/classes for Maven and build/generated/aotClasses for Gradle.
|
15.2. Developing Your First GraalVM Native Application
Now that we have a good overview of GraalVM Native Images and how the Spring ahead-of-time engine works, we can look at how to create an application.
There are two main ways to build a Spring Boot native image application:
-
Using Spring Boot support for Cloud Native Buildpacks to generate a lightweight container containing a native executable.
-
Using GraalVM Native Build Tools to generate a native executable.
The easiest way to start a new native Spring Boot project is to go to start.spring.io, add the “GraalVM Native Support” dependency and generate the project.
The included HELP.md file will provide getting started hints.
|
15.2.1. Sample Application
We need an example application that we can use to create our native image. For our purposes, the simple “Hello World!” web application that’s covered in the “Developing Your First Spring Boot Application” section will suffice.
To recap, our main application code looks like this:
@RestController
@SpringBootApplication
public class MyApplication {
@RequestMapping("/")
String home() {
return "Hello World!";
}
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
This application uses Spring MVC and embedded Tomcat, both of which have been tested and verified to work with GraalVM native images.
15.2.2. Building a Native Image Using Buildpacks
Spring Boot includes buildpack support for native images directly for both Maven and Gradle. This means you can just type a single command and quickly get a sensible image into your locally running Docker daemon. The resulting image doesn’t contain a JVM, instead the native image is compiled statically. This leads to smaller images.
The builder used for the images is paketobuildpacks/builder-jammy-tiny:latest .
It has small footprint and reduced attack surface, but you can also use paketobuildpacks/builder-jammy-base:latest or paketobuildpacks/builder-jammy-full:latest to have more tools available in the image if required.
|
System Requirements
Docker should be installed. See Get Docker for more details. Configure it to allow non-root user if you are on Linux.
You can run docker run hello-world (without sudo ) to check the Docker daemon is reachable as expected.
Check the Maven or Gradle Spring Boot plugin documentation for more details.
|
On macOS, it is recommended to increase the memory allocated to Docker to at least 8GB , and potentially add more CPUs as well.
See this Stack Overflow answer for more details.
On Microsoft Windows, make sure to enable the Docker WSL 2 backend for better performance.
|
Using Maven
To build a native image container using Maven you should ensure that your pom.xml
file uses the spring-boot-starter-parent
and the org.graalvm.buildtools:native-maven-plugin
.
You should have a <parent>
section that looks like this:
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>3.2.0-SNAPSHOT</version>
</parent>
You additionally should have this in the <build> <plugins>
section:
<plugin>
<groupId>org.graalvm.buildtools</groupId>
<artifactId>native-maven-plugin</artifactId>
</plugin>
The spring-boot-starter-parent
declares a native
profile that configures the executions that need to run in order to create a native image.
You can activate profiles using the -P
flag on the command line.
If you don’t want to use spring-boot-starter-parent you’ll need to configure executions for the process-aot goal from Spring Boot’s plugin and the add-reachability-metadata goal from the Native Build Tools plugin.
|
To build the image, you can run the spring-boot:build-image
goal with the native
profile active:
$ mvn -Pnative spring-boot:build-image
Using Gradle
The Spring Boot Gradle plugin automatically configures AOT tasks when the GraalVM Native Image plugin is applied.
You should check that your Gradle build contains a plugins
block that includes org.graalvm.buildtools.native
.
As long as the org.graalvm.buildtools.native
plugin is applied, the bootBuildImage
task will generate a native image rather than a JVM one.
You can run the task using:
$ gradle bootBuildImage
Running the example
Once you have run the appropriate build command, a Docker image should be available.
You can start your application using docker run
:
$ docker run --rm -p 8080:8080 docker.io/library/myproject:0.0.1-SNAPSHOT
You should see output similar to the following:
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v3.2.0-SNAPSHOT)
....... . . .
....... . . . (log output here)
....... . . .
........ Started MyApplication in 0.08 seconds (process running for 0.095)
The startup time differs from machine to machine, but it should be much faster than a Spring Boot application running on a JVM. |
If you open a web browser to localhost:8080
, you should see the following output:
Hello World!
To gracefully exit the application, press ctrl-c
.
15.2.3. Building a Native Image using Native Build Tools
If you want to generate a native executable directly without using Docker, you can use GraalVM Native Build Tools. Native Build Tools are plugins shipped by GraalVM for both Maven and Gradle. You can use them to perform a variety of GraalVM tasks, including generating a native image.
Prerequisites
To build a native image using the Native Build Tools, you’ll need a GraalVM distribution on your machine. You can either download it manually on the Liberica Native Image Kit page, or you can use a download manager like SDKMAN!.
Linux and macOS
To install the native image compiler on macOS or Linux, we recommend using SDKMAN!. Get SDKMAN! from sdkman.io and install the Liberica GraalVM distribution by using the following commands:
$ sdk install java 22.3.r17-nik
$ sdk use java 22.3.r17-nik
Verify that the correct version has been configured by checking the output of java -version
:
$ java -version
openjdk version "17.0.5" 2022-10-18 LTS
OpenJDK Runtime Environment GraalVM 22.3.0 (build 17.0.5+8-LTS)
OpenJDK 64-Bit Server VM GraalVM 22.3.0 (build 17.0.5+8-LTS, mixed mode)
Windows
On Windows, follow these instructions to install either GraalVM or Liberica Native Image Kit in version 22.3, the Visual Studio Build Tools and the Windows SDK. Due to the Windows related command-line maximum length, make sure to use x64 Native Tools Command Prompt instead of the regular Windows command line to run Maven or Gradle plugins.
Using Maven
As with the buildpack support, you need to make sure that you’re using spring-boot-starter-parent
in order to inherit the native
profile and that the org.graalvm.buildtools:native-maven-plugin
plugin is used.
With the native
profile active, you can invoke the native:compile
goal to trigger native-image
compilation:
$ mvn -Pnative native:compile
The native image executable can be found in the target
directory.
Using Gradle
When the Native Build Tools Gradle plugin is applied to your project, the Spring Boot Gradle plugin will automatically trigger the Spring AOT engine.
Task dependencies are automatically configured, so you can just run the standard nativeCompile
task to generate a native image:
$ gradle nativeCompile
The native image executable can be found in the build/native/nativeCompile
directory.
Running the Example
At this point, your application should work. You can now start the application by running it directly:
$ target/myproject
$ build/native/nativeCompile/myproject
You should see output similar to the following:
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v3.2.0-SNAPSHOT)
....... . . .
....... . . . (log output here)
....... . . .
........ Started MyApplication in 0.08 seconds (process running for 0.095)
The startup time differs from machine to machine, but it should be much faster than a Spring Boot application running on a JVM. |
If you open a web browser to localhost:8080
, you should see the following output:
Hello World!
To gracefully exit the application, press ctrl-c
.
15.3. Testing GraalVM Native Images
When writing native image applications, we recommend that you continue to use the JVM whenever possible to develop the majority of your unit and integration tests. This will help keep developer build times down and allow you to use existing IDE integrations. With broad test coverage on the JVM, you can then focus native image testing on the areas that are likely to be different.
For native image testing, you’re generally looking to ensure that the following aspects work:
-
The Spring AOT engine is able to process your application, and it will run in an AOT-processed mode.
-
GraalVM has enough hints to ensure that a valid native image can be produced.
15.3.1. Testing Ahead-of-time Processing With the JVM
When a Spring Boot application runs, it attempts to detect if it is running as a native image. If it is running as a native image, it will initialize the application using the code that was generated during at build-time by the Spring AOT engine.
If the application is running on a regular JVM, then any AOT generated code is ignored.
Since the native-image
compilation phase can take a while to complete, it’s sometimes useful to run your application on the JVM but have it use the AOT generated initialization code.
Doing so helps you to quickly validate that there are no errors in the AOT generated code and nothing is missing when your application is eventually converted to a native image.
To run a Spring Boot application on the JVM and have it use AOT generated code you can set the spring.aot.enabled
system property to true
.
For example:
$ java -Dspring.aot.enabled=true -jar myapplication.jar
You need to ensure that the jar you are testing includes AOT generated code.
For Maven, this means that you should build with -Pnative to activate the native profile.
For Gradle, you need to ensure that your build includes the org.graalvm.buildtools.native plugin.
|
If your application starts with the spring.aot.enabled
property set to true
, then you have higher confidence that it will work when converted to a native image.
You can also consider running integration tests against the running application.
For example, you could use the Spring WebClient
to call your application REST endpoints.
Or you might consider using a project like Selenium to check your application’s HTML responses.
15.3.2. Testing With Native Build Tools
GraalVM Native Build Tools includes the ability to run tests inside a native image. This can be helpful when you want to deeply test that the internals of your application work in a GraalVM native image.
Generating the native image that contains the tests to run can be a time-consuming operation, so most developers will probably prefer to use the JVM locally. They can, however, be very useful as part of a CI pipeline. For example, you might choose to run native tests once a day.
Spring Framework includes ahead-of-time support for running tests.
All the usual Spring testing features work with native image tests.
For example, you can continue to use the @SpringBootTest
annotation.
You can also use Spring Boot test slices to test only specific parts of your application.
Spring Framework’s native testing support works in the following way:
-
Tests are analyzed in order to discover any
ApplicationContext
instances that will be required. -
Ahead-of-time processing is applied to each of these application contexts and assets are generated.
-
A native image is created, with the generated assets being processed by GraalVM.
-
The native image also includes the JUnit
TestEngine
configured with a list of the discovered tests. -
The native image is started, triggering the engine which will run each test and report results.
Using Maven
To run native tests using Maven, ensure that your pom.xml
file uses the spring-boot-starter-parent
.
You should have a <parent>
section that looks like this:
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>3.2.0-SNAPSHOT</version>
</parent>
The spring-boot-starter-parent
declares a nativeTest
profile that configures the executions that are needed to run the native tests.
You can activate profiles using the -P
flag on the command line.
If you don’t want to use spring-boot-starter-parent you’ll need to configure executions for the process-test-aot goal from the Spring Boot plugin and the test goal from the Native Build Tools plugin.
|
To build the image and run the tests, use the test
goal with the nativeTest
profile active:
$ mvn -PnativeTest test
Using Gradle
The Spring Boot Gradle plugin automatically configures AOT test tasks when the GraalVM Native Image plugin is applied.
You should check that your Gradle build contains a plugins
block that includes org.graalvm.buildtools.native
.
To run native tests using Gradle you can use the nativeTest
task:
$ gradle nativeTest
15.4. Advanced Native Images Topics
15.4.1. Nested Configuration Properties
Reflection hints are automatically created for configuration properties by the Spring ahead-of-time engine.
Nested configuration properties which are not inner classes, however, must be annotated with @NestedConfigurationProperty
, otherwise they won’t be detected and will not be bindable.
@ConfigurationProperties(prefix = "my.properties")
public class MyProperties {
private String name;
@NestedConfigurationProperty
private final Nested nested = new Nested();
}
where Nested
is:
public class Nested {
private int number;
}
The example above produces configuration properties for my.properties.name
and my.properties.nested.number
.
Without the @NestedConfigurationProperty
annotation on the nested
field, the my.properties.nested.number
property would not be bindable in a native image.
When using constructor binding, you have to annotate the field with @NestedConfigurationProperty
:
@ConfigurationProperties(prefix = "my.properties")
public class MyPropertiesCtor {
private final String name;
@NestedConfigurationProperty
private final Nested nested;
public MyPropertiesCtor(String name, Nested nested) {
this.name = name;
this.nested = nested;
}
}
When using records, you have to annotate the parameter with @NestedConfigurationProperty
:
@ConfigurationProperties(prefix = "my.properties")
public record MyPropertiesRecord(String name, @NestedConfigurationProperty Nested nested) {
}
When using Kotlin, you need to annotate the parameter of a data class with @NestedConfigurationProperty
:
@ConfigurationProperties(prefix = "my.properties")
data class MyPropertiesKotlin(
val name: String,
@NestedConfigurationProperty val nested: Nested
)
Please use public getters and setters in all cases, otherwise the properties will not be bindable. |
15.4.2. Converting a Spring Boot Executable Jar
It is possible to convert a Spring Boot executable jar into a native image as long as the jar contains the AOT generated assets. This can be useful for a number of reasons, including:
-
You can keep your regular JVM pipeline and turn the JVM application into a native image on your CI/CD platform.
-
As
native-image
does not support cross-compilation, you can keep an OS neutral deployment artifact which you convert later to different OS architectures.
You can convert a Spring Boot executable jar into a native image using Cloud Native Buildpacks, or using the native-image
tool that is shipped with GraalVM.
Your executable jar must include AOT generated assets such as generated classes and JSON hint files. |
Using Buildpacks
Spring Boot applications usually use Cloud Native Buildpacks through the Maven (mvn spring-boot:build-image
) or Gradle (gradle bootBuildImage
) integrations.
You can, however, also use pack
to turn an AOT processed Spring Boot executable jar into a native container image.
First, make sure that a Docker daemon is available (see Get Docker for more details). Configure it to allow non-root user if you are on Linux.
You also need to install pack
by following the installation guide on buildpacks.io.
Assuming an AOT processed Spring Boot executable jar built as myproject-0.0.1-SNAPSHOT.jar
is in the target
directory, run:
$ pack build --builder paketobuildpacks/builder-jammy-tiny \
--path target/myproject-0.0.1-SNAPSHOT.jar \
--env 'BP_NATIVE_IMAGE=true' \
my-application:0.0.1-SNAPSHOT
You do not need to have a local GraalVM installation to generate an image in this way. |
Once pack
has finished, you can launch the application using docker run
:
$ docker run --rm -p 8080:8080 docker.io/library/myproject:0.0.1-SNAPSHOT
Using GraalVM native-image
Another option to turn an AOT processed Spring Boot executable jar into a native executable is to use the GraalVM native-image
tool.
For this to work, you’ll need a GraalVM distribution on your machine.
You can either download it manually on the Liberica Native Image Kit page or you can use a download manager like SDKMAN!.
Assuming an AOT processed Spring Boot executable jar built as myproject-0.0.1-SNAPSHOT.jar
is in the target
directory, run:
$ rm -rf target/native
$ mkdir -p target/native
$ cd target/native
$ jar -xvf ../myproject-0.0.1-SNAPSHOT.jar
$ native-image -H:Name=myproject @META-INF/native-image/argfile -cp .:BOOT-INF/classes:`find BOOT-INF/lib | tr '\n' ':'`
$ mv myproject ../
These commands work on Linux or macOS machines, but you will need to adapt them for Windows. |
The @META-INF/native-image/argfile might not be packaged in your jar.
It is only included when reachability metadata overrides are needed.
|
The native-image -cp flag does not accept wildcards.
You need to ensure that all jars are listed (the command above uses find and tr to do this).
|
15.4.3. Using the Tracing Agent
The GraalVM native image tracing agent allows you to intercept reflection, resources or proxy usage on the JVM in order to generate the related hints. Spring should generate most of these hints automatically, but the tracing agent can be used to quickly identify the missing entries.
When using the agent to generate hints for a native image, there are a couple of approaches:
-
Launch the application directly and exercise it.
-
Run application tests to exercise the application.
The first option is interesting for identifying the missing hints when a library or a pattern is not recognized by Spring.
The second option sounds more appealing for a repeatable setup, but by default the generated hints will include anything required by the test infrastructure. Some of these will be unnecessary when the application runs for real. To address this problem the agent supports an access-filter file that will cause certain data to be excluded from the generated output.
Launch the Application Directly
Use the following command to launch the application with the native image tracing agent attached:
$ java -Dspring.aot.enabled=true \
-agentlib:native-image-agent=config-output-dir=/path/to/config-dir/ \
-jar target/myproject-0.0.1-SNAPSHOT.jar
Now you can exercise the code paths you want to have hints for and then stop the application with ctrl-c
.
On application shutdown the native image tracing agent will write the hint files to the given config output directory.
You can either manually inspect these files, or use them as input to the native image build process.
To use them as input, copy them into the src/main/resources/META-INF/native-image/
directory.
The next time you build the native image, GraalVM will take these files into consideration.
There are more advanced options which can be set on the native image tracing agent, for example filtering the recorded hints by caller classes, etc. For further reading, please see the official documentation.
15.4.4. Custom Hints
If you need to provide your own hints for reflection, resources, serialization, proxy usage etc. you can use the RuntimeHintsRegistrar
API.
Create a class that implements the RuntimeHintsRegistrar
interface, and then make appropriate calls to the provided RuntimeHints
instance:
public class MyRuntimeHints implements RuntimeHintsRegistrar {
@Override
public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
// Register method for reflection
Method method = ReflectionUtils.findMethod(MyClass.class, "sayHello", String.class);
hints.reflection().registerMethod(method, ExecutableMode.INVOKE);
// Register resources
hints.resources().registerPattern("my-resource.txt");
// Register serialization
hints.serialization().registerType(MySerializableClass.class);
// Register proxy
hints.proxies().registerJdkProxy(MyInterface.class);
}
}
You can then use @ImportRuntimeHints
on any @Configuration
class (for example your @SpringBootApplication
annotated application class) to activate those hints.
If you have classes which need binding (mostly needed when serializing or deserializing JSON), you can use @RegisterReflectionForBinding
on any bean.
Most of the hints are automatically inferred, for example when accepting or returning data from a @RestController
method.
But when you work with WebClient
, RestClient
or RestTemplate
directly, you might need to use @RegisterReflectionForBinding
.
Testing custom hints
The RuntimeHintsPredicates
API can be used to test your hints.
The API provides methods that build a Predicate
that can be used to test a RuntimeHints
instance.
If you’re using AssertJ, your test would look like this:
class MyRuntimeHintsTests {
@Test
void shouldRegisterHints() {
RuntimeHints hints = new RuntimeHints();
new MyRuntimeHints().registerHints(hints, getClass().getClassLoader());
assertThat(RuntimeHintsPredicates.resource().forResource("my-resource.txt")).accepts(hints);
}
}
15.4.5. Known Limitations
GraalVM native images are an evolving technology and not all libraries provide support. The GraalVM community is helping by providing reachability metadata for projects that don’t yet ship their own. Spring itself doesn’t contain hints for 3rd party libraries and instead relies on the reachability metadata project.
If you encounter problems when generating native images for Spring Boot applications, please check the Spring Boot with GraalVM page of the Spring Boot wiki. You can also contribute issues to the spring-aot-smoke-tests project on GitHub which is used to confirm that common application types are working as expected.
If you find a library which doesn’t work with GraalVM, please raise an issue on the reachability metadata project.
15.5. What to Read Next
If you want to learn more about the ahead-of-time processing provided by our build plugins, see the Maven and Gradle plugin documentation.
To learn more about the APIs used to perform the processing, browse the org.springframework.aot.generate
and org.springframework.beans.factory.aot
packages of the Spring Framework sources.
For known limitations with Spring and GraalVM, please see the Spring Boot wiki.
The next section goes on to cover the Spring Boot CLI.
16. Spring Boot CLI
The Spring Boot CLI is a command line tool that you can use to bootstrap a new project from start.spring.io or encode a password.
16.1. Installing the CLI
The Spring Boot CLI (Command-Line Interface) can be installed manually by using SDKMAN! (the SDK Manager) or by using Homebrew or MacPorts if you are an OSX user. See Installing the Spring Boot CLI in the “Getting started” section for comprehensive installation instructions.
16.2. Using the CLI
Once you have installed the CLI, you can run it by typing spring
and pressing Enter at the command line.
If you run spring
without any arguments, a help screen is displayed, as follows:
$ spring
usage: spring [--help] [--version]
<command> [<args>]
Available commands are:
init [options] [location]
Initialize a new project using Spring Initializr (start.spring.io)
encodepassword [options] <password to encode>
Encode a password for use with Spring Security
shell
Start a nested shell
Common options:
--debug Verbose mode
Print additional status information for the command you are running
See 'spring help <command>' for more information on a specific command.
You can type spring help
to get more details about any of the supported commands, as shown in the following example:
$ spring help init
spring init - Initialize a new project using Spring Initializr (start.spring.io)
usage: spring init [options] [location]
Option Description
------ -----------
-a, --artifact-id <String> Project coordinates; infer archive name (for
example 'test')
-b, --boot-version <String> Spring Boot version (for example '1.2.0.RELEASE')
--build <String> Build system to use (for example 'maven' or
'gradle') (default: maven)
-d, --dependencies <String> Comma-separated list of dependency identifiers to
include in the generated project
--description <String> Project description
-f, --force Force overwrite of existing files
--format <String> Format of the generated content (for example
'build' for a build file, 'project' for a
project archive) (default: project)
-g, --group-id <String> Project coordinates (for example 'org.test')
-j, --java-version <String> Language level (for example '1.8')
-l, --language <String> Programming language (for example 'java')
--list List the capabilities of the service. Use it to
discover the dependencies and the types that are
available
-n, --name <String> Project name; infer application name
-p, --packaging <String> Project packaging (for example 'jar')
--package-name <String> Package name
-t, --type <String> Project type. Not normally needed if you use --
build and/or --format. Check the capabilities of
the service (--list) for more details
--target <String> URL of the service to use (default: https://start.
spring.io)
-v, --version <String> Project version (for example '0.0.1-SNAPSHOT')
-x, --extract Extract the project archive. Inferred if a
location is specified without an extension
examples:
To list all the capabilities of the service:
$ spring init --list
To creates a default project:
$ spring init
To create a web my-app.zip:
$ spring init -d=web my-app.zip
To create a web/data-jpa gradle project unpacked:
$ spring init -d=web,jpa --build=gradle my-dir
The version
command provides a quick way to check which version of Spring Boot you are using, as follows:
$ spring version
Spring CLI v3.2.0-SNAPSHOT
16.2.1. Initialize a New Project
The init
command lets you create a new project by using start.spring.io without leaving the shell, as shown in the following example:
$ spring init --dependencies=web,data-jpa my-project
Using service at https://start.spring.io
Project extracted to '/Users/developer/example/my-project'
The preceding example creates a my-project
directory with a Maven-based project that uses spring-boot-starter-web
and spring-boot-starter-data-jpa
.
You can list the capabilities of the service by using the --list
flag, as shown in the following example:
$ spring init --list
=======================================
Capabilities of https://start.spring.io
=======================================
Available dependencies:
-----------------------
actuator - Actuator: Production ready features to help you monitor and manage your application
...
web - Web: Support for full-stack web development, including Tomcat and spring-webmvc
websocket - Websocket: Support for WebSocket development
ws - WS: Support for Spring Web Services
Available project types:
------------------------
gradle-build - Gradle Config [format:build, build:gradle]
gradle-project - Gradle Project [format:project, build:gradle]
maven-build - Maven POM [format:build, build:maven]
maven-project - Maven Project [format:project, build:maven] (default)
...
The init
command supports many options.
See the help
output for more details.
For instance, the following command creates a Gradle project that uses Java 17 and war
packaging:
$ spring init --build=gradle --java-version=17 --dependencies=websocket --packaging=war sample-app.zip
Using service at https://start.spring.io
Content saved to 'sample-app.zip'
16.2.2. Using the Embedded Shell
Spring Boot includes command-line completion scripts for the BASH and zsh shells.
If you do not use either of these shells (perhaps you are a Windows user), you can use the shell
command to launch an integrated shell, as shown in the following example:
$ spring shell
Spring Boot (v3.2.0-SNAPSHOT)
Hit TAB to complete. Type \'help' and hit RETURN for help, and \'exit' to quit.
From inside the embedded shell, you can run other commands directly:
$ version
Spring CLI v3.2.0-SNAPSHOT
The embedded shell supports ANSI color output as well as tab
completion.
If you need to run a native command, you can use the !
prefix.
To exit the embedded shell, press ctrl-c
.
17. Build Tool Plugins
Spring Boot provides build tool plugins for Maven and Gradle. The plugins offer a variety of features, including the packaging of executable jars. This section provides more details on both plugins as well as some help should you need to extend an unsupported build system. If you are just getting started, you might want to read “Build Systems” from the “Developing with Spring Boot” section first.
17.1. Spring Boot Maven Plugin
The Spring Boot Maven Plugin provides Spring Boot support in Maven, letting you package executable jar or war archives and run an application “in-place”. To use it, you must use Maven 3.6.3 or later.
See the plugin’s documentation to learn more:
17.2. Spring Boot Gradle Plugin
The Spring Boot Gradle Plugin provides Spring Boot support in Gradle, letting you package executable jar or war archives, run Spring Boot applications, and use the dependency management provided by spring-boot-dependencies
.
It requires Gradle 7.x (7.5 or later) or 8.x.
See the plugin’s documentation to learn more:
17.3. Spring Boot AntLib Module
The Spring Boot AntLib module provides basic Spring Boot support for Apache Ant.
You can use the module to create executable jars.
To use the module, you need to declare an additional spring-boot
namespace in your build.xml
, as shown in the following example:
<project xmlns:ivy="antlib:org.apache.ivy.ant"
xmlns:spring-boot="antlib:org.springframework.boot.ant"
name="myapp" default="build">
...
</project>
You need to remember to start Ant using the -lib
option, as shown in the following example:
$ ant -lib <directory containing spring-boot-antlib-3.2.0-SNAPSHOT.jar>
The “Using Spring Boot” section includes a more complete example of using Apache Ant with spring-boot-antlib .
|
17.3.1. Spring Boot Ant Tasks
Once the spring-boot-antlib
namespace has been declared, the following additional tasks are available:
Using the “exejar” Task
You can use the exejar
task to create a Spring Boot executable jar.
The following attributes are supported by the task:
Attribute | Description | Required |
---|---|---|
|
The destination jar file to create |
Yes |
|
The root directory of Java class files |
Yes |
|
The main application class to run |
No (the default is the first class found that declares a |
The following nested elements can be used with the task:
Element | Description |
---|---|
|
One or more Resource Collections describing a set of Resources that should be added to the content of the created jar file. |
|
One or more Resource Collections that should be added to the set of jar libraries that make up the runtime dependency classpath of the application. |
Examples
This section shows two examples of Ant tasks.
<spring-boot:exejar destfile="target/my-application.jar"
classes="target/classes" start-class="com.example.MyApplication">
<resources>
<fileset dir="src/main/resources" />
</resources>
<lib>
<fileset dir="lib" />
</lib>
</spring-boot:exejar>
<exejar destfile="target/my-application.jar" classes="target/classes">
<lib>
<fileset dir="lib" />
</lib>
</exejar>
17.3.2. Using the “findmainclass” Task
The findmainclass
task is used internally by exejar
to locate a class declaring a main
.
If necessary, you can also use this task directly in your build.
The following attributes are supported:
Attribute | Description | Required |
---|---|---|
|
The root directory of Java class files |
Yes (unless |
|
Can be used to short-circuit the |
No |
|
The Ant property that should be set with the result |
No (result will be logged if unspecified) |
Examples
This section contains three examples of using findmainclass
.
<findmainclass classesroot="target/classes" />
<findmainclass classesroot="target/classes" property="main-class" />
<findmainclass mainclass="com.example.MainClass" property="main-class" />
17.4. Supporting Other Build Systems
If you want to use a build tool other than Maven, Gradle, or Ant, you likely need to develop your own plugin. Executable jars need to follow a specific format and certain entries need to be written in an uncompressed form (see the “executable jar format” section in the appendix for details).
The Spring Boot Maven and Gradle plugins both make use of spring-boot-loader-tools
to actually generate jars.
If you need to, you may use this library directly.
17.4.1. Repackaging Archives
To repackage an existing archive so that it becomes a self-contained executable archive, use org.springframework.boot.loader.tools.Repackager
.
The Repackager
class takes a single constructor argument that refers to an existing jar or war archive.
Use one of the two available repackage()
methods to either replace the original file or write to a new destination.
Various settings can also be configured on the repackager before it is run.
17.4.2. Nested Libraries
When repackaging an archive, you can include references to dependency files by using the org.springframework.boot.loader.tools.Libraries
interface.
We do not provide any concrete implementations of Libraries
here as they are usually build-system-specific.
If your archive already includes libraries, you can use Libraries.NONE
.
17.4.3. Finding a Main Class
If you do not use Repackager.setMainClass()
to specify a main class, the repackager uses ASM to read class files and tries to find a suitable class with a public static void main(String[] args)
method.
An exception is thrown if more than one candidate is found.
17.4.4. Example Repackage Implementation
The following example shows a typical repackage implementation:
public class MyBuildTool {
public void build() throws IOException {
File sourceJarFile = ...
Repackager repackager = new Repackager(sourceJarFile);
repackager.setBackupSource(false);
repackager.repackage(this::getLibraries);
}
private void getLibraries(LibraryCallback callback) throws IOException {
// Build system specific implementation, callback for each dependency
for (File nestedJar : getCompileScopeJars()) {
callback.library(new Library(nestedJar, LibraryScope.COMPILE));
}
// ...
}
private List<File> getCompileScopeJars() {
return ...
}
}
class MyBuildTool {
@Throws(IOException::class)
fun build() {
val sourceJarFile: File? = ...
val repackager = Repackager(sourceJarFile)
repackager.setBackupSource(false)
repackager.repackage { callback: LibraryCallback -> getLibraries(callback) }
}
@Throws(IOException::class)
private fun getLibraries(callback: LibraryCallback) {
// Build system specific implementation, callback for each dependency
for (nestedJar in getCompileScopeJars()!!) {
callback.library(Library(nestedJar, LibraryScope.COMPILE))
}
// ...
}
private fun getCompileScopeJars(): List<File?>? {
return ...
}
}
17.5. What to Read Next
If you are interested in how the build tool plugins work, you can look at the spring-boot-tools
module on GitHub.
More technical details of the executable jar format are covered in the appendix.
If you have specific build-related questions, see the “how-to” guides.
18. “How-to” Guides
This section provides answers to some common ‘how do I do that…’ questions that often arise when using Spring Boot. Its coverage is not exhaustive, but it does cover quite a lot.
If you have a specific problem that we do not cover here, you might want to check stackoverflow.com to see if someone has already provided an answer.
This is also a great place to ask new questions (please use the spring-boot
tag).
We are also more than happy to extend this section. If you want to add a ‘how-to’, send us a pull request.
18.1. Spring Boot Application
This section includes topics relating directly to Spring Boot applications.
18.1.1. Create Your Own FailureAnalyzer
FailureAnalyzer
is a great way to intercept an exception on startup and turn it into a human-readable message, wrapped in a FailureAnalysis
.
Spring Boot provides such an analyzer for application-context-related exceptions, JSR-303 validations, and more.
You can also create your own.
AbstractFailureAnalyzer
is a convenient extension of FailureAnalyzer
that checks the presence of a specified exception type in the exception to handle.
You can extend from that so that your implementation gets a chance to handle the exception only when it is actually present.
If, for whatever reason, you cannot handle the exception, return null
to give another implementation a chance to handle the exception.
FailureAnalyzer
implementations must be registered in META-INF/spring.factories
.
The following example registers ProjectConstraintViolationFailureAnalyzer
:
org.springframework.boot.diagnostics.FailureAnalyzer=\
com.example.ProjectConstraintViolationFailureAnalyzer
If you need access to the BeanFactory or the Environment , your FailureAnalyzer can implement BeanFactoryAware or EnvironmentAware respectively.
|
18.1.2. Troubleshoot Auto-configuration
The Spring Boot auto-configuration tries its best to “do the right thing”, but sometimes things fail, and it can be hard to tell why.
There is a really useful ConditionEvaluationReport
available in any Spring Boot ApplicationContext
.
You can see it if you enable DEBUG
logging output.
If you use the spring-boot-actuator
(see the Actuator chapter), there is also a conditions
endpoint that renders the report in JSON.
Use that endpoint to debug the application and see what features have been added (and which have not been added) by Spring Boot at runtime.
Many more questions can be answered by looking at the source code and the Javadoc. When reading the code, remember the following rules of thumb:
-
Look for classes called
*AutoConfiguration
and read their sources. Pay special attention to the@Conditional*
annotations to find out what features they enable and when. Add--debug
to the command line or a System property-Ddebug
to get a log on the console of all the auto-configuration decisions that were made in your app. In a running application with actuator enabled, look at theconditions
endpoint (/actuator/conditions
or the JMX equivalent) for the same information. -
Look for classes that are
@ConfigurationProperties
(such asServerProperties
) and read from there the available external configuration options. The@ConfigurationProperties
annotation has aname
attribute that acts as a prefix to external properties. Thus,ServerProperties
hasprefix="server"
and its configuration properties areserver.port
,server.address
, and others. In a running application with actuator enabled, look at theconfigprops
endpoint. -
Look for uses of the
bind
method on theBinder
to pull configuration values explicitly out of theEnvironment
in a relaxed manner. It is often used with a prefix. -
Look for
@Value
annotations that bind directly to theEnvironment
. -
Look for
@ConditionalOnExpression
annotations that switch features on and off in response to SpEL expressions, normally evaluated with placeholders resolved from theEnvironment
.
18.1.3. Customize the Environment or ApplicationContext Before It Starts
A SpringApplication
has ApplicationListeners
and ApplicationContextInitializers
that are used to apply customizations to the context or environment.
Spring Boot loads a number of such customizations for use internally from META-INF/spring.factories
.
There is more than one way to register additional customizations:
-
Programmatically, per application, by calling the
addListeners
andaddInitializers
methods onSpringApplication
before you run it. -
Declaratively, for all applications, by adding a
META-INF/spring.factories
and packaging a jar file that the applications all use as a library.
The SpringApplication
sends some special ApplicationEvents
to the listeners (some even before the context is created) and then registers the listeners for events published by the ApplicationContext
as well.
See “Application Events and Listeners” in the ‘Spring Boot features’ section for a complete list.
It is also possible to customize the Environment
before the application context is refreshed by using EnvironmentPostProcessor
.
Each implementation should be registered in META-INF/spring.factories
, as shown in the following example:
org.springframework.boot.env.EnvironmentPostProcessor=com.example.YourEnvironmentPostProcessor
The implementation can load arbitrary files and add them to the Environment
.
For instance, the following example loads a YAML configuration file from the classpath:
public class MyEnvironmentPostProcessor implements EnvironmentPostProcessor {
private final YamlPropertySourceLoader loader = new YamlPropertySourceLoader();
@Override
public void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {
Resource path = new ClassPathResource("com/example/myapp/config.yml");
PropertySource<?> propertySource = loadYaml(path);
environment.getPropertySources().addLast(propertySource);
}
private PropertySource<?> loadYaml(Resource path) {
Assert.isTrue(path.exists(), () -> "Resource " + path + " does not exist");
try {
return this.loader.load("custom-resource", path).get(0);
}
catch (IOException ex) {
throw new IllegalStateException("Failed to load yaml configuration from " + path, ex);
}
}
}
class MyEnvironmentPostProcessor : EnvironmentPostProcessor {
private val loader = YamlPropertySourceLoader()
override fun postProcessEnvironment(environment: ConfigurableEnvironment, application: SpringApplication) {
val path: Resource = ClassPathResource("com/example/myapp/config.yml")
val propertySource = loadYaml(path)
environment.propertySources.addLast(propertySource)
}
private fun loadYaml(path: Resource): PropertySource<*> {
Assert.isTrue(path.exists()) { "Resource $path does not exist" }
return try {
loader.load("custom-resource", path)[0]
} catch (ex: IOException) {
throw IllegalStateException("Failed to load yaml configuration from $path", ex)
}
}
}
The Environment has already been prepared with all the usual property sources that Spring Boot loads by default.
It is therefore possible to get the location of the file from the environment.
The preceding example adds the custom-resource property source at the end of the list so that a key defined in any of the usual other locations takes precedence.
A custom implementation may define another order.
|
While using @PropertySource on your @SpringBootApplication may seem to be a convenient way to load a custom resource in the Environment , we do not recommend it.
Such property sources are not added to the Environment until the application context is being refreshed.
This is too late to configure certain properties such as logging.* and spring.main.* which are read before refresh begins.
|
18.1.4. Build an ApplicationContext Hierarchy (Adding a Parent or Root Context)
You can use the ApplicationBuilder
class to create parent/child ApplicationContext
hierarchies.
See “Fluent Builder API” in the ‘Spring Boot features’ section for more information.
18.1.5. Create a Non-web Application
Not all Spring applications have to be web applications (or web services).
If you want to execute some code in a main
method but also bootstrap a Spring application to set up the infrastructure to use, you can use the SpringApplication
features of Spring Boot.
A SpringApplication
changes its ApplicationContext
class, depending on whether it thinks it needs a web application or not.
The first thing you can do to help it is to leave server-related dependencies (such as the servlet API) off the classpath.
If you cannot do that (for example, you run two applications from the same code base) then you can explicitly call setWebApplicationType(WebApplicationType.NONE)
on your SpringApplication
instance or set the applicationContextClass
property (through the Java API or with external properties).
Application code that you want to run as your business logic can be implemented as a CommandLineRunner
and dropped into the context as a @Bean
definition.
18.2. Properties and Configuration
This section includes topics about setting and reading properties and configuration settings and their interaction with Spring Boot applications.
18.2.1. Automatically Expand Properties at Build Time
Rather than hardcoding some properties that are also specified in your project’s build configuration, you can automatically expand them by instead using the existing build configuration. This is possible in both Maven and Gradle.
Automatic Property Expansion Using Maven
You can automatically expand properties from the Maven project by using resource filtering.
If you use the spring-boot-starter-parent
, you can then refer to your Maven ‘project properties’ with @..@
placeholders, as shown in the following example:
app:
encoding: "@project.build.sourceEncoding@"
java:
version: "@java.version@"
Only production configuration is filtered that way (in other words, no filtering is applied on src/test/resources ).
|
If you enable the addResources flag, the spring-boot:run goal can add src/main/resources directly to the classpath (for hot reloading purposes).
Doing so circumvents the resource filtering and this feature.
Instead, you can use the exec:java goal or customize the plugin’s configuration.
See the plugin usage page for more details.
|
If you do not use the starter parent, you need to include the following element inside the <build/>
element of your pom.xml
:
<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
</resource>
</resources>
You also need to include the following element inside <plugins/>
:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-resources-plugin</artifactId>
<version>2.7</version>
<configuration>
<delimiters>
<delimiter>@</delimiter>
</delimiters>
<useDefaultDelimiters>false</useDefaultDelimiters>
</configuration>
</plugin>
The useDefaultDelimiters property is important if you use standard Spring placeholders (such as ${placeholder} ) in your configuration.
If that property is not set to false , these may be expanded by the build.
|
Automatic Property Expansion Using Gradle
You can automatically expand properties from the Gradle project by configuring the Java plugin’s processResources
task to do so, as shown in the following example:
tasks.named('processResources') {
expand(project.properties)
}
You can then refer to your Gradle project’s properties by using placeholders, as shown in the following example:
app.name=${name}
app.description=${description}
app:
name: "${name}"
description: "${description}"
Gradle’s expand method uses Groovy’s SimpleTemplateEngine , which transforms ${..} tokens.
The ${..} style conflicts with Spring’s own property placeholder mechanism.
To use Spring property placeholders together with automatic expansion, escape the Spring property placeholders as follows: \${..} .
|
18.2.2. Externalize the Configuration of SpringApplication
A SpringApplication
has bean property setters, so you can use its Java API as you create the application to modify its behavior.
Alternatively, you can externalize the configuration by setting properties in spring.main.*
.
For example, in application.properties
, you might have the following settings:
spring.main.web-application-type=none
spring.main.banner-mode=off
spring:
main:
web-application-type: "none"
banner-mode: "off"
Then the Spring Boot banner is not printed on startup, and the application is not starting an embedded web server.
Properties defined in external configuration override and replace the values specified with the Java API, with the notable exception of the primary sources.
Primary sources are those provided to the SpringApplication
constructor:
@SpringBootApplication
public class MyApplication {
public static void main(String[] args) {
SpringApplication application = new SpringApplication(MyApplication.class);
application.setBannerMode(Banner.Mode.OFF);
application.run(args);
}
}
@SpringBootApplication
object MyApplication {
@JvmStatic
fun main(args: Array<String>) {
val application = SpringApplication(MyApplication::class.java)
application.setBannerMode(Banner.Mode.OFF)
application.run(*args)
}
}
Or to sources(…)
method of a SpringApplicationBuilder
:
public class MyApplication {
public static void main(String[] args) {
new SpringApplicationBuilder()
.bannerMode(Banner.Mode.OFF)
.sources(MyApplication.class)
.run(args);
}
}
object MyApplication {
@JvmStatic
fun main(args: Array<String>) {
SpringApplicationBuilder()
.bannerMode(Banner.Mode.OFF)
.sources(MyApplication::class.java)
.run(*args)
}
}
Given the examples above, if we have the following configuration:
spring.main.sources=com.example.MyDatabaseConfig,com.example.MyJmsConfig
spring.main.banner-mode=console
spring:
main:
sources: "com.example.MyDatabaseConfig,com.example.MyJmsConfig"
banner-mode: "console"
The actual application will show the banner (as overridden by configuration) and uses three sources for the ApplicationContext
.
The application sources are:
-
MyApplication
(from the code) -
MyDatabaseConfig
(from the external config) -
MyJmsConfig
(from the external config)
18.2.3. Change the Location of External Properties of an Application
By default, properties from different sources are added to the Spring Environment
in a defined order (see “Externalized Configuration” in the ‘Spring Boot features’ section for the exact order).
You can also provide the following System properties (or environment variables) to change the behavior:
-
spring.config.name
(SPRING_CONFIG_NAME
): Defaults toapplication
as the root of the file name. -
spring.config.location
(SPRING_CONFIG_LOCATION
): The file to load (such as a classpath resource or a URL). A separateEnvironment
property source is set up for this document and it can be overridden by system properties, environment variables, or the command line.
No matter what you set in the environment, Spring Boot always loads application.properties
as described above.
By default, if YAML is used, then files with the ‘.yaml’ and ‘.yml’ extension are also added to the list.
If you want detailed information about the files that are being loaded you can set the logging level of org.springframework.boot.context.config to trace .
|
18.2.4. Use ‘Short’ Command Line Arguments
Some people like to use (for example) --port=9000
instead of --server.port=9000
to set configuration properties on the command line.
You can enable this behavior by using placeholders in application.properties
, as shown in the following example:
server.port=${port:8080}
server:
port: "${port:8080}"
If you inherit from the spring-boot-starter-parent POM, the default filter token of the maven-resources-plugins has been changed from ${*} to @ (that is, @maven.token@ instead of ${maven.token} ) to prevent conflicts with Spring-style placeholders.
If you have enabled Maven filtering for the application.properties directly, you may want to also change the default filter token to use other delimiters.
|
In this specific case, the port binding works in a PaaS environment such as Heroku or Cloud Foundry.
In those two platforms, the PORT environment variable is set automatically and Spring can bind to capitalized synonyms for Environment properties.
|
18.2.5. Use YAML for External Properties
YAML is a superset of JSON and, as such, is a convenient syntax for storing external properties in a hierarchical format, as shown in the following example:
spring:
application:
name: "cruncher"
datasource:
driver-class-name: "com.mysql.jdbc.Driver"
url: "jdbc:mysql://localhost/test"
server:
port: 9000
Create a file called application.yaml
and put it in the root of your classpath.
Then add snakeyaml
to your dependencies (Maven coordinates org.yaml:snakeyaml
, already included if you use the spring-boot-starter
).
A YAML file is parsed to a Java Map<String,Object>
(like a JSON object), and Spring Boot flattens the map so that it is one level deep and has period-separated keys, as many people are used to with Properties
files in Java.
The preceding example YAML corresponds to the following application.properties
file:
spring.application.name=cruncher
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost/test
server.port=9000
See “Working With YAML” in the ‘Spring Boot features’ section for more information about YAML.
18.2.6. Set the Active Spring Profiles
The Spring Environment
has an API for this, but you would normally set a System property (spring.profiles.active
) or an OS environment variable (SPRING_PROFILES_ACTIVE
).
Also, you can launch your application with a -D
argument (remember to put it before the main class or jar archive), as follows:
$ java -jar -Dspring.profiles.active=production demo-0.0.1-SNAPSHOT.jar
In Spring Boot, you can also set the active profile in application.properties
, as shown in the following example:
spring.profiles.active=production
spring:
profiles:
active: "production"
A value set this way is replaced by the System property or environment variable setting but not by the SpringApplicationBuilder.profiles()
method.
Thus, the latter Java API can be used to augment the profiles without changing the defaults.
See “Profiles” in the “Spring Boot features” section for more information.
18.2.7. Set the Default Profile Name
The default profile is a profile that is enabled if no profile is active.
By default, the name of the default profile is default
, but it could be changed using a System property (spring.profiles.default
) or an OS environment variable (SPRING_PROFILES_DEFAULT
).
In Spring Boot, you can also set the default profile name in application.properties
, as shown in the following example:
spring.profiles.default=dev
spring:
profiles:
default: "dev"
See “Profiles” in the “Spring Boot features” section for more information.
18.2.8. Change Configuration Depending on the Environment
Spring Boot supports multi-document YAML and Properties files (see Working With Multi-Document Files for details) which can be activated conditionally based on the active profiles.
If a document contains a spring.config.activate.on-profile
key, then the profiles value (a comma-separated list of profiles or a profile expression) is fed into the Spring Environment.acceptsProfiles()
method.
If the profile expression matches then that document is included in the final merge (otherwise, it is not), as shown in the following example:
server.port=9000
#---
spring.config.activate.on-profile=development
server.port=9001
#---
spring.config.activate.on-profile=production
server.port=0
server:
port: 9000
---
spring:
config:
activate:
on-profile: "development"
server:
port: 9001
---
spring:
config:
activate:
on-profile: "production"
server:
port: 0
In the preceding example, the default port is 9000. However, if the Spring profile called ‘development’ is active, then the port is 9001. If ‘production’ is active, then the port is 0.
The documents are merged in the order in which they are encountered. Later values override earlier values. |
18.2.9. Discover Built-in Options for External Properties
Spring Boot binds external properties from application.properties
(or YAML files and other places) into an application at runtime.
There is not (and technically cannot be) an exhaustive list of all supported properties in a single location, because contributions can come from additional jar files on your classpath.
A running application with the Actuator features has a configprops
endpoint that shows all the bound and bindable properties available through @ConfigurationProperties
.
The appendix includes an application.properties
example with a list of the most common properties supported by Spring Boot.
The definitive list comes from searching the source code for @ConfigurationProperties
and @Value
annotations as well as the occasional use of Binder
.
For more about the exact ordering of loading properties, see "Externalized Configuration".
18.3. Embedded Web Servers
Each Spring Boot web application includes an embedded web server. This feature leads to a number of how-to questions, including how to change the embedded server and how to configure the embedded server. This section answers those questions.
18.3.1. Use Another Web Server
Many Spring Boot starters include default embedded containers.
-
For servlet stack applications, the
spring-boot-starter-web
includes Tomcat by includingspring-boot-starter-tomcat
, but you can usespring-boot-starter-jetty
orspring-boot-starter-undertow
instead. -
For reactive stack applications, the
spring-boot-starter-webflux
includes Reactor Netty by includingspring-boot-starter-reactor-netty
, but you can usespring-boot-starter-tomcat
,spring-boot-starter-jetty
, orspring-boot-starter-undertow
instead.
When switching to a different HTTP server, you need to swap the default dependencies for those that you need instead. To help with this process, Spring Boot provides a separate starter for each of the supported HTTP servers.
The following Maven example shows how to exclude Tomcat and include Jetty for Spring MVC:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<!-- Exclude the Tomcat dependency -->
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<!-- Use Jetty instead -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jetty</artifactId>
</dependency>
The following Gradle example configures the necessary dependencies and a module replacement to use Undertow in place of Reactor Netty for Spring WebFlux:
dependencies {
implementation "org.springframework.boot:spring-boot-starter-undertow"
implementation "org.springframework.boot:spring-boot-starter-webflux"
modules {
module("org.springframework.boot:spring-boot-starter-reactor-netty") {
replacedBy("org.springframework.boot:spring-boot-starter-undertow", "Use Undertow instead of Reactor Netty")
}
}
}
spring-boot-starter-reactor-netty is required to use the WebClient class, so you may need to keep a dependency on Netty even when you need to include a different HTTP server.
|
18.3.2. Disabling the Web Server
If your classpath contains the necessary bits to start a web server, Spring Boot will automatically start it.
To disable this behavior configure the WebApplicationType
in your application.properties
, as shown in the following example:
spring.main.web-application-type=none
spring:
main:
web-application-type: "none"
18.3.3. Change the HTTP Port
In a standalone application, the main HTTP port defaults to 8080
but can be set with server.port
(for example, in application.properties
or as a System property).
Thanks to relaxed binding of Environment
values, you can also use SERVER_PORT
(for example, as an OS environment variable).
To switch off the HTTP endpoints completely but still create a WebApplicationContext
, use server.port=-1
(doing so is sometimes useful for testing).
For more details, see “Customizing Embedded Servlet Containers” in the ‘Spring Boot Features’ section, or the ServerProperties
source code.
18.3.4. Use a Random Unassigned HTTP Port
To scan for a free port (using OS natives to prevent clashes) use server.port=0
.
18.3.5. Discover the HTTP Port at Runtime
You can access the port the server is running on from log output or from the WebServerApplicationContext
through its WebServer
.
The best way to get that and be sure it has been initialized is to add a @Bean
of type ApplicationListener<WebServerInitializedEvent>
and pull the container out of the event when it is published.
Tests that use @SpringBootTest(webEnvironment=WebEnvironment.RANDOM_PORT)
can also inject the actual port into a field by using the @LocalServerPort
annotation, as shown in the following example:
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class MyWebIntegrationTests {
@LocalServerPort
int port;
// ...
}
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class MyWebIntegrationTests {
@LocalServerPort
var port = 0
// ...
}
|
18.3.6. Enable HTTP Response Compression
HTTP response compression is supported by Jetty, Tomcat, Reactor Netty, and Undertow.
It can be enabled in application.properties
, as follows:
server.compression.enabled=true
server:
compression:
enabled: true
By default, responses must be at least 2048 bytes in length for compression to be performed.
You can configure this behavior by setting the server.compression.min-response-size
property.
By default, responses are compressed only if their content type is one of the following:
-
text/html
-
text/xml
-
text/plain
-
text/css
-
text/javascript
-
application/javascript
-
application/json
-
application/xml
You can configure this behavior by setting the server.compression.mime-types
property.
18.3.7. Configure SSL
SSL can be configured declaratively by setting the various server.ssl.*
properties, typically in application.properties
or application.yaml
.
The following example shows setting SSL properties using a Java KeyStore file:
server.port=8443
server.ssl.key-store=classpath:keystore.jks
server.ssl.key-store-password=secret
server.ssl.key-password=another-secret
server:
port: 8443
ssl:
key-store: "classpath:keystore.jks"
key-store-password: "secret"
key-password: "another-secret"
Using configuration such as the preceding example means the application no longer supports a plain HTTP connector at port 8080.
Spring Boot does not support the configuration of both an HTTP connector and an HTTPS connector through application.properties
.
If you want to have both, you need to configure one of them programmatically.
We recommend using application.properties
to configure HTTPS, as the HTTP connector is the easier of the two to configure programmatically.
Using PEM-encoded files
You can use PEM-encoded files instead of Java KeyStore files.
You should use PKCS#8 key files wherever possible.
PEM-encoded PKCS#8 key files start with a -----BEGIN PRIVATE KEY-----
or -----BEGIN ENCRYPTED PRIVATE KEY-----
header.
If you have files in other formats, e.g., PKCS#1 (-----BEGIN RSA PRIVATE KEY-----
) or SEC 1 (-----BEGIN EC PRIVATE KEY-----
), you can convert them to PKCS#8 using OpenSSL:
openssl pkcs8 -topk8 -nocrypt -in <input file> -out <output file>
The following example shows setting SSL properties using PEM-encoded certificate and private key files:
server.port=8443
server.ssl.certificate=classpath:my-cert.crt
server.ssl.certificate-private-key=classpath:my-cert.key
server.ssl.trust-certificate=classpath:ca-cert.crt
server:
port: 8443
ssl:
certificate: "classpath:my-cert.crt"
certificate-private-key: "classpath:my-cert.key"
trust-certificate: "classpath:ca-cert.crt"
Alternatively, the SSL trust material can be configured in an SSL bundle and applied to the web server as shown in this example:
server.port=8443
server.ssl.bundle=example
server:
port: 8443
ssl:
bundle: "example"
See Ssl
for details of all of the supported properties.
18.3.8. Configure HTTP/2
You can enable HTTP/2 support in your Spring Boot application with the server.http2.enabled
configuration property.
Both h2
(HTTP/2 over TLS) and h2c
(HTTP/2 over TCP) are supported.
To use h2
, SSL must also be enabled.
When SSL is not enabled, h2c
will be used.
You may, for example, want to use h2c
when your application is running behind a proxy server that is performing TLS termination.
HTTP/2 With Tomcat
Spring Boot ships by default with Tomcat 10.1.x which supports h2c
and h2
out of the box.
Alternatively, you can use libtcnative
for h2
support if the library and its dependencies are installed on the host operating system.
The library directory must be made available, if not already, to the JVM library path.
You can do so with a JVM argument such as -Djava.library.path=/usr/local/opt/tomcat-native/lib
.
More on this in the official Tomcat documentation.
HTTP/2 With Jetty
For HTTP/2 support, Jetty requires the additional org.eclipse.jetty.http2:http2-server
dependency.
To use h2c
no other dependencies are required.
To use h2
, you also need to choose one of the following dependencies, depending on your deployment:
-
org.eclipse.jetty:jetty-alpn-java-server
to use the JDK built-in support -
org.eclipse.jetty:jetty-alpn-conscrypt-server
and the Conscrypt library
HTTP/2 With Reactor Netty
The spring-boot-webflux-starter
is using by default Reactor Netty as a server.
Reactor Netty supports h2c
and h2
out of the box.
For optimal runtime performance, this server also supports h2
with native libraries.
To enable that, your application needs to have an additional dependency.
Spring Boot manages the version for the io.netty:netty-tcnative-boringssl-static
"uber jar", containing native libraries for all platforms.
Developers can choose to import only the required dependencies using a classifier (see the Netty official documentation).
18.3.9. Configure the Web Server
Generally, you should first consider using one of the many available configuration keys and customize your web server by adding new entries in your application.properties
or application.yaml
file.
See “Discover Built-in Options for External Properties”).
The server.*
namespace is quite useful here, and it includes namespaces like server.tomcat.*
, server.jetty.*
and others, for server-specific features.
See the list of Common Application Properties.
The previous sections covered already many common use cases, such as compression, SSL or HTTP/2.
However, if a configuration key does not exist for your use case, you should then look at WebServerFactoryCustomizer
.
You can declare such a component and get access to the server factory relevant to your choice: you should select the variant for the chosen Server (Tomcat, Jetty, Reactor Netty, Undertow) and the chosen web stack (servlet or reactive).
The example below is for Tomcat with the spring-boot-starter-web
(servlet stack):
@Component
public class MyTomcatWebServerCustomizer implements WebServerFactoryCustomizer<TomcatServletWebServerFactory> {
@Override
public void customize(TomcatServletWebServerFactory factory) {
// customize the factory here
}
}
@Component
class MyTomcatWebServerCustomizer : WebServerFactoryCustomizer<TomcatServletWebServerFactory?> {
override fun customize(factory: TomcatServletWebServerFactory?) {
// customize the factory here
}
}
Spring Boot uses that infrastructure internally to auto-configure the server.
Auto-configured WebServerFactoryCustomizer beans have an order of 0 and will be processed before any user-defined customizers, unless it has an explicit order that states otherwise.
|
Once you have got access to a WebServerFactory
using the customizer, you can use it to configure specific parts, like connectors, server resources, or the server itself - all using server-specific APIs.
In addition Spring Boot provides:
Server | Servlet stack | Reactive stack |
---|---|---|
Tomcat |
|
|
Jetty |
|
|
Undertow |
|
|
Reactor |
N/A |
|
As a last resort, you can also declare your own WebServerFactory
bean, which will override the one provided by Spring Boot.
When you do so, auto-configured customizers are still applied on your custom factory, so use that option carefully.
18.3.10. Add a Servlet, Filter, or Listener to an Application
In a servlet stack application, that is with the spring-boot-starter-web
, there are two ways to add Servlet
, Filter
, ServletContextListener
, and the other listeners supported by the Servlet API to your application:
Add a Servlet, Filter, or Listener by Using a Spring Bean
To add a Servlet
, Filter
, or servlet *Listener
by using a Spring bean, you must provide a @Bean
definition for it.
Doing so can be very useful when you want to inject configuration or dependencies.
However, you must be very careful that they do not cause eager initialization of too many other beans, because they have to be installed in the container very early in the application lifecycle.
(For example, it is not a good idea to have them depend on your DataSource
or JPA configuration.)
You can work around such restrictions by initializing the beans lazily when first used instead of on initialization.
In the case of filters and servlets, you can also add mappings and init parameters by adding a FilterRegistrationBean
or a ServletRegistrationBean
instead of or in addition to the underlying component.
If no |
Like any other Spring bean, you can define the order of servlet filter beans; please make sure to check the “Registering Servlets, Filters, and Listeners as Spring Beans” section.
Disable Registration of a Servlet or Filter
As described earlier, any Servlet
or Filter
beans are registered with the servlet container automatically.
To disable registration of a particular Filter
or Servlet
bean, create a registration bean for it and mark it as disabled, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyFilterConfiguration {
@Bean
public FilterRegistrationBean<MyFilter> registration(MyFilter filter) {
FilterRegistrationBean<MyFilter> registration = new FilterRegistrationBean<>(filter);
registration.setEnabled(false);
return registration;
}
}
@Configuration(proxyBeanMethods = false)
class MyFilterConfiguration {
@Bean
fun registration(filter: MyFilter): FilterRegistrationBean<MyFilter> {
val registration = FilterRegistrationBean(filter)
registration.isEnabled = false
return registration
}
}
Add Servlets, Filters, and Listeners by Using Classpath Scanning
@WebServlet
, @WebFilter
, and @WebListener
annotated classes can be automatically registered with an embedded servlet container by annotating a @Configuration
class with @ServletComponentScan
and specifying the package(s) containing the components that you want to register.
By default, @ServletComponentScan
scans from the package of the annotated class.
18.3.11. Configure Access Logging
Access logs can be configured for Tomcat, Undertow, and Jetty through their respective namespaces.
For instance, the following settings log access on Tomcat with a custom pattern.
server.tomcat.basedir=my-tomcat
server.tomcat.accesslog.enabled=true
server.tomcat.accesslog.pattern=%t %a %r %s (%D microseconds)
server:
tomcat:
basedir: "my-tomcat"
accesslog:
enabled: true
pattern: "%t %a %r %s (%D microseconds)"
The default location for logs is a logs directory relative to the Tomcat base directory.
By default, the logs directory is a temporary directory, so you may want to fix Tomcat’s base directory or use an absolute path for the logs.
In the preceding example, the logs are available in my-tomcat/logs relative to the working directory of the application.
|
Access logging for Undertow can be configured in a similar fashion, as shown in the following example:
server.undertow.accesslog.enabled=true
server.undertow.accesslog.pattern=%t %a %r %s (%D milliseconds)
server.undertow.options.server.record-request-start-time=true
server:
undertow:
accesslog:
enabled: true
pattern: "%t %a %r %s (%D milliseconds)"
options:
server:
record-request-start-time: true
Note that, in addition to enabling access logging and configuring its pattern, recording request start times has also been enabled.
This is required when including the response time (%D
) in the access log pattern.
Logs are stored in a logs
directory relative to the working directory of the application.
You can customize this location by setting the server.undertow.accesslog.dir
property.
Finally, access logging for Jetty can also be configured as follows:
server.jetty.accesslog.enabled=true
server.jetty.accesslog.filename=/var/log/jetty-access.log
server:
jetty:
accesslog:
enabled: true
filename: "/var/log/jetty-access.log"
By default, logs are redirected to System.err
.
For more details, see the Jetty documentation.
18.3.12. Running Behind a Front-end Proxy Server
If your application is running behind a proxy, a load-balancer or in the cloud, the request information (like the host, port, scheme…) might change along the way.
Your application may be running on 10.10.10.10:8080
, but HTTP clients should only see example.org
.
RFC7239 "Forwarded Headers" defines the Forwarded
HTTP header; proxies can use this header to provide information about the original request.
You can configure your application to read those headers and automatically use that information when creating links and sending them to clients in HTTP 302 responses, JSON documents or HTML pages.
There are also non-standard headers, like X-Forwarded-Host
, X-Forwarded-Port
, X-Forwarded-Proto
, X-Forwarded-Ssl
, and X-Forwarded-Prefix
.
If the proxy adds the commonly used X-Forwarded-For
and X-Forwarded-Proto
headers, setting server.forward-headers-strategy
to NATIVE
is enough to support those.
With this option, the Web servers themselves natively support this feature; you can check their specific documentation to learn about specific behavior.
If this is not enough, Spring Framework provides a ForwardedHeaderFilter for the servlet stack and a ForwardedHeaderTransformer for the reactive stack.
You can use them in your application by setting server.forward-headers-strategy
to FRAMEWORK
.
If you are using Tomcat and terminating SSL at the proxy, server.tomcat.redirect-context-root should be set to false .
This allows the X-Forwarded-Proto header to be honored before any redirects are performed.
|
If your application runs in Cloud Foundry, Heroku or Kubernetes, the server.forward-headers-strategy property defaults to NATIVE .
In all other instances, it defaults to NONE .
|
Customize Tomcat’s Proxy Configuration
If you use Tomcat, you can additionally configure the names of the headers used to carry “forwarded” information, as shown in the following example:
server.tomcat.remoteip.remote-ip-header=x-your-remote-ip-header
server.tomcat.remoteip.protocol-header=x-your-protocol-header
server:
tomcat:
remoteip:
remote-ip-header: "x-your-remote-ip-header"
protocol-header: "x-your-protocol-header"
Tomcat is also configured with a regular expression that matches internal proxies that are to be trusted.
See the server.tomcat.remoteip.internal-proxies
entry in the appendix for its default value.
You can customize the valve’s configuration by adding an entry to application.properties
, as shown in the following example:
server.tomcat.remoteip.internal-proxies=192\\.168\\.\\d{1,3}\\.\\d{1,3}
server:
tomcat:
remoteip:
internal-proxies: "192\\.168\\.\\d{1,3}\\.\\d{1,3}"
You can trust all proxies by setting the internal-proxies to empty (but do not do so in production).
|
You can take complete control of the configuration of Tomcat’s RemoteIpValve
by switching the automatic one off (to do so, set server.forward-headers-strategy=NONE
) and adding a new valve instance using a WebServerFactoryCustomizer
bean.
18.3.13. Enable Multiple Connectors with Tomcat
You can add an org.apache.catalina.connector.Connector
to the TomcatServletWebServerFactory
, which can allow multiple connectors, including HTTP and HTTPS connectors, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyTomcatConfiguration {
@Bean
public WebServerFactoryCustomizer<TomcatServletWebServerFactory> connectorCustomizer() {
return (tomcat) -> tomcat.addAdditionalTomcatConnectors(createConnector());
}
private Connector createConnector() {
Connector connector = new Connector("org.apache.coyote.http11.Http11NioProtocol");
connector.setPort(8081);
return connector;
}
}
@Configuration(proxyBeanMethods = false)
class MyTomcatConfiguration {
@Bean
fun connectorCustomizer(): WebServerFactoryCustomizer<TomcatServletWebServerFactory> {
return WebServerFactoryCustomizer { tomcat: TomcatServletWebServerFactory ->
tomcat.addAdditionalTomcatConnectors(
createConnector()
)
}
}
private fun createConnector(): Connector {
val connector = Connector("org.apache.coyote.http11.Http11NioProtocol")
connector.port = 8081
return connector
}
}
18.3.14. Enable Tomcat’s MBean Registry
Embedded Tomcat’s MBean registry is disabled by default.
This minimizes Tomcat’s memory footprint.
If you want to use Tomcat’s MBeans, for example so that they can be used by Micrometer to expose metrics, you must use the server.tomcat.mbeanregistry.enabled
property to do so, as shown in the following example:
server.tomcat.mbeanregistry.enabled=true
server:
tomcat:
mbeanregistry:
enabled: true
18.3.15. Enable Multiple Listeners with Undertow
Add an UndertowBuilderCustomizer
to the UndertowServletWebServerFactory
and add a listener to the Builder
, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyUndertowConfiguration {
@Bean
public WebServerFactoryCustomizer<UndertowServletWebServerFactory> undertowListenerCustomizer() {
return (factory) -> factory.addBuilderCustomizers(this::addHttpListener);
}
private Builder addHttpListener(Builder builder) {
return builder.addHttpListener(8080, "0.0.0.0");
}
}
@Configuration(proxyBeanMethods = false)
class MyUndertowConfiguration {
@Bean
fun undertowListenerCustomizer(): WebServerFactoryCustomizer<UndertowServletWebServerFactory> {
return WebServerFactoryCustomizer { factory: UndertowServletWebServerFactory ->
factory.addBuilderCustomizers(
UndertowBuilderCustomizer { builder: Undertow.Builder -> addHttpListener(builder) })
}
}
private fun addHttpListener(builder: Undertow.Builder): Undertow.Builder {
return builder.addHttpListener(8080, "0.0.0.0")
}
}
18.3.16. Create WebSocket Endpoints Using @ServerEndpoint
If you want to use @ServerEndpoint
in a Spring Boot application that used an embedded container, you must declare a single ServerEndpointExporter
@Bean
, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyWebSocketConfiguration {
@Bean
public ServerEndpointExporter serverEndpointExporter() {
return new ServerEndpointExporter();
}
}
@Configuration(proxyBeanMethods = false)
class MyWebSocketConfiguration {
@Bean
fun serverEndpointExporter(): ServerEndpointExporter {
return ServerEndpointExporter()
}
}
The bean shown in the preceding example registers any @ServerEndpoint
annotated beans with the underlying WebSocket container.
When deployed to a standalone servlet container, this role is performed by a servlet container initializer, and the ServerEndpointExporter
bean is not required.
18.4. Spring MVC
Spring Boot has a number of starters that include Spring MVC. Note that some starters include a dependency on Spring MVC rather than include it directly. This section answers common questions about Spring MVC and Spring Boot.
18.4.1. Write a JSON REST Service
Any Spring @RestController
in a Spring Boot application should render JSON response by default as long as Jackson2 is on the classpath, as shown in the following example:
@RestController
public class MyController {
@RequestMapping("/thing")
public MyThing thing() {
return new MyThing();
}
}
@RestController
class MyController {
@RequestMapping("/thing")
fun thing(): MyThing {
return MyThing()
}
}
As long as MyThing
can be serialized by Jackson2 (true for a normal POJO or Groovy object), then localhost:8080/thing
serves a JSON representation of it by default.
Note that, in a browser, you might sometimes see XML responses, because browsers tend to send accept headers that prefer XML.
18.4.2. Write an XML REST Service
If you have the Jackson XML extension (jackson-dataformat-xml
) on the classpath, you can use it to render XML responses.
The previous example that we used for JSON would work.
To use the Jackson XML renderer, add the following dependency to your project:
<dependency>
<groupId>com.fasterxml.jackson.dataformat</groupId>
<artifactId>jackson-dataformat-xml</artifactId>
</dependency>
If Jackson’s XML extension is not available and JAXB is available, XML can be rendered with the additional requirement of having MyThing
annotated as @XmlRootElement
, as shown in the following example:
@XmlRootElement
public class MyThing {
private String name;
}
@XmlRootElement
class MyThing {
var name: String? = null
}
You will need to ensure that the JAXB library is part of your project, for example by adding:
<dependency>
<groupId>org.glassfish.jaxb</groupId>
<artifactId>jaxb-runtime</artifactId>
</dependency>
To get the server to render XML instead of JSON, you might have to send an Accept: text/xml header (or use a browser).
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18.4.3. Customize the Jackson ObjectMapper
Spring MVC (client and server side) uses HttpMessageConverters
to negotiate content conversion in an HTTP exchange.
If Jackson is on the classpath, you already get the default converter(s) provided by Jackson2ObjectMapperBuilder
, an instance of which is auto-configured for you.
The ObjectMapper
(or XmlMapper
for Jackson XML converter) instance (created by default) has the following customized properties:
-
MapperFeature.DEFAULT_VIEW_INCLUSION
is disabled -
DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES
is disabled -
SerializationFeature.WRITE_DATES_AS_TIMESTAMPS
is disabled -
SerializationFeature.WRITE_DURATIONS_AS_TIMESTAMPS
is disabled
Spring Boot also has some features to make it easier to customize this behavior.
You can configure the ObjectMapper
and XmlMapper
instances by using the environment.
Jackson provides an extensive suite of on/off features that can be used to configure various aspects of its processing.
These features are described in several enums (in Jackson) that map onto properties in the environment:
Enum | Property | Values |
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For example, to enable pretty print, set spring.jackson.serialization.indent_output=true
.
Note that, thanks to the use of relaxed binding, the case of indent_output
does not have to match the case of the corresponding enum constant, which is INDENT_OUTPUT
.
This environment-based configuration is applied to the auto-configured Jackson2ObjectMapperBuilder
bean and applies to any mappers created by using the builder, including the auto-configured ObjectMapper
bean.
The context’s Jackson2ObjectMapperBuilder
can be customized by one or more Jackson2ObjectMapperBuilderCustomizer
beans.
Such customizer beans can be ordered (Boot’s own customizer has an order of 0), letting additional customization be applied both before and after Boot’s customization.
Any beans of type com.fasterxml.jackson.databind.Module
are automatically registered with the auto-configured Jackson2ObjectMapperBuilder
and are applied to any ObjectMapper
instances that it creates.
This provides a global mechanism for contributing custom modules when you add new features to your application.
If you want to replace the default ObjectMapper
completely, either define a @Bean
of that type and mark it as @Primary
or, if you prefer the builder-based approach, define a Jackson2ObjectMapperBuilder
@Bean
.
Note that, in either case, doing so disables all auto-configuration of the ObjectMapper
.
If you provide any @Beans
of type MappingJackson2HttpMessageConverter
, they replace the default value in the MVC configuration.
Also, a convenience bean of type HttpMessageConverters
is provided (and is always available if you use the default MVC configuration).
It has some useful methods to access the default and user-enhanced message converters.
See the “Customize the @ResponseBody Rendering” section and the WebMvcAutoConfiguration
source code for more details.
18.4.4. Customize the @ResponseBody Rendering
Spring uses HttpMessageConverters
to render @ResponseBody
(or responses from @RestController
).
You can contribute additional converters by adding beans of the appropriate type in a Spring Boot context.
If a bean you add is of a type that would have been included by default anyway (such as MappingJackson2HttpMessageConverter
for JSON conversions), it replaces the default value.
A convenience bean of type HttpMessageConverters
is provided and is always available if you use the default MVC configuration.
It has some useful methods to access the default and user-enhanced message converters (For example, it can be useful if you want to manually inject them into a custom RestTemplate
).
As in normal MVC usage, any WebMvcConfigurer
beans that you provide can also contribute converters by overriding the configureMessageConverters
method.
However, unlike with normal MVC, you can supply only additional converters that you need (because Spring Boot uses the same mechanism to contribute its defaults).
Finally, if you opt out of the Spring Boot default MVC configuration by providing your own @EnableWebMvc
configuration, you can take control completely and do everything manually by using getMessageConverters
from WebMvcConfigurationSupport
.
See the WebMvcAutoConfiguration
source code for more details.
18.4.5. Handling Multipart File Uploads
Spring Boot embraces the servlet 5 jakarta.servlet.http.Part
API to support uploading files.
By default, Spring Boot configures Spring MVC with a maximum size of 1MB per file and a maximum of 10MB of file data in a single request.
You may override these values, the location to which intermediate data is stored (for example, to the /tmp
directory), and the threshold past which data is flushed to disk by using the properties exposed in the MultipartProperties
class.
For example, if you want to specify that files be unlimited, set the spring.servlet.multipart.max-file-size
property to -1
.
The multipart support is helpful when you want to receive multipart encoded file data as a @RequestParam
-annotated parameter of type MultipartFile
in a Spring MVC controller handler method.
See the MultipartAutoConfiguration
source for more details.
It is recommended to use the container’s built-in support for multipart uploads rather than introducing an additional dependency such as Apache Commons File Upload. |
18.4.6. Switch Off the Spring MVC DispatcherServlet
By default, all content is served from the root of your application (/
).
If you would rather map to a different path, you can configure one as follows:
spring.mvc.servlet.path=/mypath
spring:
mvc:
servlet:
path: "/mypath"
If you have additional servlets you can declare a @Bean
of type Servlet
or ServletRegistrationBean
for each and Spring Boot will register them transparently to the container.
Because servlets are registered that way, they can be mapped to a sub-context of the DispatcherServlet
without invoking it.
Configuring the DispatcherServlet
yourself is unusual but if you really need to do it, a @Bean
of type DispatcherServletPath
must be provided as well to provide the path of your custom DispatcherServlet
.
18.4.7. Switch off the Default MVC Configuration
The easiest way to take complete control over MVC configuration is to provide your own @Configuration
with the @EnableWebMvc
annotation.
Doing so leaves all MVC configuration in your hands.
18.4.8. Customize ViewResolvers
A ViewResolver
is a core component of Spring MVC, translating view names in @Controller
to actual View
implementations.
Note that ViewResolvers
are mainly used in UI applications, rather than REST-style services (a View
is not used to render a @ResponseBody
).
There are many implementations of ViewResolver
to choose from, and Spring on its own is not opinionated about which ones you should use.
Spring Boot, on the other hand, installs one or two for you, depending on what it finds on the classpath and in the application context.
The DispatcherServlet
uses all the resolvers it finds in the application context, trying each one in turn until it gets a result.
If you add your own, you have to be aware of the order and in which position your resolver is added.
WebMvcAutoConfiguration
adds the following ViewResolvers
to your context:
-
An
InternalResourceViewResolver
named ‘defaultViewResolver’. This one locates physical resources that can be rendered by using theDefaultServlet
(including static resources and JSP pages, if you use those). It applies a prefix and a suffix to the view name and then looks for a physical resource with that path in the servlet context (the defaults are both empty but are accessible for external configuration throughspring.mvc.view.prefix
andspring.mvc.view.suffix
). You can override it by providing a bean of the same type. -
A
BeanNameViewResolver
named ‘beanNameViewResolver’. This is a useful member of the view resolver chain and picks up any beans with the same name as theView
being resolved. It should not be necessary to override or replace it. -
A
ContentNegotiatingViewResolver
named ‘viewResolver’ is added only if there are actually beans of typeView
present. This is a composite resolver, delegating to all the others and attempting to find a match to the ‘Accept’ HTTP header sent by the client. There is a useful blog aboutContentNegotiatingViewResolver
that you might like to study to learn more, and you might also look at the source code for detail. You can switch off the auto-configuredContentNegotiatingViewResolver
by defining a bean named ‘viewResolver’. -
If you use Thymeleaf, you also have a
ThymeleafViewResolver
named ‘thymeleafViewResolver’. It looks for resources by surrounding the view name with a prefix and suffix. The prefix isspring.thymeleaf.prefix
, and the suffix isspring.thymeleaf.suffix
. The values of the prefix and suffix default to ‘classpath:/templates/’ and ‘.html’, respectively. You can overrideThymeleafViewResolver
by providing a bean of the same name. -
If you use FreeMarker, you also have a
FreeMarkerViewResolver
named ‘freeMarkerViewResolver’. It looks for resources in a loader path (which is externalized tospring.freemarker.templateLoaderPath
and has a default value of ‘classpath:/templates/’) by surrounding the view name with a prefix and a suffix. The prefix is externalized tospring.freemarker.prefix
, and the suffix is externalized tospring.freemarker.suffix
. The default values of the prefix and suffix are empty and ‘.ftlh’, respectively. You can overrideFreeMarkerViewResolver
by providing a bean of the same name. -
If you use Groovy templates (actually, if
groovy-templates
is on your classpath), you also have aGroovyMarkupViewResolver
named ‘groovyMarkupViewResolver’. It looks for resources in a loader path by surrounding the view name with a prefix and suffix (externalized tospring.groovy.template.prefix
andspring.groovy.template.suffix
). The prefix and suffix have default values of ‘classpath:/templates/’ and ‘.tpl’, respectively. You can overrideGroovyMarkupViewResolver
by providing a bean of the same name. -
If you use Mustache, you also have a
MustacheViewResolver
named ‘mustacheViewResolver’. It looks for resources by surrounding the view name with a prefix and suffix. The prefix isspring.mustache.prefix
, and the suffix isspring.mustache.suffix
. The values of the prefix and suffix default to ‘classpath:/templates/’ and ‘.mustache’, respectively. You can overrideMustacheViewResolver
by providing a bean of the same name.
For more detail, see the following sections:
18.5. Jersey
18.5.1. Secure Jersey endpoints with Spring Security
Spring Security can be used to secure a Jersey-based web application in much the same way as it can be used to secure a Spring MVC-based web application.
However, if you want to use Spring Security’s method-level security with Jersey, you must configure Jersey to use setStatus(int)
rather sendError(int)
.
This prevents Jersey from committing the response before Spring Security has had an opportunity to report an authentication or authorization failure to the client.
The jersey.config.server.response.setStatusOverSendError
property must be set to true
on the application’s ResourceConfig
bean, as shown in the following example:
@Component
public class JerseySetStatusOverSendErrorConfig extends ResourceConfig {
public JerseySetStatusOverSendErrorConfig() {
register(Endpoint.class);
setProperties(Collections.singletonMap("jersey.config.server.response.setStatusOverSendError", true));
}
}
18.5.2. Use Jersey Alongside Another Web Framework
To use Jersey alongside another web framework, such as Spring MVC, it should be configured so that it will allow the other framework to handle requests that it cannot handle.
First, configure Jersey to use a filter rather than a servlet by configuring the spring.jersey.type
application property with a value of filter
.
Second, configure your ResourceConfig
to forward requests that would have resulted in a 404, as shown in the following example.
@Component
public class JerseyConfig extends ResourceConfig {
public JerseyConfig() {
register(Endpoint.class);
property(ServletProperties.FILTER_FORWARD_ON_404, true);
}
}
18.6. HTTP Clients
Spring Boot offers a number of starters that work with HTTP clients. This section answers questions related to using them.
18.6.1. Configure RestTemplate to Use a Proxy
As described in RestTemplate Customization, you can use a RestTemplateCustomizer
with RestTemplateBuilder
to build a customized RestTemplate
.
This is the recommended approach for creating a RestTemplate
configured to use a proxy.
The exact details of the proxy configuration depend on the underlying client request factory that is being used.
18.6.2. Configure the TcpClient used by a Reactor Netty-based WebClient
When Reactor Netty is on the classpath a Reactor Netty-based WebClient
is auto-configured.
To customize the client’s handling of network connections, provide a ClientHttpConnector
bean.
The following example configures a 60 second connect timeout and adds a ReadTimeoutHandler
:
@Configuration(proxyBeanMethods = false)
public class MyReactorNettyClientConfiguration {
@Bean
ClientHttpConnector clientHttpConnector(ReactorResourceFactory resourceFactory) {
HttpClient httpClient = HttpClient.create(resourceFactory.getConnectionProvider())
.runOn(resourceFactory.getLoopResources())
.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 60000)
.doOnConnected((connection) -> connection.addHandlerLast(new ReadTimeoutHandler(60)));
return new ReactorClientHttpConnector(httpClient);
}
}
@Configuration(proxyBeanMethods = false)
class MyReactorNettyClientConfiguration {
@Bean
fun clientHttpConnector(resourceFactory: ReactorResourceFactory): ClientHttpConnector {
val httpClient = HttpClient.create(resourceFactory.connectionProvider)
.runOn(resourceFactory.loopResources)
.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 60000)
.doOnConnected { connection ->
connection.addHandlerLast(ReadTimeoutHandler(60))
}
return ReactorClientHttpConnector(httpClient)
}
}
Note the use of ReactorResourceFactory for the connection provider and event loop resources.
This ensures efficient sharing of resources for the server receiving requests and the client making requests.
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18.7. Logging
Spring Boot has no mandatory logging dependency, except for the Commons Logging API, which is typically provided by Spring Framework’s spring-jcl
module.
To use Logback, you need to include it and spring-jcl
on the classpath.
The recommended way to do that is through the starters, which all depend on spring-boot-starter-logging
.
For a web application, you need only spring-boot-starter-web
, since it depends transitively on the logging starter.
If you use Maven, the following dependency adds logging for you:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
Spring Boot has a LoggingSystem
abstraction that attempts to configure logging based on the content of the classpath.
If Logback is available, it is the first choice.
If the only change you need to make to logging is to set the levels of various loggers, you can do so in application.properties
by using the "logging.level" prefix, as shown in the following example:
logging.level.org.springframework.web=debug
logging.level.org.hibernate=error
logging:
level:
org.springframework.web: "debug"
org.hibernate: "error"
You can also set the location of a file to which to write the log (in addition to the console) by using logging.file.name
.
To configure the more fine-grained settings of a logging system, you need to use the native configuration format supported by the LoggingSystem
in question.
By default, Spring Boot picks up the native configuration from its default location for the system (such as classpath:logback.xml
for Logback), but you can set the location of the config file by using the logging.config
property.
18.7.1. Configure Logback for Logging
If you need to apply customizations to logback beyond those that can be achieved with application.properties
, you will need to add a standard logback configuration file.
You can add a logback.xml
file to the root of your classpath for logback to find.
You can also use logback-spring.xml
if you want to use the Spring Boot Logback extensions.
The Logback documentation has a dedicated section that covers configuration in some detail. |
Spring Boot provides a number of logback configurations that can be included
in your own configuration.
These includes are designed to allow certain common Spring Boot conventions to be re-applied.
The following files are provided under org/springframework/boot/logging/logback/
:
-
defaults.xml
- Provides conversion rules, pattern properties and common logger configurations. -
console-appender.xml
- Adds aConsoleAppender
using theCONSOLE_LOG_PATTERN
. -
file-appender.xml
- Adds aRollingFileAppender
using theFILE_LOG_PATTERN
andROLLING_FILE_NAME_PATTERN
with appropriate settings.
In addition, a legacy base.xml
file is provided for compatibility with earlier versions of Spring Boot.
A typical custom logback.xml
file would look something like this:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<include resource="org/springframework/boot/logging/logback/defaults.xml"/>
<include resource="org/springframework/boot/logging/logback/console-appender.xml" />
<root level="INFO">
<appender-ref ref="CONSOLE" />
</root>
<logger name="org.springframework.web" level="DEBUG"/>
</configuration>
Your logback configuration file can also make use of System properties that the LoggingSystem
takes care of creating for you:
-
${PID}
: The current process ID. -
${LOG_FILE}
: Whetherlogging.file.name
was set in Boot’s external configuration. -
${LOG_PATH}
: Whetherlogging.file.path
(representing a directory for log files to live in) was set in Boot’s external configuration. -
${LOG_EXCEPTION_CONVERSION_WORD}
: Whetherlogging.exception-conversion-word
was set in Boot’s external configuration. -
${ROLLING_FILE_NAME_PATTERN}
: Whetherlogging.pattern.rolling-file-name
was set in Boot’s external configuration.
Spring Boot also provides some nice ANSI color terminal output on a console (but not in a log file) by using a custom Logback converter.
See the CONSOLE_LOG_PATTERN
in the defaults.xml
configuration for an example.
If Groovy is on the classpath, you should be able to configure Logback with logback.groovy
as well.
If present, this setting is given preference.
Spring extensions are not supported with Groovy configuration.
Any logback-spring.groovy files will not be detected.
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Configure Logback for File-only Output
If you want to disable console logging and write output only to a file, you need a custom logback-spring.xml
that imports file-appender.xml
but not console-appender.xml
, as shown in the following example:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<include resource="org/springframework/boot/logging/logback/defaults.xml" />
<property name="LOG_FILE" value="${LOG_FILE:-${LOG_PATH:-${LOG_TEMP:-${java.io.tmpdir:-/tmp}}/}spring.log}"/>
<include resource="org/springframework/boot/logging/logback/file-appender.xml" />
<root level="INFO">
<appender-ref ref="FILE" />
</root>
</configuration>
You also need to add logging.file.name
to your application.properties
or application.yaml
, as shown in the following example:
logging.file.name=myapplication.log
logging:
file:
name: "myapplication.log"
18.7.2. Configure Log4j for Logging
Spring Boot supports Log4j 2 for logging configuration if it is on the classpath.
If you use the starters for assembling dependencies, you have to exclude Logback and then include Log4j 2 instead.
If you do not use the starters, you need to provide (at least) spring-jcl
in addition to Log4j 2.
The recommended path is through the starters, even though it requires some jiggling. The following example shows how to set up the starters in Maven:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>
Gradle provides a few different ways to set up the starters. One way is to use a module replacement. To do so, declare a dependency on the Log4j 2 starter and tell Gradle that any occurrences of the default logging starter should be replaced by the Log4j 2 starter, as shown in the following example:
dependencies {
implementation "org.springframework.boot:spring-boot-starter-log4j2"
modules {
module("org.springframework.boot:spring-boot-starter-logging") {
replacedBy("org.springframework.boot:spring-boot-starter-log4j2", "Use Log4j2 instead of Logback")
}
}
}
The Log4j starters gather together the dependencies for common logging requirements (such as having Tomcat use java.util.logging but configuring the output using Log4j 2).
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To ensure that debug logging performed using java.util.logging is routed into Log4j 2, configure its JDK logging adapter by setting the java.util.logging.manager system property to org.apache.logging.log4j.jul.LogManager .
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Use YAML or JSON to Configure Log4j 2
In addition to its default XML configuration format, Log4j 2 also supports YAML and JSON configuration files. To configure Log4j 2 to use an alternative configuration file format, add the appropriate dependencies to the classpath and name your configuration files to match your chosen file format, as shown in the following example:
Format | Dependencies | File names |
---|---|---|
YAML |
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JSON |
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Use Composite Configuration to Configure Log4j 2
Log4j 2 has support for combining multiple configuration files into a single composite configuration.
To use this support in Spring Boot, configure logging.log4j2.config.override
with the locations of one or more secondary configuration files.
The secondary configuration files will be merged with the primary configuration, whether the primary’s source is Spring Boot’s defaults, a standard location such as log4j.xml
, or the location configured by the logging.config
property.
18.8. Data Access
Spring Boot includes a number of starters for working with data sources. This section answers questions related to doing so.
18.8.1. Configure a Custom DataSource
To configure your own DataSource
, define a @Bean
of that type in your configuration.
Spring Boot reuses your DataSource
anywhere one is required, including database initialization.
If you need to externalize some settings, you can bind your DataSource
to the environment (see “Third-party Configuration”).
The following example shows how to define a data source in a bean:
@Configuration(proxyBeanMethods = false)
public class MyDataSourceConfiguration {
@Bean
@ConfigurationProperties(prefix = "app.datasource")
public SomeDataSource dataSource() {
return new SomeDataSource();
}
}
@Configuration(proxyBeanMethods = false)
class MyDataSourceConfiguration {
@Bean
@ConfigurationProperties(prefix = "app.datasource")
fun dataSource(): SomeDataSource {
return SomeDataSource()
}
}
The following example shows how to define a data source by setting properties:
app.datasource.url=jdbc:h2:mem:mydb
app.datasource.username=sa
app.datasource.pool-size=30
app:
datasource:
url: "jdbc:h2:mem:mydb"
username: "sa"
pool-size: 30
Assuming that SomeDataSource
has regular JavaBean properties for the URL, the username, and the pool size, these settings are bound automatically before the DataSource
is made available to other components.
Spring Boot also provides a utility builder class, called DataSourceBuilder
, that can be used to create one of the standard data sources (if it is on the classpath).
The builder can detect the one to use based on what is available on the classpath.
It also auto-detects the driver based on the JDBC URL.
The following example shows how to create a data source by using a DataSourceBuilder
:
@Configuration(proxyBeanMethods = false)
public class MyDataSourceConfiguration {
@Bean
@ConfigurationProperties("app.datasource")
public DataSource dataSource() {
return DataSourceBuilder.create().build();
}
}
@Configuration(proxyBeanMethods = false)
class MyDataSourceConfiguration {
@Bean
@ConfigurationProperties("app.datasource")
fun dataSource(): DataSource {
return DataSourceBuilder.create().build()
}
}
To run an app with that DataSource
, all you need is the connection information.
Pool-specific settings can also be provided.
Check the implementation that is going to be used at runtime for more details.
The following example shows how to define a JDBC data source by setting properties:
app.datasource.url=jdbc:mysql://localhost/test
app.datasource.username=dbuser
app.datasource.password=dbpass
app.datasource.pool-size=30
app:
datasource:
url: "jdbc:mysql://localhost/test"
username: "dbuser"
password: "dbpass"
pool-size: 30
However, there is a catch.
Because the actual type of the connection pool is not exposed, no keys are generated in the metadata for your custom DataSource
and no completion is available in your IDE (because the DataSource
interface exposes no properties).
Also, if you happen to have Hikari on the classpath, this basic setup does not work, because Hikari has no url
property (but does have a jdbcUrl
property).
In that case, you must rewrite your configuration as follows:
app.datasource.jdbc-url=jdbc:mysql://localhost/test
app.datasource.username=dbuser
app.datasource.password=dbpass
app.datasource.pool-size=30
app:
datasource:
jdbc-url: "jdbc:mysql://localhost/test"
username: "dbuser"
password: "dbpass"
pool-size: 30
You can fix that by forcing the connection pool to use and return a dedicated implementation rather than DataSource
.
You cannot change the implementation at runtime, but the list of options will be explicit.
The following example shows how create a HikariDataSource
with DataSourceBuilder
:
@Configuration(proxyBeanMethods = false)
public class MyDataSourceConfiguration {
@Bean
@ConfigurationProperties("app.datasource")
public HikariDataSource dataSource() {
return DataSourceBuilder.create().type(HikariDataSource.class).build();
}
}
@Configuration(proxyBeanMethods = false)
class MyDataSourceConfiguration {
@Bean
@ConfigurationProperties("app.datasource")
fun dataSource(): HikariDataSource {
return DataSourceBuilder.create().type(HikariDataSource::class.java).build()
}
}
You can even go further by leveraging what DataSourceProperties
does for you — that is, by providing a default embedded database with a sensible username and password if no URL is provided.
You can easily initialize a DataSourceBuilder
from the state of any DataSourceProperties
object, so you could also inject the DataSource that Spring Boot creates automatically.
However, that would split your configuration into two namespaces: url
, username
, password
, type
, and driver
on spring.datasource
and the rest on your custom namespace (app.datasource
).
To avoid that, you can redefine a custom DataSourceProperties
on your custom namespace, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyDataSourceConfiguration {
@Bean
@Primary
@ConfigurationProperties("app.datasource")
public DataSourceProperties dataSourceProperties() {
return new DataSourceProperties();
}
@Bean
@ConfigurationProperties("app.datasource.configuration")
public HikariDataSource dataSource(DataSourceProperties properties) {
return properties.initializeDataSourceBuilder().type(HikariDataSource.class).build();
}
}
@Configuration(proxyBeanMethods = false)
class MyDataSourceConfiguration {
@Bean
@Primary
@ConfigurationProperties("app.datasource")
fun dataSourceProperties(): DataSourceProperties {
return DataSourceProperties()
}
@Bean
@ConfigurationProperties("app.datasource.configuration")
fun dataSource(properties: DataSourceProperties): HikariDataSource {
return properties.initializeDataSourceBuilder().type(HikariDataSource::class.java).build()
}
}
This setup puts you in sync with what Spring Boot does for you by default, except that a dedicated connection pool is chosen (in code) and its settings are exposed in the app.datasource.configuration
sub namespace.
Because DataSourceProperties
is taking care of the url
/jdbcUrl
translation for you, you can configure it as follows:
app.datasource.url=jdbc:mysql://localhost/test
app.datasource.username=dbuser
app.datasource.password=dbpass
app.datasource.configuration.maximum-pool-size=30
app:
datasource:
url: "jdbc:mysql://localhost/test"
username: "dbuser"
password: "dbpass"
configuration:
maximum-pool-size: 30
Spring Boot will expose Hikari-specific settings to spring.datasource.hikari .
This example uses a more generic configuration sub namespace as the example does not support multiple datasource implementations.
|
Because your custom configuration chooses to go with Hikari, app.datasource.type has no effect.
In practice, the builder is initialized with whatever value you might set there and then overridden by the call to .type() .
|
See “Configure a DataSource” in the “Spring Boot features” section and the DataSourceAutoConfiguration
class for more details.
18.8.2. Configure Two DataSources
If you need to configure multiple data sources, you can apply the same tricks that are described in the previous section.
You must, however, mark one of the DataSource
instances as @Primary
, because various auto-configurations down the road expect to be able to get one by type.
If you create your own DataSource
, the auto-configuration backs off.
In the following example, we provide the exact same feature set as the auto-configuration provides on the primary data source:
@Configuration(proxyBeanMethods = false)
public class MyDataSourcesConfiguration {
@Bean
@Primary
@ConfigurationProperties("app.datasource.first")
public DataSourceProperties firstDataSourceProperties() {
return new DataSourceProperties();
}
@Bean
@Primary
@ConfigurationProperties("app.datasource.first.configuration")
public HikariDataSource firstDataSource(DataSourceProperties firstDataSourceProperties) {
return firstDataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource.class).build();
}
@Bean
@ConfigurationProperties("app.datasource.second")
public BasicDataSource secondDataSource() {
return DataSourceBuilder.create().type(BasicDataSource.class).build();
}
}
@Configuration(proxyBeanMethods = false)
class MyDataSourcesConfiguration {
@Bean
@Primary
@ConfigurationProperties("app.datasource.first")
fun firstDataSourceProperties(): DataSourceProperties {
return DataSourceProperties()
}
@Bean
@Primary
@ConfigurationProperties("app.datasource.first.configuration")
fun firstDataSource(firstDataSourceProperties: DataSourceProperties): HikariDataSource {
return firstDataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource::class.java).build()
}
@Bean
@ConfigurationProperties("app.datasource.second")
fun secondDataSource(): BasicDataSource {
return DataSourceBuilder.create().type(BasicDataSource::class.java).build()
}
}
firstDataSourceProperties has to be flagged as @Primary so that the database initializer feature uses your copy (if you use the initializer).
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Both data sources are also bound for advanced customizations. For instance, you could configure them as follows:
app.datasource.first.url=jdbc:mysql://localhost/first
app.datasource.first.username=dbuser
app.datasource.first.password=dbpass
app.datasource.first.configuration.maximum-pool-size=30
app.datasource.second.url=jdbc:mysql://localhost/second
app.datasource.second.username=dbuser
app.datasource.second.password=dbpass
app.datasource.second.max-total=30
app:
datasource:
first:
url: "jdbc:mysql://localhost/first"
username: "dbuser"
password: "dbpass"
configuration:
maximum-pool-size: 30
second:
url: "jdbc:mysql://localhost/second"
username: "dbuser"
password: "dbpass"
max-total: 30
You can apply the same concept to the secondary DataSource
as well, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyCompleteDataSourcesConfiguration {
@Bean
@Primary
@ConfigurationProperties("app.datasource.first")
public DataSourceProperties firstDataSourceProperties() {
return new DataSourceProperties();
}
@Bean
@Primary
@ConfigurationProperties("app.datasource.first.configuration")
public HikariDataSource firstDataSource(DataSourceProperties firstDataSourceProperties) {
return firstDataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource.class).build();
}
@Bean
@ConfigurationProperties("app.datasource.second")
public DataSourceProperties secondDataSourceProperties() {
return new DataSourceProperties();
}
@Bean
@ConfigurationProperties("app.datasource.second.configuration")
public BasicDataSource secondDataSource(
@Qualifier("secondDataSourceProperties") DataSourceProperties secondDataSourceProperties) {
return secondDataSourceProperties.initializeDataSourceBuilder().type(BasicDataSource.class).build();
}
}
@Configuration(proxyBeanMethods = false)
class MyCompleteDataSourcesConfiguration {
@Bean
@Primary
@ConfigurationProperties("app.datasource.first")
fun firstDataSourceProperties(): DataSourceProperties {
return DataSourceProperties()
}
@Bean
@Primary
@ConfigurationProperties("app.datasource.first.configuration")
fun firstDataSource(firstDataSourceProperties: DataSourceProperties): HikariDataSource {
return firstDataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource::class.java).build()
}
@Bean
@ConfigurationProperties("app.datasource.second")
fun secondDataSourceProperties(): DataSourceProperties {
return DataSourceProperties()
}
@Bean
@ConfigurationProperties("app.datasource.second.configuration")
fun secondDataSource(secondDataSourceProperties: DataSourceProperties): BasicDataSource {
return secondDataSourceProperties.initializeDataSourceBuilder().type(BasicDataSource::class.java).build()
}
}
The preceding example configures two data sources on custom namespaces with the same logic as Spring Boot would use in auto-configuration.
Note that each configuration
sub namespace provides advanced settings based on the chosen implementation.
18.8.3. Use Spring Data Repositories
Spring Data can create implementations of @Repository
interfaces of various flavors.
Spring Boot handles all of that for you, as long as those @Repository
annotations are included in one of the auto-configuration packages, typically the package (or a sub-package) of your main application class that is annotated with @SpringBootApplication
or @EnableAutoConfiguration
.
For many applications, all you need is to put the right Spring Data dependencies on your classpath.
There is a spring-boot-starter-data-jpa
for JPA, spring-boot-starter-data-mongodb
for Mongodb, and various other starters for supported technologies.
To get started, create some repository interfaces to handle your @Entity
objects.
Spring Boot determines the location of your @Repository
definitions by scanning the auto-configuration packages.
For more control, use the @Enable…Repositories
annotations from Spring Data.
For more about Spring Data, see the Spring Data project page.
18.8.4. Separate @Entity Definitions from Spring Configuration
Spring Boot determines the location of your @Entity
definitions by scanning the auto-configuration packages.
For more control, use the @EntityScan
annotation, as shown in the following example:
@Configuration(proxyBeanMethods = false)
@EnableAutoConfiguration
@EntityScan(basePackageClasses = City.class)
public class MyApplication {
// ...
}
@Configuration(proxyBeanMethods = false)
@EnableAutoConfiguration
@EntityScan(basePackageClasses = [City::class])
class MyApplication {
// ...
}
18.8.5. Configure JPA Properties
Spring Data JPA already provides some vendor-independent configuration options (such as those for SQL logging), and Spring Boot exposes those options and a few more for Hibernate as external configuration properties. Some of them are automatically detected according to the context so you should not have to set them.
The spring.jpa.hibernate.ddl-auto
is a special case, because, depending on runtime conditions, it has different defaults.
If an embedded database is used and no schema manager (such as Liquibase or Flyway) is handling the DataSource
, it defaults to create-drop
.
In all other cases, it defaults to none
.
The dialect to use is detected by the JPA provider.
If you prefer to set the dialect yourself, set the spring.jpa.database-platform
property.
The most common options to set are shown in the following example:
spring.jpa.hibernate.naming.physical-strategy=com.example.MyPhysicalNamingStrategy
spring.jpa.show-sql=true
spring:
jpa:
hibernate:
naming:
physical-strategy: "com.example.MyPhysicalNamingStrategy"
show-sql: true
In addition, all properties in spring.jpa.properties.*
are passed through as normal JPA properties (with the prefix stripped) when the local EntityManagerFactory
is created.
You need to ensure that names defined under For example, if you want to configure Hibernate’s batch size you must use |
If you need to apply advanced customization to Hibernate properties, consider registering a HibernatePropertiesCustomizer bean that will be invoked prior to creating the EntityManagerFactory .
This takes precedence to anything that is applied by the auto-configuration.
|
18.8.6. Configure Hibernate Naming Strategy
Hibernate uses two different naming strategies to map names from the object model to the corresponding database names.
The fully qualified class name of the physical and the implicit strategy implementations can be configured by setting the spring.jpa.hibernate.naming.physical-strategy
and spring.jpa.hibernate.naming.implicit-strategy
properties, respectively.
Alternatively, if ImplicitNamingStrategy
or PhysicalNamingStrategy
beans are available in the application context, Hibernate will be automatically configured to use them.
By default, Spring Boot configures the physical naming strategy with CamelCaseToUnderscoresNamingStrategy
.
Using this strategy, all dots are replaced by underscores and camel casing is replaced by underscores as well.
Additionally, by default, all table names are generated in lower case.
For example, a TelephoneNumber
entity is mapped to the telephone_number
table.
If your schema requires mixed-case identifiers, define a custom CamelCaseToUnderscoresNamingStrategy
bean, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyHibernateConfiguration {
@Bean
public CamelCaseToUnderscoresNamingStrategy caseSensitivePhysicalNamingStrategy() {
return new CamelCaseToUnderscoresNamingStrategy() {
@Override
protected boolean isCaseInsensitive(JdbcEnvironment jdbcEnvironment) {
return false;
}
};
}
}
@Configuration(proxyBeanMethods = false)
class MyHibernateConfiguration {
@Bean
fun caseSensitivePhysicalNamingStrategy(): CamelCaseToUnderscoresNamingStrategy {
return object : CamelCaseToUnderscoresNamingStrategy() {
override fun isCaseInsensitive(jdbcEnvironment: JdbcEnvironment): Boolean {
return false
}
}
}
}
If you prefer to use Hibernate’s default instead, set the following property:
spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl
Alternatively, you can configure the following bean:
@Configuration(proxyBeanMethods = false)
class MyHibernateConfiguration {
@Bean
PhysicalNamingStrategyStandardImpl caseSensitivePhysicalNamingStrategy() {
return new PhysicalNamingStrategyStandardImpl();
}
}
@Configuration(proxyBeanMethods = false)
internal class MyHibernateConfiguration {
@Bean
fun caseSensitivePhysicalNamingStrategy(): PhysicalNamingStrategyStandardImpl {
return PhysicalNamingStrategyStandardImpl()
}
}
See HibernateJpaAutoConfiguration
and JpaBaseConfiguration
for more details.
18.8.7. Configure Hibernate Second-Level Caching
Hibernate second-level cache can be configured for a range of cache providers. Rather than configuring Hibernate to lookup the cache provider again, it is better to provide the one that is available in the context whenever possible.
To do this with JCache, first make sure that org.hibernate.orm:hibernate-jcache
is available on the classpath.
Then, add a HibernatePropertiesCustomizer
bean as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyHibernateSecondLevelCacheConfiguration {
@Bean
public HibernatePropertiesCustomizer hibernateSecondLevelCacheCustomizer(JCacheCacheManager cacheManager) {
return (properties) -> properties.put(ConfigSettings.CACHE_MANAGER, cacheManager.getCacheManager());
}
}
@Configuration(proxyBeanMethods = false)
class MyHibernateSecondLevelCacheConfiguration {
@Bean
fun hibernateSecondLevelCacheCustomizer(cacheManager: JCacheCacheManager): HibernatePropertiesCustomizer {
return HibernatePropertiesCustomizer { properties ->
properties[ConfigSettings.CACHE_MANAGER] = cacheManager.cacheManager
}
}
}
This customizer will configure Hibernate to use the same CacheManager
as the one that the application uses.
It is also possible to use separate CacheManager
instances.
For details, see the Hibernate user guide.
18.8.8. Use Dependency Injection in Hibernate Components
By default, Spring Boot registers a BeanContainer
implementation that uses the BeanFactory
so that converters and entity listeners can use regular dependency injection.
You can disable or tune this behavior by registering a HibernatePropertiesCustomizer
that removes or changes the hibernate.resource.beans.container
property.
18.8.9. Use a Custom EntityManagerFactory
To take full control of the configuration of the EntityManagerFactory
, you need to add a @Bean
named ‘entityManagerFactory’.
Spring Boot auto-configuration switches off its entity manager in the presence of a bean of that type.
18.8.10. Using Multiple EntityManagerFactories
If you need to use JPA against multiple data sources, you likely need one EntityManagerFactory
per data source.
The LocalContainerEntityManagerFactoryBean
from Spring ORM allows you to configure an EntityManagerFactory
for your needs.
You can also reuse JpaProperties
to bind settings for each EntityManagerFactory
, as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class MyEntityManagerFactoryConfiguration {
@Bean
@ConfigurationProperties("app.jpa.first")
public JpaProperties firstJpaProperties() {
return new JpaProperties();
}
@Bean
public LocalContainerEntityManagerFactoryBean firstEntityManagerFactory(DataSource firstDataSource,
JpaProperties firstJpaProperties) {
EntityManagerFactoryBuilder builder = createEntityManagerFactoryBuilder(firstJpaProperties);
return builder.dataSource(firstDataSource).packages(Order.class).persistenceUnit("firstDs").build();
}
private EntityManagerFactoryBuilder createEntityManagerFactoryBuilder(JpaProperties jpaProperties) {
JpaVendorAdapter jpaVendorAdapter = createJpaVendorAdapter(jpaProperties);
return new EntityManagerFactoryBuilder(jpaVendorAdapter, jpaProperties.getProperties(), null);
}
private JpaVendorAdapter createJpaVendorAdapter(JpaProperties jpaProperties) {
// ... map JPA properties as needed
return new HibernateJpaVendorAdapter();
}
}
@Configuration(proxyBeanMethods = false)
class MyEntityManagerFactoryConfiguration {
@Bean
@ConfigurationProperties("app.jpa.first")
fun firstJpaProperties(): JpaProperties {
return JpaProperties()
}
@Bean
fun firstEntityManagerFactory(
firstDataSource: DataSource?,
firstJpaProperties: JpaProperties
): LocalContainerEntityManagerFactoryBean {
val builder = createEntityManagerFactoryBuilder(firstJpaProperties)
return builder.dataSource(firstDataSource).packages(Order::class.java).persistenceUnit("firstDs").build()
}
private fun createEntityManagerFactoryBuilder(jpaProperties: JpaProperties): EntityManagerFactoryBuilder {
val jpaVendorAdapter = createJpaVendorAdapter(jpaProperties)
return EntityManagerFactoryBuilder(jpaVendorAdapter, jpaProperties.properties, null)
}
private fun createJpaVendorAdapter(jpaProperties: JpaProperties): JpaVendorAdapter {
// ... map JPA properties as needed
return HibernateJpaVendorAdapter()
}
}
The example above creates an EntityManagerFactory
using a DataSource
bean named firstDataSource
.
It scans entities located in the same package as Order
.
It is possible to map additional JPA properties using the app.first.jpa
namespace.
When you create a bean for LocalContainerEntityManagerFactoryBean yourself, any customization that was applied during the creation of the auto-configured LocalContainerEntityManagerFactoryBean is lost.
For example, in case of Hibernate, any properties under the spring.jpa.hibernate prefix will not be automatically applied to your LocalContainerEntityManagerFactoryBean .
If you were relying on these properties for configuring things like the naming strategy or the DDL mode, you will need to explicitly configure that when creating the LocalContainerEntityManagerFactoryBean bean.
|
You should provide a similar configuration for any additional data sources for which you need JPA access.
To complete the picture, you need to configure a JpaTransactionManager
for each EntityManagerFactory
as well.
Alternatively, you might be able to use a JTA transaction manager that spans both.
If you use Spring Data, you need to configure @EnableJpaRepositories
accordingly, as shown in the following examples:
@Configuration(proxyBeanMethods = false)
@EnableJpaRepositories(basePackageClasses = Order.class, entityManagerFactoryRef = "firstEntityManagerFactory")
public class OrderConfiguration {
}
@Configuration(proxyBeanMethods = false)
@EnableJpaRepositories(basePackageClasses = [Order::class], entityManagerFactoryRef = "firstEntityManagerFactory")
class OrderConfiguration
@Configuration(proxyBeanMethods = false)
@EnableJpaRepositories(basePackageClasses = Customer.class, entityManagerFactoryRef = "secondEntityManagerFactory")
public class CustomerConfiguration {
}
@Configuration(proxyBeanMethods = false)
@EnableJpaRepositories(basePackageClasses = [Customer::class], entityManagerFactoryRef = "secondEntityManagerFactory")
class CustomerConfiguration
18.8.11. Use a Traditional persistence.xml File
Spring Boot will not search for or use a META-INF/persistence.xml
by default.
If you prefer to use a traditional persistence.xml
, you need to define your own @Bean
of type LocalEntityManagerFactoryBean
(with an ID of ‘entityManagerFactory’) and set the persistence unit name there.
See JpaBaseConfiguration
for the default settings.
18.8.12. Use Spring Data JPA and Mongo Repositories
Spring Data JPA and Spring Data Mongo can both automatically create Repository
implementations for you.
If they are both present on the classpath, you might have to do some extra configuration to tell Spring Boot which repositories to create.
The most explicit way to do that is to use the standard Spring Data @EnableJpaRepositories
and @EnableMongoRepositories
annotations and provide the location of your Repository
interfaces.
There are also flags (spring.data.*.repositories.enabled
and spring.data.*.repositories.type
) that you can use to switch the auto-configured repositories on and off in external configuration.
Doing so is useful, for instance, in case you want to switch off the Mongo repositories and still use the auto-configured MongoTemplate
.
The same obstacle and the same features exist for other auto-configured Spring Data repository types (Elasticsearch, Redis, and others). To work with them, change the names of the annotations and flags accordingly.
18.8.13. Customize Spring Data’s Web Support
Spring Data provides web support that simplifies the use of Spring Data repositories in a web application.
Spring Boot provides properties in the spring.data.web
namespace for customizing its configuration.
Note that if you are using Spring Data REST, you must use the properties in the spring.data.rest
namespace instead.
18.8.14. Expose Spring Data Repositories as REST Endpoint
Spring Data REST can expose the Repository
implementations as REST endpoints for you,
provided Spring MVC has been enabled for the application.
Spring Boot exposes a set of useful properties (from the spring.data.rest
namespace) that customize the RepositoryRestConfiguration
.
If you need to provide additional customization, you should use a RepositoryRestConfigurer
bean.
If you do not specify any order on your custom RepositoryRestConfigurer , it runs after the one Spring Boot uses internally.
If you need to specify an order, make sure it is higher than 0.
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18.8.15. Configure a Component that is Used by JPA
If you want to configure a component that JPA uses, then you need to ensure that the component is initialized before JPA. When the component is auto-configured, Spring Boot takes care of this for you. For example, when Flyway is auto-configured, Hibernate is configured to depend upon Flyway so that Flyway has a chance to initialize the database before Hibernate tries to use it.
If you are configuring a component yourself, you can use an EntityManagerFactoryDependsOnPostProcessor
subclass as a convenient way of setting up the necessary dependencies.
For example, if you use Hibernate Search with Elasticsearch as its index manager, any EntityManagerFactory
beans must be configured to depend on the elasticsearchClient
bean, as shown in the following example:
/**
* {@link EntityManagerFactoryDependsOnPostProcessor} that ensures that
* {@link EntityManagerFactory} beans depend on the {@code elasticsearchClient} bean.
*/
@Component
public class ElasticsearchEntityManagerFactoryDependsOnPostProcessor
extends EntityManagerFactoryDependsOnPostProcessor {
public ElasticsearchEntityManagerFactoryDependsOnPostProcessor() {
super("elasticsearchClient");
}
}
@Component
class ElasticsearchEntityManagerFactoryDependsOnPostProcessor :
EntityManagerFactoryDependsOnPostProcessor("elasticsearchClient")
18.8.16. Configure jOOQ with Two DataSources
If you need to use jOOQ with multiple data sources, you should create your own DSLContext
for each one.
See JooqAutoConfiguration for more details.
In particular, JooqExceptionTranslator and SpringTransactionProvider can be reused to provide similar features to what the auto-configuration does with a single DataSource .
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18.9. Database Initialization
An SQL database can be initialized in different ways depending on what your stack is. Of course, you can also do it manually, provided the database is a separate process. It is recommended to use a single mechanism for schema generation.
18.9.1. Initialize a Database Using JPA
JPA has features for DDL generation, and these can be set up to run on startup against the database. This is controlled through two external properties:
-
spring.jpa.generate-ddl
(boolean) switches the feature on and off and is vendor independent. -
spring.jpa.hibernate.ddl-auto
(enum) is a Hibernate feature that controls the behavior in a more fine-grained way. This feature is described in more detail later in this guide.
18.9.2. Initialize a Database Using Hibernate
You can set spring.jpa.hibernate.ddl-auto
explicitly and the standard Hibernate property values are none
, validate
, update
, create
, and create-drop
.
Spring Boot chooses a default value for you based on whether it thinks your database is embedded.
It defaults to create-drop
if no schema manager has been detected or none
in all other cases.
An embedded database is detected by looking at the Connection
type and JDBC url.
hsqldb
, h2
, and derby
are candidates, and others are not.
Be careful when switching from in-memory to a ‘real’ database that you do not make assumptions about the existence of the tables and data in the new platform.
You either have to set ddl-auto
explicitly or use one of the other mechanisms to initialize the database.
You can output the schema creation by enabling the org.hibernate.SQL logger.
This is done for you automatically if you enable the debug mode.
|
In addition, a file named import.sql
in the root of the classpath is executed on startup if Hibernate creates the schema from scratch (that is, if the ddl-auto
property is set to create
or create-drop
).
This can be useful for demos and for testing if you are careful but is probably not something you want to be on the classpath in production.
It is a Hibernate feature (and has nothing to do with Spring).
18.9.3. Initialize a Database Using Basic SQL Scripts
Spring Boot can automatically create the schema (DDL scripts) of your JDBC DataSource
or R2DBC ConnectionFactory
and initialize its data (DML scripts).
By default, it loads schema scripts from optional:classpath*:schema.sql
and data scripts from optional:classpath*:data.sql
.
The locations of these schema and data scripts can customized using spring.sql.init.schema-locations
and spring.sql.init.data-locations
respectively.
The optional:
prefix means that the application will start when the files do not exist.
To have the application fail to start when the files are absent, remove the optional:
prefix.
In addition, Spring Boot processes the optional:classpath*:schema-${platform}.sql
and optional:classpath*:data-${platform}.sql
files (if present), where ${platform}
is the value of spring.sql.init.platform
.
This allows you to switch to database-specific scripts if necessary.
For example, you might choose to set it to the vendor name of the database (hsqldb
, h2
, oracle
, mysql
, postgresql
, and so on).
By default, SQL database initialization is only performed when using an embedded in-memory database.
To always initialize an SQL database, irrespective of its type, set spring.sql.init.mode
to always
.
Similarly, to disable initialization, set spring.sql.init.mode
to never
.
By default, Spring Boot enables the fail-fast feature of its script-based database initializer.
This means that, if the scripts cause exceptions, the application fails to start.
You can tune that behavior by setting spring.sql.init.continue-on-error
.
Script-based DataSource
initialization is performed, by default, before any JPA EntityManagerFactory
beans are created.
schema.sql
can be used to create the schema for JPA-managed entities and data.sql
can be used to populate it.
While we do not recommend using multiple data source initialization technologies, if you want script-based DataSource
initialization to be able to build upon the schema creation performed by Hibernate, set spring.jpa.defer-datasource-initialization
to true
.
This will defer data source initialization until after any EntityManagerFactory
beans have been created and initialized.
schema.sql
can then be used to make additions to any schema creation performed by Hibernate and data.sql
can be used to populate it.
The initialization scripts support -- for single line comments and /* */ for block comments.
Other comment formats are not supported.
|
If you are using a Higher-level Database Migration Tool, like Flyway or Liquibase, you should use them alone to create and initialize the schema.
Using the basic schema.sql
and data.sql
scripts alongside Flyway or Liquibase is not recommended and support will be removed in a future release.
18.9.4. Initialize a Spring Batch Database
If you use Spring Batch, it comes pre-packaged with SQL initialization scripts for most popular database platforms. Spring Boot can detect your database type and execute those scripts on startup. If you use an embedded database, this happens by default. You can also enable it for any database type, as shown in the following example:
spring.batch.jdbc.initialize-schema=always
spring:
batch:
jdbc:
initialize-schema: "always"
You can also switch off the initialization explicitly by setting spring.batch.jdbc.initialize-schema
to never
.
18.9.5. Use a Higher-level Database Migration Tool
Execute Flyway Database Migrations on Startup
To automatically run Flyway database migrations on startup, add the org.flywaydb:flyway-core
to your classpath.
Typically, migrations are scripts in the form V<VERSION>__<NAME>.sql
(with <VERSION>
an underscore-separated version, such as ‘1’ or ‘2_1’).
By default, they are in a directory called classpath:db/migration
, but you can modify that location by setting spring.flyway.locations
.
This is a comma-separated list of one or more classpath:
or filesystem:
locations.
For example, the following configuration would search for scripts in both the default classpath location and the /opt/migration
directory:
spring.flyway.locations=classpath:db/migration,filesystem:/opt/migration
spring:
flyway:
locations: "classpath:db/migration,filesystem:/opt/migration"
You can also add a special {vendor}
placeholder to use vendor-specific scripts.
Assume the following:
spring.flyway.locations=classpath:db/migration/{vendor}
spring:
flyway:
locations: "classpath:db/migration/{vendor}"
Rather than using db/migration
, the preceding configuration sets the directory to use according to the type of the database (such as db/migration/mysql
for MySQL).
The list of supported databases is available in DatabaseDriver
.
Migrations can also be written in Java.
Flyway will be auto-configured with any beans that implement JavaMigration
.
FlywayProperties
provides most of Flyway’s settings and a small set of additional properties that can be used to disable the migrations or switch off the location checking.
If you need more control over the configuration, consider registering a FlywayConfigurationCustomizer
bean.
Spring Boot calls Flyway.migrate()
to perform the database migration.
If you would like more control, provide a @Bean
that implements FlywayMigrationStrategy
.
Flyway supports SQL and Java callbacks.
To use SQL-based callbacks, place the callback scripts in the classpath:db/migration
directory.
To use Java-based callbacks, create one or more beans that implement Callback
.
Any such beans are automatically registered with Flyway
.
They can be ordered by using @Order
or by implementing Ordered
.
Beans that implement the deprecated FlywayCallback
interface can also be detected, however they cannot be used alongside Callback
beans.
By default, Flyway autowires the (@Primary
) DataSource
in your context and uses that for migrations.
If you like to use a different DataSource
, you can create one and mark its @Bean
as @FlywayDataSource
.
If you do so and want two data sources, remember to create another one and mark it as @Primary
.
Alternatively, you can use Flyway’s native DataSource
by setting spring.flyway.[url,user,password]
in external properties.
Setting either spring.flyway.url
or spring.flyway.user
is sufficient to cause Flyway to use its own DataSource
.
If any of the three properties has not been set, the value of its equivalent spring.datasource
property will be used.
You can also use Flyway to provide data for specific scenarios.
For example, you can place test-specific migrations in src/test/resources
and they are run only when your application starts for testing.
Also, you can use profile-specific configuration to customize spring.flyway.locations
so that certain migrations run only when a particular profile is active.
For example, in application-dev.properties
, you might specify the following setting:
spring.flyway.locations=classpath:/db/migration,classpath:/dev/db/migration
spring:
flyway:
locations: "classpath:/db/migration,classpath:/dev/db/migration"
With that setup, migrations in dev/db/migration
run only when the dev
profile is active.
Execute Liquibase Database Migrations on Startup
To automatically run Liquibase database migrations on startup, add the org.liquibase:liquibase-core
to your classpath.
When you add the |
By default, the master change log is read from db/changelog/db.changelog-master.yaml
, but you can change the location by setting spring.liquibase.change-log
.
In addition to YAML, Liquibase also supports JSON, XML, and SQL change log formats.
By default, Liquibase autowires the (@Primary
) DataSource
in your context and uses that for migrations.
If you need to use a different DataSource
, you can create one and mark its @Bean
as @LiquibaseDataSource
.
If you do so and you want two data sources, remember to create another one and mark it as @Primary
.
Alternatively, you can use Liquibase’s native DataSource
by setting spring.liquibase.[driver-class-name,url,user,password]
in external properties.
Setting either spring.liquibase.url
or spring.liquibase.user
is sufficient to cause Liquibase to use its own DataSource
.
If any of the three properties has not been set, the value of its equivalent spring.datasource
property will be used.
See LiquibaseProperties
for details about available settings such as contexts, the default schema, and others.
Use Flyway for test-only migrations
If you want to create Flyway migrations which populate your test database, place them in src/test/resources/db/migration
.
A file named, for example, src/test/resources/db/migration/V9999__test-data.sql
will be executed after your production migrations and only if you’re running the tests.
You can use this file to create the needed test data.
This file will not be packaged in your uber jar or your container.
Use Liquibase for test-only migrations
If you want to create Liquibase migrations which populate your test database, you have to create a test changelog which also includes the production changelog.
First, you need to configure Liquibase to use a different changelog when running the tests.
One way to do this is to create a Spring Boot test
profile and put the Liquibase properties in there.
For that, create a file named src/test/resources/application-test.properties
and put the following property in there:
spring.liquibase.change-log=classpath:/db/changelog/db.changelog-test.yaml
spring:
liquibase:
change-log: "classpath:/db/changelog/db.changelog-test.yaml"
This configures Liquibase to use a different changelog when running in the test
profile.
Now create the changelog file at src/test/resources/db/changelog/db.changelog-test.yaml
:
databaseChangeLog:
- include:
file: classpath:/db/changelog/db.changelog-master.yaml
- changeSet:
runOrder: "last"
id: "test"
changes:
# Insert your changes here
This changelog will be used when the tests are run and it will not be packaged in your uber jar or your container.
It includes the production changelog and then declares a new changeset, whose runOrder: last
setting specifies that it runs after all the production changesets have been run.
You can now use for example the insert changeset to insert data or the sql changeset to execute SQL directly.
The last thing to do is to configure Spring Boot to activate the test
profile when running tests.
To do this, you can add the @ActiveProfiles("test")
annotation to your @SpringBootTest
annotated test classes.
18.9.6. Depend Upon an Initialized Database
Database initialization is performed while the application is starting up as part of application context refresh. To allow an initialized database to be accessed during startup, beans that act as database initializers and beans that require that database to have been initialized are detected automatically. Beans whose initialization depends upon the database having been initialized are configured to depend upon those that initialize it. If, during startup, your application tries to access the database and it has not been initialized, you can configure additional detection of beans that initialize the database and require the database to have been initialized.
Detect a Database Initializer
Spring Boot will automatically detect beans of the following types that initialize an SQL database:
-
DataSourceScriptDatabaseInitializer
-
EntityManagerFactory
-
Flyway
-
FlywayMigrationInitializer
-
R2dbcScriptDatabaseInitializer
-
SpringLiquibase
If you are using a third-party starter for a database initialization library, it may provide a detector such that beans of other types are also detected automatically.
To have other beans be detected, register an implementation of DatabaseInitializerDetector
in META-INF/spring.factories
.
Detect a Bean That Depends On Database Initialization
Spring Boot will automatically detect beans of the following types that depends upon database initialization:
-
AbstractEntityManagerFactoryBean
(unlessspring.jpa.defer-datasource-initialization
is set totrue
) -
DSLContext
(jOOQ) -
EntityManagerFactory
(unlessspring.jpa.defer-datasource-initialization
is set totrue
) -
JdbcClient
-
JdbcOperations
-
NamedParameterJdbcOperations
If you are using a third-party starter data access library, it may provide a detector such that beans of other types are also detected automatically.
To have other beans be detected, register an implementation of DependsOnDatabaseInitializationDetector
in META-INF/spring.factories
.
Alternatively, annotate the bean’s class or its @Bean
method with @DependsOnDatabaseInitialization
.
18.10. NoSQL
Spring Boot offers a number of starters that support NoSQL technologies. This section answers questions that arise from using NoSQL with Spring Boot.
18.10.1. Use Jedis Instead of Lettuce
By default, the Spring Boot starter (spring-boot-starter-data-redis
) uses Lettuce.
You need to exclude that dependency and include the Jedis one instead.
Spring Boot manages both of these dependencies so you can switch to Jedis without specifying a version.
The following example shows how to do so in Maven:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis</artifactId>
<exclusions>
<exclusion>
<groupId>io.lettuce</groupId>
<artifactId>lettuce-core</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
</dependency>
The following example shows how to do so in Gradle:
dependencies {
implementation('org.springframework.boot:spring-boot-starter-data-redis') {
exclude group: 'io.lettuce', module: 'lettuce-core'
}
implementation 'redis.clients:jedis'
// ...
}
18.11. Messaging
Spring Boot offers a number of starters to support messaging. This section answers questions that arise from using messaging with Spring Boot.
18.11.1. Disable Transacted JMS Session
If your JMS broker does not support transacted sessions, you have to disable the support of transactions altogether.
If you create your own JmsListenerContainerFactory
, there is nothing to do, since, by default it cannot be transacted.
If you want to use the DefaultJmsListenerContainerFactoryConfigurer
to reuse Spring Boot’s default, you can disable transacted sessions, as follows:
@Configuration(proxyBeanMethods = false)
public class MyJmsConfiguration {
@Bean
public DefaultJmsListenerContainerFactory jmsListenerContainerFactory(ConnectionFactory connectionFactory,
DefaultJmsListenerContainerFactoryConfigurer configurer) {
DefaultJmsListenerContainerFactory listenerFactory = new DefaultJmsListenerContainerFactory();
configurer.configure(listenerFactory, connectionFactory);
listenerFactory.setTransactionManager(null);
listenerFactory.setSessionTransacted(false);
return listenerFactory;
}
}
@Configuration(proxyBeanMethods = false)
class MyJmsConfiguration {
@Bean
fun jmsListenerContainerFactory(connectionFactory: ConnectionFactory?,
configurer: DefaultJmsListenerContainerFactoryConfigurer): DefaultJmsListenerContainerFactory {
val listenerFactory = DefaultJmsListenerContainerFactory()
configurer.configure(listenerFactory, connectionFactory)
listenerFactory.setTransactionManager(null)
listenerFactory.setSessionTransacted(false)
return listenerFactory
}
}
The preceding example overrides the default factory, and it should be applied to any other factory that your application defines, if any.
18.12. Batch Applications
A number of questions often arise when people use Spring Batch from within a Spring Boot application. This section addresses those questions.
18.12.1. Specifying a Batch Data Source
By default, batch applications require a DataSource
to store job details.
Spring Batch expects a single DataSource
by default.
To have it use a DataSource
other than the application’s main DataSource
, declare a DataSource
bean, annotating its @Bean
method with @BatchDataSource
.
If you do so and want two data sources, remember to mark the other one @Primary
.
To take greater control, add @EnableBatchProcessing
to one of your @Configuration
classes or extend DefaultBatchConfiguration
.
See the Javadoc of @EnableBatchProcessing
and DefaultBatchConfiguration
for more details.
For more info about Spring Batch, see the Spring Batch project page.
18.12.2. Running Spring Batch Jobs on Startup
Spring Batch auto-configuration is enabled by adding spring-boot-starter-batch
to your application’s classpath.
If a single Job
is found in the application context, it is executed on startup (see JobLauncherApplicationRunner
for details).
If multiple Job
beans are found, the job that should be executed must be specified using spring.batch.job.name
.
To disable running a Job
found in the application context, set the spring.batch.job.enabled
to false
.
See BatchAutoConfiguration for more details.
18.12.3. Running From the Command Line
Spring Boot converts any command line argument starting with --
to a property to add to the Environment
, see accessing command line properties.
This should not be used to pass arguments to batch jobs.
To specify batch arguments on the command line, use the regular format (that is without --
), as shown in the following example:
$ java -jar myapp.jar someParameter=someValue anotherParameter=anotherValue
If you specify a property of the Environment
on the command line, it is ignored by the job.
Consider the following command:
$ java -jar myapp.jar --server.port=7070 someParameter=someValue
This provides only one argument to the batch job: someParameter=someValue
.
18.12.4. Restarting a stopped or failed Job
To restart a failed Job
, all parameters (identifying and non-identifying) must be re-specified on the command line.
Non-identifying parameters are not copied from the previous execution.
This allows them to be modified or removed.
When you’re using a custom JobParametersIncrementer , you have to gather all parameters managed by the incrementer to restart a failed execution.
|
18.12.5. Storing the Job Repository
Spring Batch requires a data store for the Job
repository.
If you use Spring Boot, you must use an actual database.
Note that it can be an in-memory database, see Configuring a Job Repository.
18.13. Actuator
Spring Boot includes the Spring Boot Actuator. This section answers questions that often arise from its use.
18.13.1. Change the HTTP Port or Address of the Actuator Endpoints
In a standalone application, the Actuator HTTP port defaults to the same as the main HTTP port.
To make the application listen on a different port, set the external property: management.server.port
.
To listen on a completely different network address (such as when you have an internal network for management and an external one for user applications), you can also set management.server.address
to a valid IP address to which the server is able to bind.
For more detail, see the ManagementServerProperties
source code and “Customizing the Management Server Port” in the “Production-ready features” section.
18.13.2. Customize the ‘whitelabel’ Error Page
Spring Boot installs a ‘whitelabel’ error page that you see in a browser client if you encounter a server error (machine clients consuming JSON and other media types should see a sensible response with the right error code).
Set server.error.whitelabel.enabled=false to switch the default error page off.
Doing so restores the default of the servlet container that you are using.
Note that Spring Boot still tries to resolve the error view, so you should probably add your own error page rather than disabling it completely.
|
Overriding the error page with your own depends on the templating technology that you use.
For example, if you use Thymeleaf, you can add an error.html
template.
If you use FreeMarker, you can add an error.ftlh
template.
In general, you need a View
that resolves with a name of error
or a @Controller
that handles the /error
path.
Unless you replaced some of the default configuration, you should find a BeanNameViewResolver
in your ApplicationContext
, so a @Bean
named error
would be one way of doing that.
See ErrorMvcAutoConfiguration
for more options.
See also the section on “Error Handling” for details of how to register handlers in the servlet container.
18.13.3. Customizing Sanitization
To take control over the sanitization, define a SanitizingFunction
bean.
The SanitizableData
with which the function is called provides access to the key and value as well as the PropertySource
from which they came.
This allows you to, for example, sanitize every value that comes from a particular property source.
Each SanitizingFunction
is called in order until a function changes the value of the sanitizable data.
18.13.4. Map Health Indicators to Micrometer Metrics
Spring Boot health indicators return a Status
type to indicate the overall system health.
If you want to monitor or alert on levels of health for a particular application, you can export these statuses as metrics with Micrometer.
By default, the status codes “UP”, “DOWN”, “OUT_OF_SERVICE” and “UNKNOWN” are used by Spring Boot.
To export these, you will need to convert these states to some set of numbers so that they can be used with a Micrometer Gauge
.
The following example shows one way to write such an exporter:
@Configuration(proxyBeanMethods = false)
public class MyHealthMetricsExportConfiguration {
public MyHealthMetricsExportConfiguration(MeterRegistry registry, HealthEndpoint healthEndpoint) {
// This example presumes common tags (such as the app) are applied elsewhere
Gauge.builder("health", healthEndpoint, this::getStatusCode).strongReference(true).register(registry);
}
private int getStatusCode(HealthEndpoint health) {
Status status = health.health().getStatus();
if (Status.UP.equals(status)) {
return 3;
}
if (Status.OUT_OF_SERVICE.equals(status)) {
return 2;
}
if (Status.DOWN.equals(status)) {
return 1;
}
return 0;
}
}
@Configuration(proxyBeanMethods = false)
class MyHealthMetricsExportConfiguration(registry: MeterRegistry, healthEndpoint: HealthEndpoint) {
init {
// This example presumes common tags (such as the app) are applied elsewhere
Gauge.builder("health", healthEndpoint) { health ->
getStatusCode(health).toDouble()
}.strongReference(true).register(registry)
}
private fun getStatusCode(health: HealthEndpoint) = when (health.health().status) {
Status.UP -> 3
Status.OUT_OF_SERVICE -> 2
Status.DOWN -> 1
else -> 0
}
}
18.14. Security
This section addresses questions about security when working with Spring Boot, including questions that arise from using Spring Security with Spring Boot.
For more about Spring Security, see the Spring Security project page.
18.14.1. Switch off the Spring Boot Security Configuration
If you define a @Configuration
with a SecurityFilterChain
bean in your application, it switches off the default webapp security settings in Spring Boot.
18.14.2. Change the UserDetailsService and Add User Accounts
If you provide a @Bean
of type AuthenticationManager
, AuthenticationProvider
, or UserDetailsService
, the default @Bean
for InMemoryUserDetailsManager
is not created.
This means you have the full feature set of Spring Security available (such as various authentication options).
The easiest way to add user accounts is to provide your own UserDetailsService
bean.
18.14.3. Enable HTTPS When Running behind a Proxy Server
Ensuring that all your main endpoints are only available over HTTPS is an important chore for any application.
If you use Tomcat as a servlet container, then Spring Boot adds Tomcat’s own RemoteIpValve
automatically if it detects some environment settings, and you should be able to rely on the HttpServletRequest
to report whether it is secure or not (even downstream of a proxy server that handles the real SSL termination).
The standard behavior is determined by the presence or absence of certain request headers (x-forwarded-for
and x-forwarded-proto
), whose names are conventional, so it should work with most front-end proxies.
You can switch on the valve by adding some entries to application.properties
, as shown in the following example:
server.tomcat.remoteip.remote-ip-header=x-forwarded-for
server.tomcat.remoteip.protocol-header=x-forwarded-proto
server:
tomcat:
remoteip:
remote-ip-header: "x-forwarded-for"
protocol-header: "x-forwarded-proto"
(The presence of either of those properties switches on the valve.
Alternatively, you can add the RemoteIpValve
by customizing the TomcatServletWebServerFactory
using a WebServerFactoryCustomizer
bean.)
To configure Spring Security to require a secure channel for all (or some) requests, consider adding your own SecurityFilterChain
bean that adds the following HttpSecurity
configuration:
@Configuration
public class MySecurityConfig {
@Bean
public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
// Customize the application security ...
http.requiresChannel((channel) -> channel.anyRequest().requiresSecure());
return http.build();
}
}
@Configuration
class MySecurityConfig {
@Bean
fun securityFilterChain(http: HttpSecurity): SecurityFilterChain {
// Customize the application security ...
http.requiresChannel { requests -> requests.anyRequest().requiresSecure() }
return http.build()
}
}
18.15. Hot Swapping
Spring Boot supports hot swapping. This section answers questions about how it works.
18.15.1. Reload Static Content
There are several options for hot reloading.
The recommended approach is to use spring-boot-devtools
, as it provides additional development-time features, such as support for fast application restarts and LiveReload as well as sensible development-time configuration (such as template caching).
Devtools works by monitoring the classpath for changes.
This means that static resource changes must be "built" for the change to take effect.
By default, this happens automatically in Eclipse when you save your changes.
In IntelliJ IDEA, the Make Project command triggers the necessary build.
Due to the default restart exclusions, changes to static resources do not trigger a restart of your application.
They do, however, trigger a live reload.
Alternatively, running in an IDE (especially with debugging on) is a good way to do development (all modern IDEs allow reloading of static resources and usually also allow hot-swapping of Java class changes).
Finally, the Maven and Gradle plugins can be configured (see the addResources
property) to support running from the command line with reloading of static files directly from source.
You can use that with an external css/js compiler process if you are writing that code with higher-level tools.
18.15.2. Reload Templates without Restarting the Container
Most of the templating technologies supported by Spring Boot include a configuration option to disable caching (described later in this document).
If you use the spring-boot-devtools
module, these properties are automatically configured for you at development time.
Thymeleaf Templates
If you use Thymeleaf, set spring.thymeleaf.cache
to false
.
See ThymeleafAutoConfiguration
for other Thymeleaf customization options.
FreeMarker Templates
If you use FreeMarker, set spring.freemarker.cache
to false
.
See FreeMarkerAutoConfiguration
for other FreeMarker customization options.
Groovy Templates
If you use Groovy templates, set spring.groovy.template.cache
to false
.
See GroovyTemplateAutoConfiguration
for other Groovy customization options.
18.15.3. Fast Application Restarts
The spring-boot-devtools
module includes support for automatic application restarts.
While not as fast as technologies such as JRebel it is usually significantly faster than a “cold start”.
You should probably give it a try before investigating some of the more complex reload options discussed later in this document.
For more details, see the Developer Tools section.
18.16. Testing
Spring Boot includes a number of testing utilities and support classes as well as a dedicated starter that provides common test dependencies. This section answers common questions about testing.
18.16.1. Testing With Spring Security
Spring Security provides support for running tests as a specific user.
For example, the test in the snippet below will run with an authenticated user that has the ADMIN
role.
@WebMvcTest(UserController.class)
class MySecurityTests {
@Autowired
private MockMvc mvc;
@Test
@WithMockUser(roles = "ADMIN")
void requestProtectedUrlWithUser() throws Exception {
this.mvc.perform(get("/"));
}
}
@WebMvcTest(UserController::class)
class MySecurityTests(@Autowired val mvc: MockMvc) {
@Test
@WithMockUser(roles = ["ADMIN"])
fun requestProtectedUrlWithUser() {
mvc.perform(MockMvcRequestBuilders.get("/"))
}
}
Spring Security provides comprehensive integration with Spring MVC Test and this can also be used when testing controllers using the @WebMvcTest
slice and MockMvc
.
For additional details on Spring Security’s testing support, see Spring Security’s reference documentation.
18.16.2. Structure @Configuration
classes for inclusion in slice tests
Slice tests work by restricting Spring Framework’s component scanning to a limited set of components based on their type.
For any beans that are not created through component scanning, for example, beans that are created using the @Bean
annotation, slice tests will not be able to include/exclude them from the application context.
Consider this example:
@Configuration(proxyBeanMethods = false)
public class MyConfiguration {
@Bean
public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
http.authorizeHttpRequests((requests) -> requests.anyRequest().authenticated());
return http.build();
}
@Bean
@ConfigurationProperties("app.datasource.second")
public BasicDataSource secondDataSource() {
return DataSourceBuilder.create().type(BasicDataSource.class).build();
}
}
For a @WebMvcTest
for an application with the above @Configuration
class, you might expect to have the SecurityFilterChain
bean in the application context so that you can test if your controller endpoints are secured properly.
However, MyConfiguration
is not picked up by @WebMvcTest’s component scanning filter because it doesn’t match any of the types specified by the filter.
You can include the configuration explicitly by annotating the test class with @Import(MyConfiguration.class)
.
This will load all the beans in MyConfiguration
including the BasicDataSource
bean which isn’t required when testing the web tier.
Splitting the configuration class into two will enable importing just the security configuration.
@Configuration(proxyBeanMethods = false)
public class MySecurityConfiguration {
@Bean
public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
http.authorizeHttpRequests((requests) -> requests.anyRequest().authenticated());
return http.build();
}
}
@Configuration(proxyBeanMethods = false)
public class MyDatasourceConfiguration {
@Bean
@ConfigurationProperties("app.datasource.second")
public BasicDataSource secondDataSource() {
return DataSourceBuilder.create().type(BasicDataSource.class).build();
}
}
Having a single configuration class can be inefficient when beans of a certain domain need to be included in slice tests. Instead, structuring the application’s configuration as multiple granular classes with beans for a specific domain can enable importing them only for specific slice tests.
18.17. Build
Spring Boot includes build plugins for Maven and Gradle. This section answers common questions about these plugins.
18.17.1. Generate Build Information
Both the Maven plugin and the Gradle plugin allow generating build information containing the coordinates, name, and version of the project.
The plugins can also be configured to add additional properties through configuration.
When such a file is present, Spring Boot auto-configures a BuildProperties
bean.
To generate build information with Maven, add an execution for the build-info
goal, as shown in the following example:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>3.2.0-SNAPSHOT</version>
<executions>
<execution>
<goals>
<goal>build-info</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
See the Spring Boot Maven Plugin documentation for more details. |
The following example does the same with Gradle:
springBoot {
buildInfo()
}
See the Spring Boot Gradle Plugin documentation for more details. |
18.17.2. Generate Git Information
Both Maven and Gradle allow generating a git.properties
file containing information about the state of your git
source code repository when the project was built.
For Maven users, the spring-boot-starter-parent
POM includes a pre-configured plugin to generate a git.properties
file.
To use it, add the following declaration for the Git Commit Id Plugin
to your POM:
<build>
<plugins>
<plugin>
<groupId>io.github.git-commit-id</groupId>
<artifactId>git-commit-id-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
Gradle users can achieve the same result by using the gradle-git-properties
plugin, as shown in the following example:
plugins {
id "com.gorylenko.gradle-git-properties" version "2.4.1"
}
Both the Maven and Gradle plugins allow the properties that are included in git.properties
to be configured.
The commit time in git.properties is expected to match the following format: yyyy-MM-dd’T’HH:mm:ssZ .
This is the default format for both plugins listed above.
Using this format lets the time be parsed into a Date and its format, when serialized to JSON, to be controlled by Jackson’s date serialization configuration settings.
|
18.17.3. Customize Dependency Versions
The spring-boot-dependencies
POM manages the versions of common dependencies.
The Spring Boot plugins for Maven and Gradle allow these managed dependency versions to be customized using build properties.
Each Spring Boot release is designed and tested against this specific set of third-party dependencies. Overriding versions may cause compatibility issues. |
To override dependency versions with Maven, see this section of the Maven plugin’s documentation.
To override dependency versions in Gradle, see this section of the Gradle plugin’s documentation.
18.17.4. Create an Executable JAR with Maven
The spring-boot-maven-plugin
can be used to create an executable “fat” JAR.
If you use the spring-boot-starter-parent
POM, you can declare the plugin and your jars are repackaged as follows:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
If you do not use the parent POM, you can still use the plugin.
However, you must additionally add an <executions>
section, as follows:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>3.2.0-SNAPSHOT</version>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
See the plugin documentation for full usage details.
18.17.5. Use a Spring Boot Application as a Dependency
Like a war file, a Spring Boot application is not intended to be used as a dependency. If your application contains classes that you want to share with other projects, the recommended approach is to move that code into a separate module. The separate module can then be depended upon by your application and other projects.
If you cannot rearrange your code as recommended above, Spring Boot’s Maven and Gradle plugins must be configured to produce a separate artifact that is suitable for use as a dependency.
The executable archive cannot be used as a dependency as the executable jar format packages application classes in BOOT-INF/classes
.
This means that they cannot be found when the executable jar is used as a dependency.
To produce the two artifacts, one that can be used as a dependency and one that is executable, a classifier must be specified. This classifier is applied to the name of the executable archive, leaving the default archive for use as a dependency.
To configure a classifier of exec
in Maven, you can use the following configuration:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<classifier>exec</classifier>
</configuration>
</plugin>
</plugins>
</build>
18.17.6. Extract Specific Libraries When an Executable Jar Runs
Most nested libraries in an executable jar do not need to be unpacked in order to run.
However, certain libraries can have problems.
For example, JRuby includes its own nested jar support, which assumes that the jruby-complete.jar
is always directly available as a file in its own right.
To deal with any problematic libraries, you can flag that specific nested jars should be automatically unpacked when the executable jar first runs.
Such nested jars are written beneath the temporary directory identified by the java.io.tmpdir
system property.
Care should be taken to ensure that your operating system is configured so that it will not delete the jars that have been unpacked to the temporary directory while the application is still running. |
For example, to indicate that JRuby should be flagged for unpacking by using the Maven Plugin, you would add the following configuration:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<requiresUnpack>
<dependency>
<groupId>org.jruby</groupId>
<artifactId>jruby-complete</artifactId>
</dependency>
</requiresUnpack>
</configuration>
</plugin>
</plugins>
</build>
18.17.7. Create a Non-executable JAR with Exclusions
Often, if you have an executable and a non-executable jar as two separate build products, the executable version has additional configuration files that are not needed in a library jar.
For example, the application.yaml
configuration file might be excluded from the non-executable JAR.
In Maven, the executable jar must be the main artifact and you can add a classified jar for the library, as follows:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<executions>
<execution>
<id>lib</id>
<phase>package</phase>
<goals>
<goal>jar</goal>
</goals>
<configuration>
<classifier>lib</classifier>
<excludes>
<exclude>application.yaml</exclude>
</excludes>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
18.17.8. Remote Debug a Spring Boot Application Started with Maven
To attach a remote debugger to a Spring Boot application that was started with Maven, you can use the jvmArguments
property of the maven plugin.
See this example for more details.
18.17.9. Build an Executable Archive From Ant without Using spring-boot-antlib
To build with Ant, you need to grab dependencies, compile, and then create a jar or war archive.
To make it executable, you can either use the spring-boot-antlib
module or you can follow these instructions:
-
If you are building a jar, package the application’s classes and resources in a nested
BOOT-INF/classes
directory. If you are building a war, package the application’s classes in a nestedWEB-INF/classes
directory as usual. -
Add the runtime dependencies in a nested
BOOT-INF/lib
directory for a jar orWEB-INF/lib
for a war. Remember not to compress the entries in the archive. -
Add the
provided
(embedded container) dependencies in a nestedBOOT-INF/lib
directory for a jar orWEB-INF/lib-provided
for a war. Remember not to compress the entries in the archive. -
Add the
spring-boot-loader
classes at the root of the archive (so that theMain-Class
is available). -
Use the appropriate launcher (such as
JarLauncher
for a jar file) as aMain-Class
attribute in the manifest and specify the other properties it needs as manifest entries — principally, by setting aStart-Class
property.
The following example shows how to build an executable archive with Ant:
<target name="build" depends="compile">
<jar destfile="target/${ant.project.name}-${spring-boot.version}.jar" compress="false">
<mappedresources>
<fileset dir="target/classes" />
<globmapper from="*" to="BOOT-INF/classes/*"/>
</mappedresources>
<mappedresources>
<fileset dir="src/main/resources" erroronmissingdir="false"/>
<globmapper from="*" to="BOOT-INF/classes/*"/>
</mappedresources>
<mappedresources>
<fileset dir="${lib.dir}/runtime" />
<globmapper from="*" to="BOOT-INF/lib/*"/>
</mappedresources>
<zipfileset src="${lib.dir}/loader/spring-boot-loader-jar-${spring-boot.version}.jar" />
<manifest>
<attribute name="Main-Class" value="org.springframework.boot.loader.launch.JarLauncher" />
<attribute name="Start-Class" value="${start-class}" />
</manifest>
</jar>
</target>
18.18. Ahead-of-time processing
A number of questions often arise when people use the ahead-of-time processing of Spring Boot applications. This section addresses those questions.
18.18.1. Conditions
Ahead-of-time processing optimizes the application and evaluates conditions based on the environment at build time. Profiles are implemented through conditions and are therefore affected, too.
If you want beans that are created based on a condition in an ahead-of-time optimized application, you have to set up the environment when building the application. The beans which are created while ahead-of-time processing at build time are then always created when running the application and can’t be switched off. To do this, you can set the profiles which should be used when building the application.
For Maven, this works by setting the profiles
configuration of the spring-boot-maven-plugin:process-aot
execution:
<profile>
<id>native</id>
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<executions>
<execution>
<id>process-aot</id>
<configuration>
<profiles>profile-a,profile-b</profiles>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</pluginManagement>
</build>
</profile>
For Gradle, you need to configure the ProcessAot
task:
tasks.withType(org.springframework.boot.gradle.tasks.aot.ProcessAot).configureEach {
args('--spring.profiles.active=profile-a,profile-b')
}
Profiles which only change configuration properties that don’t influence conditions are supported without limitations when running ahead-of-time optimized applications.
18.19. Traditional Deployment
Spring Boot supports traditional deployment as well as more modern forms of deployment. This section answers common questions about traditional deployment.
18.19.1. Create a Deployable War File
Because Spring WebFlux does not strictly depend on the servlet API and applications are deployed by default on an embedded Reactor Netty server, War deployment is not supported for WebFlux applications. |
The first step in producing a deployable war file is to provide a SpringBootServletInitializer
subclass and override its configure
method.
Doing so makes use of Spring Framework’s servlet 3.0 support and lets you configure your application when it is launched by the servlet container.
Typically, you should update your application’s main class to extend SpringBootServletInitializer
, as shown in the following example:
@SpringBootApplication
public class MyApplication extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(MyApplication.class);
}
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
}
@SpringBootApplication
class MyApplication : SpringBootServletInitializer() {
override fun configure(application: SpringApplicationBuilder): SpringApplicationBuilder {
return application.sources(MyApplication::class.java)
}
}
fun main(args: Array<String>) {
runApplication<MyApplication>(*args)
}
The next step is to update your build configuration such that your project produces a war file rather than a jar file.
If you use Maven and spring-boot-starter-parent
(which configures Maven’s war plugin for you), all you need to do is to modify pom.xml
to change the packaging to war, as follows:
<packaging>war</packaging>
If you use Gradle, you need to modify build.gradle
to apply the war plugin to the project, as follows:
apply plugin: 'war'
The final step in the process is to ensure that the embedded servlet container does not interfere with the servlet container to which the war file is deployed. To do so, you need to mark the embedded servlet container dependency as being provided.
If you use Maven, the following example marks the servlet container (Tomcat, in this case) as being provided:
<dependencies>
<!-- ... -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
<!-- ... -->
</dependencies>
If you use Gradle, the following example marks the servlet container (Tomcat, in this case) as being provided:
dependencies {
// ...
providedRuntime 'org.springframework.boot:spring-boot-starter-tomcat'
// ...
}
providedRuntime is preferred to Gradle’s compileOnly configuration.
Among other limitations, compileOnly dependencies are not on the test classpath, so any web-based integration tests fail.
|
If you use the Spring Boot build tools, marking the embedded servlet container dependency as provided produces an executable war file with the provided dependencies packaged in a lib-provided
directory.
This means that, in addition to being deployable to a servlet container, you can also run your application by using java -jar
on the command line.
18.19.2. Convert an Existing Application to Spring Boot
To convert an existing non-web Spring application to a Spring Boot application, replace the code that creates your ApplicationContext
and replace it with calls to SpringApplication
or SpringApplicationBuilder
.
Spring MVC web applications are generally amenable to first creating a deployable war application and then migrating it later to an executable war or jar.
See the Getting Started Guide on Converting a jar to a war.
To create a deployable war by extending SpringBootServletInitializer
(for example, in a class called Application
) and adding the Spring Boot @SpringBootApplication
annotation, use code similar to that shown in the following example:
@SpringBootApplication
public class MyApplication extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
// Customize the application or call application.sources(...) to add sources
// Since our example is itself a @Configuration class (through
// @SpringBootApplication)
// we actually do not need to override this method.
return application;
}
}
@SpringBootApplication
class MyApplication : SpringBootServletInitializer() {
override fun configure(application: SpringApplicationBuilder): SpringApplicationBuilder {
// Customize the application or call application.sources(...) to add sources
// Since our example is itself a @Configuration class (through @SpringBootApplication)
// we actually do not need to override this method.
return application
}
}
Remember that, whatever you put in the sources
is merely a Spring ApplicationContext
.
Normally, anything that already works should work here.
There might be some beans you can remove later and let Spring Boot provide its own defaults for them, but it should be possible to get something working before you need to do that.
Static resources can be moved to /public
(or /static
or /resources
or /META-INF/resources
) in the classpath root.
The same applies to messages.properties
(which Spring Boot automatically detects in the root of the classpath).
Vanilla usage of Spring DispatcherServlet
and Spring Security should require no further changes.
If you have other features in your application (for instance, using other servlets or filters), you may need to add some configuration to your Application
context, by replacing those elements from the web.xml
, as follows:
-
A
@Bean
of typeServlet
orServletRegistrationBean
installs that bean in the container as if it were a<servlet/>
and<servlet-mapping/>
inweb.xml
. -
A
@Bean
of typeFilter
orFilterRegistrationBean
behaves similarly (as a<filter/>
and<filter-mapping/>
). -
An
ApplicationContext
in an XML file can be added through an@ImportResource
in yourApplication
. Alternatively, cases where annotation configuration is heavily used already can be recreated in a few lines as@Bean
definitions.
Once the war file is working, you can make it executable by adding a main
method to your Application
, as shown in the following example:
public static void main(String[] args) {
SpringApplication.run(MyApplication.class, args);
}
fun main(args: Array<String>) {
runApplication<MyApplication>(*args)
}
If you intend to start your application as a war or as an executable application, you need to share the customizations of the builder in a method that is both available to the Java
Kotlin
|
Applications can fall into more than one category:
-
Servlet 3.0+ applications with no
web.xml
. -
Applications with a
web.xml
. -
Applications with a context hierarchy.
-
Applications without a context hierarchy.
All of these should be amenable to translation, but each might require slightly different techniques.
Servlet 3.0+ applications might translate pretty easily if they already use the Spring Servlet 3.0+ initializer support classes.
Normally, all the code from an existing WebApplicationInitializer
can be moved into a SpringBootServletInitializer
.
If your existing application has more than one ApplicationContext
(for example, if it uses AbstractDispatcherServletInitializer
) then you might be able to combine all your context sources into a single SpringApplication
.
The main complication you might encounter is if combining does not work and you need to maintain the context hierarchy.
See the entry on building a hierarchy for examples.
An existing parent context that contains web-specific features usually needs to be broken up so that all the ServletContextAware
components are in the child context.
Applications that are not already Spring applications might be convertible to Spring Boot applications, and the previously mentioned guidance may help.
However, you may yet encounter problems.
In that case, we suggest asking questions on Stack Overflow with a tag of spring-boot
.
18.19.3. Deploying a WAR to WebLogic
To deploy a Spring Boot application to WebLogic, you must ensure that your servlet initializer directly implements WebApplicationInitializer
(even if you extend from a base class that already implements it).
A typical initializer for WebLogic should resemble the following example:
@SpringBootApplication
public class MyApplication extends SpringBootServletInitializer implements WebApplicationInitializer {
}
@SpringBootApplication
class MyApplication : SpringBootServletInitializer(), WebApplicationInitializer
If you use Logback, you also need to tell WebLogic to prefer the packaged version rather than the version that was pre-installed with the server.
You can do so by adding a WEB-INF/weblogic.xml
file with the following contents:
<?xml version="1.0" encoding="UTF-8"?>
<wls:weblogic-web-app
xmlns:wls="http://xmlns.oracle.com/weblogic/weblogic-web-app"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
https://java.sun.com/xml/ns/javaee/ejb-jar_3_0.xsd
http://xmlns.oracle.com/weblogic/weblogic-web-app
https://xmlns.oracle.com/weblogic/weblogic-web-app/1.4/weblogic-web-app.xsd">
<wls:container-descriptor>
<wls:prefer-application-packages>
<wls:package-name>org.slf4j</wls:package-name>
</wls:prefer-application-packages>
</wls:container-descriptor>
</wls:weblogic-web-app>
18.20. Docker Compose
This section includes topics relating to the Docker Compose support in Spring Boot.
18.20.1. Customizing the JDBC URL
When using JdbcConnectionDetails
with Docker Compose, the parameters of the JDBC URL
can be customized by applying the org.springframework.boot.jdbc.parameters
label to the
service. For example:
services:
postgres:
image: 'postgres:15.3'
environment:
- 'POSTGRES_USER=myuser'
- 'POSTGRES_PASSWORD=secret'
- 'POSTGRES_DB=mydb'
ports:
- '5432:5432'
labels:
org.springframework.boot.jdbc.parameters: 'ssl=true&sslmode=require'
With this Docker Compose file in place, the JDBC URL used is jdbc:postgresql://127.0.0.1:5432/mydb?ssl=true&sslmode=require
.
18.20.2. Sharing services between multiple applications
If you want to share services between multiple applications, create the compose.yaml
file in one of the applications and then use the configuration property spring.docker.compose.file
in the other applications to reference the compose.yaml
file.
You should also set spring.docker.compose.lifecycle-management
to start-only
, as it defaults to start-and-stop
and stopping one application would shut down the shared services for the other still running applications, too.
Setting it to start-only
won’t stop the shared services on application stop, but a caveat is that if you shut down all applications, the services stay running.
You can stop the services manually by running docker compose stop
on the command line in the directory which contains the compose.yaml
file.
Appendices
Appendix A: Common Application Properties
Various properties can be specified inside your application.properties
file, inside your application.yaml
file, or as command line switches.
This appendix provides a list of common Spring Boot properties and references to the underlying classes that consume them.
Spring Boot provides various conversion mechanism with advanced value formatting, make sure to review the properties conversion section. |
Property contributions can come from additional jar files on your classpath, so you should not consider this an exhaustive list. Also, you can define your own properties. |
.A.1. Core Properties
Name | Description | Default Value |
---|---|---|
Enable debug logs. |
|
|
Arbitrary properties to add to the info endpoint. |
||
Charset to use for console output. |
||
Charset to use for file output. |
||
Location of the logging configuration file. For instance, `classpath:logback.xml` for Logback. |
||
Conversion word used when logging exceptions. |
|
|
Log file name (for instance, `myapp.log`). Names can be an exact location or relative to the current directory. |
||
Location of the log file. For instance, `/var/log`. |
||
Log groups to quickly change multiple loggers at the same time. For instance, `logging.group.db=org.hibernate,org.springframework.jdbc`. |
||
Whether to include the application name in the logs. |
|
|
Log levels severity mapping. For instance, `logging.level.org.springframework=DEBUG`. |
||
Overriding configuration files used to create a composite configuration. |
||
Whether to clean the archive log files on startup. |
|
|
Pattern for rolled-over log file names. |
|
|
Maximum log file size. |
|
|
Maximum number of archive log files to keep. |
|
|
Total size of log backups to be kept. |
|
|
Appender pattern for output to the console. Supported only with the default Logback setup. |
|
|
Appender pattern for log correlation. Supported only with the default Logback setup. |
||
Appender pattern for log date format. Supported only with the default Logback setup. |
|
|
Appender pattern for output to a file. Supported only with the default Logback setup. |
|
|
Appender pattern for log level. Supported only with the default Logback setup. |
|
|
Register a shutdown hook for the logging system when it is initialized. Disabled automatically when deployed as a war file. |
|
|
Log level threshold for console output. |
|
|
Log level threshold for file output. |
|
|
Add @EnableAspectJAutoProxy. |
|
|
Whether subclass-based (CGLIB) proxies are to be created (true), as opposed to standard Java interface-based proxies (false). |
|
|
Whether to enable admin features for the application. |
|
|
JMX name of the application admin MBean. |
|
|
Application name. |
||
Auto-configuration classes to exclude. |
||
Banner file encoding. |
|
|
Banner text resource location. |
|
|
Whether to skip search of BeanInfo classes. |
|
|
Whether to log form data at DEBUG level, and headers at TRACE level. |
|
|
Limit on the number of bytes that can be buffered whenever the input stream needs to be aggregated. This applies only to the auto-configured WebFlux server and WebClient instances. By default this is not set, in which case individual codec defaults apply. Most codecs are limited to 256K by default. |
||
Required cloud platform for the document to be included. |
||
Profile expressions that should match for the document to be included. |
||
Config file locations used in addition to the defaults. |
||
Import additional config data. |
||
Config file locations that replace the defaults. |
||
Config file name. |
|
|
File encoding. |
|
|
Location of the generated build-info.properties file. |
|
|
File encoding. |
|
|
Location of the generated git.properties file. |
|
|
JMX domain name. |
||
Expose management beans to the JMX domain. |
|
|
JMX Registration policy. |
|
|
MBeanServer bean name. |
|
|
Whether unique runtime object names should be ensured. |
|
|
Timeout for the shutdown of any phase (group of SmartLifecycle beans with the same 'phase' value). |
|
|
Whether bean definition overriding, by registering a definition with the same name as an existing definition, is allowed. |
|
|
Whether to allow circular references between beans and automatically try to resolve them. |
|
|
Mode used to display the banner when the application runs. |
|
|
Override the Cloud Platform auto-detection. |
||
Whether to keep the application alive even if there are no more non-daemon threads. |
|
|
Whether initialization should be performed lazily. |
|
|
Whether to log information about the application when it starts. |
|
|
Whether the application should have a shutdown hook registered. |
|
|
Sources (class names, package names, or XML resource locations) to include in the ApplicationContext. |
||
Flag to explicitly request a specific type of web application. If not set, auto-detected based on the classpath. |
||
Expected character encoding the application must use. |
||
Whether to always apply the MessageFormat rules, parsing even messages without arguments. |
|
|
Comma-separated list of basenames (essentially a fully-qualified classpath location), each following the ResourceBundle convention with relaxed support for slash based locations. If it doesn't contain a package qualifier (such as "org.mypackage"), it will be resolved from the classpath root. |
|
|
Loaded resource bundle files cache duration. When not set, bundles are cached forever. If a duration suffix is not specified, seconds will be used. |
||
Message bundles encoding. |
|
|
Whether to fall back to the system Locale if no files for a specific Locale have been found. if this is turned off, the only fallback will be the default file (e.g. "messages.properties" for basename "messages"). |
|
|
Whether to use the message code as the default message instead of throwing a "NoSuchMessageException". Recommended during development only. |
|
|
Configures the ANSI output. |
|
|
Fails if ApplicationPidFileWriter is used but it cannot write the PID file. |
||
Location of the PID file to write (if ApplicationPidFileWriter is used). |
||
Comma-separated list of active profiles. Can be overridden by a command line switch. |
||
Name of the profile to enable if no profile is active. |
|
|
Profile groups to define a logical name for a related group of profiles. |
||
Unconditionally activate the specified comma-separated list of profiles (or list of profiles if using YAML). |
||
Whether to automatically start the scheduler after initialization. |
|
|
Prefixes for single-line comments in SQL initialization scripts. |
|
|
Database schema initialization mode. |
|
|
Platform to use in initialization scripts if the @@platform@@ placeholder is used. Auto-detected by default. |
||
Path to the SQL file to use to initialize the database schema. |
|
|
Quartz job store type. |
|
|
Whether configured jobs should overwrite existing job definitions. |
|
|
Additional Quartz Scheduler properties. |
||
Name of the scheduler. |
|
|
Delay after which the scheduler is started once initialization completes. Setting this property makes sense if no jobs should be run before the entire application has started up. |
|
|
Whether to wait for running jobs to complete on shutdown. |
|
|
Context Propagation support mode for Reactor operators. |
|
|
Whether the Reactor Debug Agent should be enabled when reactor-tools is present. |
|
|
Amount of time to wait before shutting down resources. |
||
Java keystore SSL trust material. |
||
PEM-encoded SSL trust material. |
||
Quiet period, after which changes are detected. |
|
|
Whether core threads are allowed to time out. This enables dynamic growing and shrinking of the pool. |
|
|
Core number of threads. |
|
|
Time limit for which threads may remain idle before being terminated. |
|
|
Maximum allowed number of threads. If tasks are filling up the queue, the pool can expand up to that size to accommodate the load. Ignored if the queue is unbounded. |
||
Queue capacity. An unbounded capacity does not increase the pool and therefore ignores the "max-size" property. |
||
Whether the executor should wait for scheduled tasks to complete on shutdown. |
|
|
Maximum time the executor should wait for remaining tasks to complete. |
||
Set the maximum number of parallel accesses allowed. -1 indicates no concurrency limit at all. |
||
Prefix to use for the names of newly created threads. |
|
|
Maximum allowed number of threads. |
|
|
Whether the executor should wait for scheduled tasks to complete on shutdown. |
|
|
Maximum time the executor should wait for remaining tasks to complete. |
||
Set the maximum number of parallel accesses allowed. -1 indicates no concurrency limit at all. |
||
Prefix to use for the names of newly created threads. |
|
|
Whether to use virtual threads. |
|
|
Enable trace logs. |
|
.A.2. Cache Properties
Name | Description | Default Value |
---|---|---|
Comma-separated list of cache names to create if supported by the underlying cache manager. Usually, this disables the ability to create additional caches on-the-fly. |
||
The spec to use to create caches. See CaffeineSpec for more details on the spec format. |
||
Entry expiration. By default the entries never expire. Note that this value is ultimately converted to seconds. |
||
The location of the configuration file to use to initialize Infinispan. |
||
The location of the configuration file to use to initialize the cache manager. The configuration file is dependent of the underlying cache implementation. |
||
Fully qualified name of the CachingProvider implementation to use to retrieve the JSR-107 compliant cache manager. Needed only if more than one JSR-107 implementation is available on the classpath. |
||
Allow caching null values. |
|
|
Whether to enable cache statistics. |
|
|
Key prefix. |
||
Entry expiration. By default the entries never expire. |
||
Whether to use the key prefix when writing to Redis. |
|
|
Cache type. By default, auto-detected according to the environment. |
.A.3. Mail Properties
Name | Description | Default Value |
---|---|---|
Default MimeMessage encoding. |
|
|
SMTP server host. For instance, 'smtp.example.com'. |
||
Session JNDI name. When set, takes precedence over other Session settings. |
||
Login password of the SMTP server. |
||
SMTP server port. |
||
Additional JavaMail Session properties. |
||
Protocol used by the SMTP server. |
|
|
Whether to test that the mail server is available on startup. |
|
|
Login user of the SMTP server. |
||
SendGrid API key. |
||
SendGrid proxy host. |
||
SendGrid proxy port. |
.A.4. JSON Properties
Name | Description | Default Value |
---|---|---|
Format to use when serializing Date objects. |
||
Whether to disable the escaping of HTML characters such as '<', '>', etc. |
||
Whether to exclude inner classes during serialization. |
||
Whether to enable serialization of complex map keys (i.e. non-primitives). |
||
Whether to exclude all fields from consideration for serialization or deserialization that do not have the "Expose" annotation. |
||
Naming policy that should be applied to an object's field during serialization and deserialization. |
||
Whether to generate non-executable JSON by prefixing the output with some special text. |
||
Whether to be lenient about parsing JSON that doesn't conform to RFC 4627. |
||
Serialization policy for Long and long types. |
||
Whether to output serialized JSON that fits in a page for pretty printing. |
||
Whether to serialize null fields. |
||
Strategy to use to auto-detect constructor, and in particular behavior with single-argument constructors. |
|
|
Jackson on/off features for enums. |
||
Jackson on/off features for JsonNodes. |
||
Date format string or a fully-qualified date format class name. For instance, 'yyyy-MM-dd HH:mm:ss'. |
||
Global default setting (if any) for leniency. |
||
Controls the inclusion of properties during serialization. Configured with one of the values in Jackson's JsonInclude.Include enumeration. |
||
Jackson on/off features that affect the way Java objects are deserialized. |
||
Jackson on/off features for generators. |
||
Locale used for formatting. |
||
Jackson general purpose on/off features. |
||
Jackson on/off features for parsers. |
||
One of the constants on Jackson's PropertyNamingStrategies. Can also be a fully-qualified class name of a PropertyNamingStrategy implementation. |
||
Jackson on/off features that affect the way Java objects are serialized. |
||
Time zone used when formatting dates. For instance, "America/Los_Angeles" or "GMT+10". |
||
Jackson visibility thresholds that can be used to limit which methods (and fields) are auto-detected. |
.A.5. Data Properties
Name | Description | Default Value |
---|---|---|
Compression supported by the Cassandra binary protocol. |
|
|
Location of the configuration file to use. |
||
Timeout to use when establishing driver connections. |
|
|
Timeout to use for internal queries that run as part of the initialization process, just after a connection is opened. |
|
|
Cluster node addresses in the form 'host:port', or a simple 'host' to use the configured port. |
|
|
Timeout to use for control queries. |
|
|
Keyspace name to use. |
||
Datacenter that is considered "local". Contact points should be from this datacenter. |
||
Login password of the server. |
||
Heartbeat interval after which a message is sent on an idle connection to make sure it's still alive. |
|
|
Idle timeout before an idle connection is removed. |
|
|
Port to use if a contact point does not specify one. |
|
|
Queries consistency level. |
||
How many rows will be retrieved simultaneously in a single network round-trip. |
|
|
Queries serial consistency level. |
||
How often the throttler attempts to dequeue requests. Set this high enough that each attempt will process multiple entries in the queue, but not delay requests too much. |
||
Maximum number of requests that are allowed to execute in parallel. |
||
Maximum number of requests that can be enqueued when the throttling threshold is exceeded. |
||
Maximum allowed request rate. |
||
Request throttling type. |
|
|
How long the driver waits for a request to complete. |
|
|
Schema action to take at startup. |
|
|
Name of the Cassandra session. |
||
SSL bundle name. |
||
Whether to enable SSL support. |
||
Login user of the server. |
||
Connection string used to locate the Couchbase cluster. |
||
Length of time an HTTP connection may remain idle before it is closed and removed from the pool. |
|
|
Maximum number of sockets per node. |
|
|
Minimum number of sockets per node. |
|
|
SSL bundle name. |
||
Whether to enable SSL support. Enabled automatically if a "keyStore" or "bundle" is provided unless specified otherwise. |
||
Timeout for the analytics service. |
|
|
Bucket connect timeout. |
|
|
Bucket disconnect timeout. |
|
|
Timeout for operations on a specific key-value. |
|
|
Timeout for operations on a specific key-value with a durability level. |
|
|
Timeout for the management operations. |
|
|
N1QL query operations timeout. |
|
|
Timeout for the search service. |
|
|
Regular and geospatial view operations timeout. |
|
|
Cluster password. |
||
Cluster username. |
||
Whether to enable the PersistenceExceptionTranslationPostProcessor. |
|
|
Type of Cassandra repositories to enable. |
|
|
Automatically create views and indexes. Use the meta-data provided by "@ViewIndexed", "@N1qlPrimaryIndexed" and "@N1qlSecondaryIndexed". |
|
|
Name of the bucket to connect to. |
||
Fully qualified name of the FieldNamingStrategy to use. |
||
Type of Couchbase repositories to enable. |
|
|
Name of the scope used for all collection access. |
||
Name of the field that stores the type information for complex types when using "MappingCouchbaseConverter". |
|
|
Whether to enable Elasticsearch repositories. |
|
|
Whether to enable JDBC repositories. |
|
|
Bootstrap mode for JPA repositories. |
|
|
Whether to enable JPA repositories. |
|
|
Whether to enable LDAP repositories. |
|
|
Additional server hosts. Cannot be set with URI or if 'host' is not specified. Additional hosts will use the default mongo port of 27017. If you want to use a different port you can use the "host:port" syntax. |
||
Authentication database name. |
||
Whether to enable auto-index creation. |
||
Database name. Overrides database in URI. |
||
Fully qualified name of the FieldNamingStrategy to use. |
||
GridFS bucket name. |
||
GridFS database name. |
||
Mongo server host. Cannot be set with URI. |
||
Login password of the mongo server. Cannot be set with URI. |
||
Mongo server port. Cannot be set with URI. |
||
Required replica set name for the cluster. Cannot be set with URI. |
||
Type of Mongo repositories to enable. |
|
|
SSL bundle name. |
||
Whether to enable SSL support. Enabled automatically if "bundle" is provided unless specified otherwise. |
||
Mongo database URI. Overrides host, port, username, and password. |
|
|
Login user of the mongo server. Cannot be set with URI. |
||
Representation to use when converting a UUID to a BSON binary value. |
|
|
Database name to use. By default, the server decides the default database to use. |
||
Type of Neo4j repositories to enable. |
|
|
Whether to enable R2DBC repositories. |
|
|
Client name to be set on connections with CLIENT SETNAME. |
||
Type of client to use. By default, auto-detected according to the classpath. |
||
Maximum number of redirects to follow when executing commands across the cluster. |
||
Comma-separated list of "host:port" pairs to bootstrap from. This represents an "initial" list of cluster nodes and is required to have at least one entry. |
||
Connection timeout. |
||
Database index used by the connection factory. |
|
|
Redis server host. |
|
|
Whether to enable the pool. Enabled automatically if "commons-pool2" is available. With Jedis, pooling is implicitly enabled in sentinel mode and this setting only applies to single node setup. |
||
Maximum number of connections that can be allocated by the pool at a given time. Use a negative value for no limit. |
|
|
Maximum number of "idle" connections in the pool. Use a negative value to indicate an unlimited number of idle connections. |
|
|
Maximum amount of time a connection allocation should block before throwing an exception when the pool is exhausted. Use a negative value to block indefinitely. |
|
|
Target for the minimum number of idle connections to maintain in the pool. This setting only has an effect if both it and time between eviction runs are positive. |
|
|
Time between runs of the idle object evictor thread. When positive, the idle object evictor thread starts, otherwise no idle object eviction is performed. |
||
Whether adaptive topology refreshing using all available refresh triggers should be used. |
|
|
|
Whether to discover and query all cluster nodes for obtaining the cluster topology. When set to false, only the initial seed nodes are used as sources for topology discovery. |
|
Cluster topology refresh period. |
||
Whether to enable the pool. Enabled automatically if "commons-pool2" is available. With Jedis, pooling is implicitly enabled in sentinel mode and this setting only applies to single node setup. |
||
Maximum number of connections that can be allocated by the pool at a given time. Use a negative value for no limit. |
|
|
Maximum number of "idle" connections in the pool. Use a negative value to indicate an unlimited number of idle connections. |
|
|
Maximum amount of time a connection allocation should block before throwing an exception when the pool is exhausted. Use a negative value to block indefinitely. |
|
|
Target for the minimum number of idle connections to maintain in the pool. This setting only has an effect if both it and time between eviction runs are positive. |
|
|
Time between runs of the idle object evictor thread. When positive, the idle object evictor thread starts, otherwise no idle object eviction is performed. |
||
Shutdown timeout. |
|
|
Login password of the redis server. |
||
Redis server port. |
|
|
Whether to enable Redis repositories. |
|
|
Name of the Redis server. |
||
Comma-separated list of "host:port" pairs. |
||
Password for authenticating with sentinel(s). |
||
Login username for authenticating with sentinel(s). |
||
SSL bundle name. |
||
Whether to enable SSL support. Enabled automatically if "bundle" is provided unless specified otherwise. |
||
Read timeout. |
||
Connection URL. Overrides host, port, username, and password. Example: redis://user:[email protected]:6379 |
||
Login username of the redis server. |
||
Base path to be used by Spring Data REST to expose repository resources. |
||
Content type to use as a default when none is specified. |
||
Default size of pages. |
||
Strategy to use to determine which repositories get exposed. |
|
|
Whether to enable enum value translation through the Spring Data REST default resource bundle. |
||
Name of the URL query string parameter that indicates how many results to return at once. |
||
Maximum size of pages. |
||
Name of the URL query string parameter that indicates what page to return. |
||
Whether to return a response body after creating an entity. |
||
Whether to return a response body after updating an entity. |
||
Name of the URL query string parameter that indicates what direction to sort results. |
||
Default page size. |
|
|
Maximum page size to be accepted. |
|
|
Whether to expose and assume 1-based page number indexes. Defaults to "false", meaning a page number of 0 in the request equals the first page. |
|
|
Page index parameter name. |
|
|
General prefix to be prepended to the page number and page size parameters. |
||
Delimiter to be used between the qualifier and the actual page number and size properties. |
|
|
Page size parameter name. |
|
|
Sort parameter name. |
|
|
|
Commons DBCP2 specific settings bound to an instance of DBCP2's BasicDataSource |
|
Fully qualified name of the JDBC driver. Auto-detected based on the URL by default. |
||
Connection details for an embedded database. Defaults to the most suitable embedded database that is available on the classpath. |
||
Whether to generate a random datasource name. |
|
|
|
Hikari specific settings bound to an instance of Hikari's HikariDataSource |
|
JNDI location of the datasource. Class, url, username and password are ignored when set. |
||
Datasource name to use if "generate-unique-name" is false. Defaults to "testdb" when using an embedded database, otherwise null. |
||
|
Oracle UCP specific settings bound to an instance of Oracle UCP's PoolDataSource |
|
Login password of the database. |
||
|
Tomcat datasource specific settings bound to an instance of Tomcat JDBC's DataSource |
|
Fully qualified name of the connection pool implementation to use. By default, it is auto-detected from the classpath. |
||
JDBC URL of the database. |
||
Login username of the database. |
||
XA datasource fully qualified name. |
||
Properties to pass to the XA data source. |
||
Connection timeout used when communicating with Elasticsearch. |
|
|
Password for authentication with Elasticsearch. |
||
Prefix added to the path of every request sent to Elasticsearch. |
||
Delay of a sniff execution scheduled after a failure. |
|
|
Interval between consecutive ordinary sniff executions. |
|
|
SSL bundle name. |
||
Whether to enable socket keep alive between client and Elasticsearch. |
|
|
Socket timeout used when communicating with Elasticsearch. |
|
|
Comma-separated list of the Elasticsearch instances to use. |
|
|
Username for authentication with Elasticsearch. |
||
Whether to enable the console. |
|
|
Path at which the console is available. |
|
|
Whether to enable trace output. |
|
|
Password to access preferences and tools of H2 Console. |
||
Whether to enable remote access. |
|
|
Number of rows that should be fetched from the database when more rows are needed. Use -1 to use the JDBC driver's default configuration. |
|
|
Maximum number of rows. Use -1 to use the JDBC driver's default configuration. |
|
|
Query timeout. Default is to use the JDBC driver's default configuration. If a duration suffix is not specified, seconds will be used. |
||
SQL dialect to use. Auto-detected by default. |
||
Target database to operate on, auto-detected by default. Can be alternatively set using the "databasePlatform" property. |
||
Name of the target database to operate on, auto-detected by default. Can be alternatively set using the "Database" enum. |
||
Whether to defer DataSource initialization until after any EntityManagerFactory beans have been created and initialized. |
|
|
Whether to initialize the schema on startup. |
|
|
DDL mode. This is actually a shortcut for the "hibernate.hbm2ddl.auto" property. Defaults to "create-drop" when using an embedded database and no schema manager was detected. Otherwise, defaults to "none". |
||
Fully qualified name of the implicit naming strategy. |
||
Fully qualified name of the physical naming strategy. |
||
Mapping resources (equivalent to "mapping-file" entries in persistence.xml). |
||
Register OpenEntityManagerInViewInterceptor. Binds a JPA EntityManager to the thread for the entire processing of the request. |
|
|
Additional native properties to set on the JPA provider. |
||
Whether to enable logging of SQL statements. |
|
|
Whether read-only operations should use an anonymous environment. Disabled by default unless a username is set. |
||
Base suffix from which all operations should originate. |
||
LDAP specification settings. |
||
List of base DNs. |
||
Embedded LDAP password. |
||
Embedded LDAP username. |
||
Schema (LDIF) script resource reference. |
|
|
Embedded LDAP port. |
|
|
Whether to enable LDAP schema validation. |
|
|
Path to the custom schema. |
||
Login password of the server. |
||
Whether NameNotFoundException should be ignored in searches through the LdapTemplate. |
|
|
Whether PartialResultException should be ignored in searches through the LdapTemplate. |
|
|
Whether SizeLimitExceededException should be ignored in searches through the LdapTemplate. |
|
|
LDAP URLs of the server. |
||
Login username of the server. |
||
Kerberos ticket for connecting to the database. Mutual exclusive with a given username. |
||
Login password of the server. |
||
Realm to connect to. |
||
Login user of the server. |
||
Timeout for borrowing connections from the pool. |
|
|
Maximum time transactions are allowed to retry. |
|
|
Acquisition of new connections will be attempted for at most configured timeout. |
|
|
Pooled connections that have been idle in the pool for longer than this threshold will be tested before they are used again. |
||
Whether to log leaked sessions. |
|
|
Pooled connections older than this threshold will be closed and removed from the pool. |
|
|
Maximum amount of connections in the connection pool towards a single database. |
|
|
Whether to enable metrics. |
|
|
Path to the file that holds the trusted certificates. |
||
Whether the driver should use encrypted traffic. |
|
|
Whether hostname verification is required. |
|
|
Trust strategy to use. |
|
|
URI used by the driver. |
|
|
Whether to generate a random database name. Ignore any configured name when enabled. |
|
|
Database name. Set if no name is specified in the url. Default to "testdb" when using an embedded database. |
||
Login password of the database. Set if no password is specified in the url. |
||
Whether pooling is enabled. Requires r2dbc-pool. |
|
|
Initial connection pool size. |
|
|
Maximum time to acquire a connection from the pool. By default, wait indefinitely. |
||
Maximum time to wait to create a new connection. By default, wait indefinitely. |
||
Maximum amount of time that a connection is allowed to sit idle in the pool. |
|
|
Maximum lifetime of a connection in the pool. By default, connections have an infinite lifetime. |
||
Maximal connection pool size. |
|
|
Maximum time to validate a connection from the pool. By default, wait indefinitely. |
||
Minimal number of idle connections. |
|
|
Validation depth. |
|
|
Validation query. |
||
Additional R2DBC options. |
||
R2DBC URL of the database. database name, username, password and pooling options specified in the url take precedence over individual options. |
||
Login username of the database. Set if no username is specified in the url. |
.A.6. Transaction Properties
Name | Description | Default Value |
---|---|---|
Whether to enable JTA support. |
|
|
Default transaction timeout. If a duration suffix is not specified, seconds will be used. |
||
Whether to roll back on commit failures. |
.A.7. Data Migration Properties
Name | Description | Default Value |
---|---|---|
Description to tag an existing schema with when applying a baseline. |
|
|
Whether to automatically call baseline when migrating a non-empty schema. |
|
|
Version to tag an existing schema with when executing baseline. |
|
|
Whether to batch SQL statements when executing them. Requires Flyway Teams. |
||
Migrations that Flyway should consider when migrating or undoing. When empty all available migrations are considered. Requires Flyway Teams. |
||
Whether to disable cleaning of the database. |
|
|
Whether to automatically call clean when a validation error occurs. |
|
|
Maximum number of retries when attempting to connect to the database. |
|
|
Maximum time between retries when attempting to connect to the database. If a duration suffix is not specified, seconds will be used. |
|
|
Whether Flyway should attempt to create the schemas specified in the schemas property. |
|
|
Default schema name managed by Flyway (case-sensitive). |
||
Whether to attempt to automatically detect SQL migration file encoding. Requires Flyway Teams. |
||
Fully qualified name of the JDBC driver. Auto-detected based on the URL by default. |
||
Whether to enable flyway. |
|
|
Encoding of SQL migrations. |
|
|
Rules for the built-in error handling to override specific SQL states and error codes. Requires Flyway Teams. |
||
Whether Flyway should execute SQL within a transaction. |
|
|
Whether to fail if a location of migration scripts doesn't exist. |
|
|
Whether to group all pending migrations together in the same transaction when applying them. |
|
|
Ignore migrations that match this comma-separated list of patterns when validating migrations. Requires Flyway Teams. |
||
SQL statements to execute to initialize a connection immediately after obtaining it. |
||
Username recorded in the schema history table as having applied the migration. |
||
Properties to pass to the JDBC driver. Requires Flyway Teams. |
||
Path of the Kerberos config file. Requires Flyway Teams. |
||
Licence key for Flyway Teams. |
||
Locations of migrations scripts. Can contain the special "{vendor}" placeholder to use vendor-specific locations. |
|
|
Maximum number of retries when trying to obtain a lock. |
|
|
Loggers Flyway should use. |
|
|
Whether to allow mixing transactional and non-transactional statements within the same migration. |
|
|
Path of the Oracle Kerberos cache file. Requires Flyway Teams. |
||
Whether to enable support for Oracle SQL*Plus commands. Requires Flyway Teams. |
||
Whether to issue a warning rather than an error when a not-yet-supported Oracle SQL*Plus statement is encountered. Requires Flyway Teams. |
||
Location of the Oracle Wallet, used to sign in to the database automatically. Requires Flyway Teams. |
||
Whether to allow migrations to be run out of order. |
|
|
Whether Flyway should output a table with the results of queries when executing migrations. Requires Flyway Teams. |
||
Login password of the database to migrate. |
||
Prefix of placeholders in migration scripts. |
|
|
Perform placeholder replacement in migration scripts. |
|
|
Separator of default placeholders. |
|
|
Suffix of placeholders in migration scripts. |
|
|
Placeholders and their replacements to apply to sql migration scripts. |
||
Whether transactional advisory locks should be used. If set to false, session-level locks are used instead. |
||
File name prefix for repeatable SQL migrations. |
|
|
Scheme names managed by Flyway (case-sensitive). |
||
Prefix of placeholders in migration scripts. |
|
|
Suffix of placeholders in migration scripts. |
|
|
Whether to skip default callbacks. If true, only custom callbacks are used. |
|
|
Whether to skip default resolvers. If true, only custom resolvers are used. |
|
|
Whether Flyway should skip executing the contents of the migrations and only update the schema history table. Requires Flyway teams. |
||
File name prefix for SQL migrations. |
|
|
File name separator for SQL migrations. |
|
|
File name suffix for SQL migrations. |
|
|
Path to the SQL Server Kerberos login file. Requires Flyway Teams. |
||
Whether to stream SQL migrations when executing them. Requires Flyway Teams. |
||
Name of the schema history table that will be used by Flyway. |
|
|
Tablespace in which the schema history table is created. Ignored when using a database that does not support tablespaces. Defaults to the default tablespace of the connection used by Flyway. |
||
Target version up to which migrations should be considered. |
|
|
JDBC url of the database to migrate. If not set, the primary configured data source is used. |
||
Login user of the database to migrate. |
||
Whether to validate migrations and callbacks whose scripts do not obey the correct naming convention. |
|
|
Whether to automatically call validate when performing a migration. |
|
|
Change log configuration path. |
|
|
Whether to clear all checksums in the current changelog, so they will be recalculated upon the next update. |
|
|
Comma-separated list of runtime contexts to use. |
||
Name of table to use for tracking concurrent Liquibase usage. |
|
|
Name of table to use for tracking change history. |
|
|
Default database schema. |
||
Fully qualified name of the JDBC driver. Auto-detected based on the URL by default. |
||
Whether to first drop the database schema. |
|
|
Whether to enable Liquibase support. |
|
|
Comma-separated list of runtime labels to use. |
||
Schema to use for Liquibase objects. |
||
Tablespace to use for Liquibase objects. |
||
Change log parameters. |
||
Login password of the database to migrate. |
||
File to which rollback SQL is written when an update is performed. |
||
Whether to print a summary of the update operation. Values can be 'off', 'summary' (default), 'verbose' |
||
Where to print a summary of the update operation. Values can be 'log' (default), 'console', or 'all'. |
||
Tag name to use when applying database changes. Can also be used with "rollbackFile" to generate a rollback script for all existing changes associated with that tag. |
||
Whether rollback should be tested before update is performed. |
|
|
JDBC URL of the database to migrate. If not set, the primary configured data source is used. |
||
Login user of the database to migrate. |
||
Whether initialization should continue when an error occurs. |
|
|
Locations of the data (DML) scripts to apply to the database. |
||
Encoding of the schema and data scripts. |
||
Mode to apply when determining whether initialization should be performed. |
|
|
Password of the database to use when applying initialization scripts (if different). |
||
Platform to use in the default schema or data script locations, schema-${platform}.sql and data-${platform}.sql. |
|
|
Locations of the schema (DDL) scripts to apply to the database. |
||
Statement separator in the schema and data scripts. |
|
|
Username of the database to use when applying initialization scripts (if different). |
.A.8. Integration Properties
Name | Description | Default Value |
---|---|---|
URL of the ActiveMQ broker. Auto-generated by default. |
||
Time to wait before considering a close complete. |
|
|
Whether to stop message delivery before re-delivering messages from a rolled back transaction. This implies that message order is not preserved when this is enabled. |
|
|
Whether to trust all packages. |
||
Comma-separated list of specific packages to trust (when not trusting all packages). |
||
Login password of the broker. |
||
Whether to block when a connection is requested and the pool is full. Set it to false to throw a "JMSException" instead. |
|
|
Blocking period before throwing an exception if the pool is still full. |
|
|
Whether a JmsPoolConnectionFactory should be created, instead of a regular ConnectionFactory. |
|
|
Connection idle timeout. |
|
|
Maximum number of pooled connections. |
|
|
Maximum number of pooled sessions per connection in the pool. |
|
|
Time to sleep between runs of the idle connection eviction thread. When negative, no idle connection eviction thread runs. |
|
|
Whether to use only one anonymous "MessageProducer" instance. Set it to false to create one "MessageProducer" every time one is required. |
|
|
Time to wait on message sends for a response. Set it to 0 to wait forever. |
|
|
Login user of the broker. |
||
Artemis broker url. |
|
|
Cluster password. Randomly generated on startup by default. |
||
Journal file directory. Not necessary if persistence is turned off. |
||
Whether to enable embedded mode if the Artemis server APIs are available. |
|
|
Whether to enable persistent store. |
|
|
Comma-separated list of queues to create on startup. |
|
|
Server ID. By default, an auto-incremented counter is used. |
|
|
Comma-separated list of topics to create on startup. |
|
|
Artemis deployment mode, auto-detected by default. |
||
Login password of the broker. |
||
Whether to block when a connection is requested and the pool is full. Set it to false to throw a "JMSException" instead. |
|
|
Blocking period before throwing an exception if the pool is still full. |
|
|
Whether a JmsPoolConnectionFactory should be created, instead of a regular ConnectionFactory. |
|
|
Connection idle timeout. |
|
|
Maximum number of pooled connections. |
|
|
Maximum number of pooled sessions per connection in the pool. |
|
|
Time to sleep between runs of the idle connection eviction thread. When negative, no idle connection eviction thread runs. |
|
|
Whether to use only one anonymous "MessageProducer" instance. Set it to false to create one "MessageProducer" every time one is required. |
|
|
Login user of the broker. |
||
Database schema initialization mode. |
|
|
Transaction isolation level to use when creating job meta-data for new jobs. |
||
Platform to use in initialization scripts if the @@platform@@ placeholder is used. Auto-detected by default. |
||
Path to the SQL file to use to initialize the database schema. |
|
|
Table prefix for all the batch meta-data tables. |
||
Execute all Spring Batch jobs in the context on startup. |
|
|
Job name to execute on startup. Must be specified if multiple Jobs are found in the context. |
||
The location of the configuration file to use to initialize Hazelcast. |
||
Whether to create input channels if necessary. |
|
|
Default number of subscribers allowed on, for example, a 'PublishSubscribeChannel'. |
||
Default number of subscribers allowed on, for example, a 'DirectChannel'. |
||
A comma-separated list of endpoint bean names patterns that should not be started automatically during application startup. |
||
A comma-separated list of message header names that should not be populated into Message instances during a header copying operation. |
||
Whether to throw an exception when a reply is not expected anymore by a gateway. |
|
|
Whether to ignore failures for one or more of the handlers of the global 'errorChannel'. |
|
|
Whether to not silently ignore messages on the global 'errorChannel' when there are no subscribers. |
|
|
Database schema initialization mode. |
|
|
Platform to use in initialization scripts if the @@platform@@ placeholder is used. Auto-detected by default. |
||
Path to the SQL file to use to initialize the database schema. |
|
|
Whether Spring Integration components should perform logging in the main message flow. When disabled, such logging will be skipped without checking the logging level. When enabled, such logging is controlled as normal by the logging system's log level configuration. |
|
|
Comma-separated list of simple patterns to match against the names of Spring Integration components. When matched, observation instrumentation will be performed for the component. Please refer to the javadoc of the smartMatch method of Spring Integration's PatternMatchUtils for details of the pattern syntax. |
||
Cron expression for polling. Mutually exclusive with 'fixedDelay' and 'fixedRate'. |
||
Polling delay period. Mutually exclusive with 'cron' and 'fixedRate'. |
||
Polling rate period. Mutually exclusive with 'fixedDelay' and 'cron'. |
||
Polling initial delay. Applied for 'fixedDelay' and 'fixedRate'; ignored for 'cron'. |
||
Maximum number of messages to poll per polling cycle. |
||
How long to wait for messages on poll. |
|
|
TCP RSocket server host to connect to. |
||
TCP RSocket server port to connect to. |
||
WebSocket RSocket server uri to connect to. |
||
Whether to handle message mapping for RSocket through Spring Integration. |
|
|
Whether to cache message consumers. |
|
|
Whether to cache sessions. |
|
|
Whether to cache message producers. |
|
|
Size of the session cache (per JMS Session type). |
|
|
Connection factory JNDI name. When set, takes precedence to others connection factory auto-configurations. |
||
Start the container automatically on startup. |
|
|
Maximum number of concurrent consumers. |
||
Minimum number of concurrent consumers. When max-concurrency is not specified the minimum will also be used as the maximum. |
||
Timeout to use for receive calls. Use -1 for a no-wait receive or 0 for no timeout at all. The latter is only feasible if not running within a transaction manager and is generally discouraged since it prevents clean shutdown. |
|
|
Acknowledge mode of the listener container. |
|
|
Whether the listener container should use transacted JMS sessions. Defaults to false in the presence of a JtaTransactionManager and true otherwise. |
||
Whether the default destination type is topic. |
|
|
Default destination to use on send and receive operations that do not have a destination parameter. |
||
Delivery delay to use for send calls. |
||
Delivery mode. Enables QoS (Quality of Service) when set. |
||
Priority of a message when sending. Enables QoS (Quality of Service) when set. |
||
Whether to enable explicit QoS (Quality of Service) when sending a message. When enabled, the delivery mode, priority and time-to-live properties will be used when sending a message. QoS is automatically enabled when at least one of those settings is customized. |
||
Timeout to use for receive calls. |
||
Acknowledge mode used when creating sessions. |
|
|
Whether to use transacted sessions. |
|
|
Time-to-live of a message when sending. Enables QoS (Quality of Service) when set. |
||
Whether to automatically create topics during context initialization. When set to false, disables automatic topic creation during context initialization. |
|
|
ID to pass to the server when making requests. Used for server-side logging. |
||
Close timeout. |
||
Whether to fail fast if the broker is not available on startup. |
|
|
Whether to enable modification of existing topic configuration. |
|
|
Operation timeout. |
||
Additional admin-specific properties used to configure the client. |
||
Security protocol used to communicate with brokers. |
||
Name of the SSL bundle to use. |
||
Password of the private key in either key store key or key store file. |
||
Certificate chain in PEM format with a list of X.509 certificates. |
||
Private key in PEM format with PKCS#8 keys. |
||
Location of the key store file. |
||
Store password for the key store file. |
||
Type of the key store. |
||
SSL protocol to use. |
||
Trusted certificates in PEM format with X.509 certificates. |
||
Location of the trust store file. |
||
Store password for the trust store file. |
||
Type of the trust store. |
||
Comma-delimited list of host:port pairs to use for establishing the initial connections to the Kafka cluster. Applies to all components unless overridden. |
||
ID to pass to the server when making requests. Used for server-side logging. |
||
Frequency with which the consumer offsets are auto-committed to Kafka if 'enable.auto.commit' is set to true. |
||
What to do when there is no initial offset in Kafka or if the current offset no longer exists on the server. |
||
Comma-delimited list of host:port pairs to use for establishing the initial connections to the Kafka cluster. Overrides the global property, for consumers. |
||
ID to pass to the server when making requests. Used for server-side logging. |
||
Whether the consumer's offset is periodically committed in the background. |
||
Maximum amount of time the server blocks before answering the fetch request if there isn't sufficient data to immediately satisfy the requirement given by "fetch-min-size". |
||
Minimum amount of data the server should return for a fetch request. |
||
Unique string that identifies the consumer group to which this consumer belongs. |
||
Expected time between heartbeats to the consumer coordinator. |
||
Isolation level for reading messages that have been written transactionally. |
|
|
Deserializer class for keys. |
||
Maximum number of records returned in a single call to poll(). |
||
Additional consumer-specific properties used to configure the client. |
||
Security protocol used to communicate with brokers. |
||
Name of the SSL bundle to use. |
||
Password of the private key in either key store key or key store file. |
||
Certificate chain in PEM format with a list of X.509 certificates. |
||
Private key in PEM format with PKCS#8 keys. |
||
Location of the key store file. |
||
Store password for the key store file. |
||
Type of the key store. |
||
SSL protocol to use. |
||
Trusted certificates in PEM format with X.509 certificates. |
||
Location of the trust store file. |
||
Store password for the trust store file. |
||
Type of the trust store. |
||
Deserializer class for values. |
||
Control flag for login configuration. |
|
|
Whether to enable JAAS configuration. |
|
|
Login module. |
|
|
Additional JAAS options. |
||
Number of records between offset commits when ackMode is "COUNT" or "COUNT_TIME". |
||
Listener AckMode. See the spring-kafka documentation. |
||
Time between offset commits when ackMode is "TIME" or "COUNT_TIME". |
||
Support for asynchronous record acknowledgements. Only applies when spring.kafka.listener.ack-mode is manual or manual-immediate. |
||
Whether to auto start the container. |
|
|
Whether to instruct the container to change the consumer thread name during initialization. |
||
Prefix for the listener's consumer client.id property. |
||
Number of threads to run in the listener containers. |
||
Sleep interval between Consumer.poll(Duration) calls. |
|
|
Time between publishing idle consumer events (no data received). |
||
Time between publishing idle partition consumer events (no data received for partition). |
||
Whether the container stops after the current record is processed or after all the records from the previous poll are processed. |
|
|
Whether to log the container configuration during initialization (INFO level). |
||
Whether the container should fail to start if at least one of the configured topics are not present on the broker. |
|
|
Time between checks for non-responsive consumers. If a duration suffix is not specified, seconds will be used. |
||
Multiplier applied to "pollTimeout" to determine if a consumer is non-responsive. |
||
Whether to enable observation. |
|
|
Timeout to use when polling the consumer. |
||
Listener type. |
|
|
Number of acknowledgments the producer requires the leader to have received before considering a request complete. |
||
Default batch size. A small batch size will make batching less common and may reduce throughput (a batch size of zero disables batching entirely). |
||
Comma-delimited list of host:port pairs to use for establishing the initial connections to the Kafka cluster. Overrides the global property, for producers. |
||
Total memory size the producer can use to buffer records waiting to be sent to the server. |
||
ID to pass to the server when making requests. Used for server-side logging. |
||
Compression type for all data generated by the producer. |
||
Serializer class for keys. |
||
Additional producer-specific properties used to configure the client. |
||
When greater than zero, enables retrying of failed sends. |
||
Security protocol used to communicate with brokers. |
||
Name of the SSL bundle to use. |
||
Password of the private key in either key store key or key store file. |
||
Certificate chain in PEM format with a list of X.509 certificates. |
||
Private key in PEM format with PKCS#8 keys. |
||
Location of the key store file. |
||
Store password for the key store file. |
||
Type of the key store. |
||
SSL protocol to use. |
||
Trusted certificates in PEM format with X.509 certificates. |
||
Location of the trust store file. |
||
Store password for the trust store file. |
||
Type of the trust store. |
||
When non empty, enables transaction support for producer. |
||
Serializer class for values. |
||
Additional properties, common to producers and consumers, used to configure the client. |
||
Total number of processing attempts made before sending the message to the DLT. |
|
|
Canonical backoff period. Used as an initial value in the exponential case, and as a minimum value in the uniform case. |
|
|
Whether to enable topic-based non-blocking retries. |
|
|
Maximum wait between retries. If less than the delay then the default of 30 seconds is applied. |
|
|
Multiplier to use for generating the next backoff delay. |
|
|
Whether to have the backoff delays. |
|
|
Security protocol used to communicate with brokers. |
||
Name of the SSL bundle to use. |
||
Password of the private key in either key store key or key store file. |
||
Certificate chain in PEM format with a list of X.509 certificates. |
||
Private key in PEM format with PKCS#8 keys. |
||
Location of the key store file. |
||
Store password for the key store file. |
||
Type of the key store. |
||
SSL protocol to use. |
||
Trusted certificates in PEM format with X.509 certificates. |
||
Location of the trust store file. |
||
Store password for the trust store file. |
||
Type of the trust store. |
||
Kafka streams application.id property; default spring.application.name. |
||
Whether to auto-start the streams factory bean. |
|
|
Comma-delimited list of host:port pairs to use for establishing the initial connections to the Kafka cluster. Overrides the global property, for streams. |
||
Cleanup the application’s local state directory on shutdown. |
|
|
Cleanup the application’s local state directory on startup. |
|
|
ID to pass to the server when making requests. Used for server-side logging. |
||
Additional Kafka properties used to configure the streams. |
||
The replication factor for change log topics and repartition topics created by the stream processing application. |
||
Security protocol used to communicate with brokers. |
||
Name of the SSL bundle to use. |
||
Password of the private key in either key store key or key store file. |
||
Certificate chain in PEM format with a list of X.509 certificates. |
||
Private key in PEM format with PKCS#8 keys. |
||
Location of the key store file. |
||
Store password for the key store file. |
||
Type of the key store. |
||
SSL protocol to use. |
||
Trusted certificates in PEM format with X.509 certificates. |
||
Location of the trust store file. |
||
Store password for the trust store file. |
||
Type of the trust store. |
||
Directory location for the state store. |
||
Maximum size of the in-memory state store cache across all threads. |
||
Default topic to which messages are sent. |
||
Whether to enable observation. |
|
|
Transaction id prefix, override the transaction id prefix in the producer factory. |
||
Authentication parameter(s) as a map of parameter names to parameter values. |
||
Fully qualified class name of the authentication plugin. |
||
Duration to wait for a connection to server to be established. |
|
|
Server response read time out for any request. |
|
|
Server request time out for any request. |
|
|
Pulsar web URL for the admin endpoint in the format '(http|https)://host:port'. |
|
|
Authentication parameter(s) as a map of parameter names to parameter values. |
||
Fully qualified class name of the authentication plugin. |
||
Duration to wait for a connection to a broker to be established. |
|
|
Client lookup timeout. |
||
Client operation timeout. |
|
|
Pulsar service URL in the format '(pulsar|pulsar+ssl)://host:port'. |
|
|
Name of the dead topic where the failing messages will be sent. |
||
|
Name of the initial subscription of the dead letter topic. When not set, the initial subscription will not be created. However, when the property is set then the broker's 'allowAutoSubscriptionCreation' must be enabled or the DLQ producer will fail. |
|
|
Maximum number of times that a message will be redelivered before being sent to the dead letter queue. |
|
|
Name of the retry topic where the failing messages will be sent. |
|
Consumer name to identify a particular consumer from the topic stats. |
||
Priority level for shared subscription consumers. |
|
|
Whether to read messages from the compacted topic rather than the full message backlog. |
|
|
Whether to auto retry messages. |
|
|
Position where to initialize a newly created subscription. |
||
Subscription mode to be used when subscribing to the topic. |
||
Subscription name for the consumer. |
||
Determines which type of topics (persistent, non-persistent, or all) the consumer should be subscribed to when using pattern subscriptions. |
||
Subscription type to be used when subscribing to a topic. |
||
Topics the consumer subscribes to. |
||
Pattern for topics the consumer subscribes to. |
||
List of mappings from message type to topic name and schema info to use as a defaults when a topic name and/or schema is not explicitly specified when producing or consuming messages of the mapped type. |
||
Whether to enable function support. |
|
|
Whether to stop processing further function creates/updates when a failure occurs. |
|
|
Whether to throw an exception if any failure is encountered during server startup while creating/updating functions. |
|
|
Whether to throw an exception if any failure is encountered during server shutdown while enforcing stop policy on functions. |
|
|
Whether to record observations for when the Observations API is available and the client supports it. |
|
|
SchemaType of the consumed messages. |
||
Type of access to the topic the producer requires. |
||
Whether to automatically batch messages. |
|
|
Whether to enable caching in the PulsarProducerFactory. |
|
|
Time period to expire unused entries in the cache. |
|
|
Initial size of cache. |
|
|
Maximum size of cache (entries). |
|
|
Whether to split large-size messages into multiple chunks. |
|
|
Message compression type. |
||
Message hashing scheme to choose the partition to which the message is published. |
||
Message routing mode for a partitioned producer. |
||
Name for the producer. If not assigned, a unique name is generated. |
||
Time before a message has to be acknowledged by the broker. |
|
|
Topic the producer will publish to. |
||
Reader name. |
||
Whether to read messages from a compacted topic rather than a full message backlog of a topic. |
|
|
Subscription name. |
||
Prefix of subscription role. |
||
Topis the reader subscribes to. |
||
Whether to record observations for when the Observations API is available. |
|
|
Mode used to shuffle configured addresses. |
|
|
Comma-separated list of addresses to which the client should connect. When set, the host and port are ignored. |
||
Duration to wait to obtain a channel if the cache size has been reached. If 0, always create a new channel. |
||
Number of channels to retain in the cache. When "check-timeout" > 0, max channels per connection. |
||
Connection factory cache mode. |
|
|
Number of connections to cache. Only applies when mode is CONNECTION. |
||
Continuation timeout for RPC calls in channels. Set it to zero to wait forever. |
|
|
Connection timeout. Set it to zero to wait forever. |
||
Whether to create an AmqpAdmin bean. |
|
|
RabbitMQ host. Ignored if an address is set. |
|
|
Acknowledge mode of container. |
||
Whether to start the container automatically on startup. |
|
|
Number of consumers per queue. |
||
Whether the container should present batched messages as discrete messages or call the listener with the batch. |
|
|
Whether rejected deliveries are re-queued by default. |
||
Whether the container (when stopped) should stop immediately after processing the current message or stop after processing all pre-fetched messages. |
|
|
How often idle container events should be published. |
||
Whether to fail if the queues declared by the container are not available on the broker. |
|
|
Maximum number of unacknowledged messages that can be outstanding at each consumer. |
||
Whether publishing retries are enabled. |
|
|
Duration between the first and second attempt to deliver a message. |
|
|
Maximum number of attempts to deliver a message. |
|
|
Maximum duration between attempts. |
|
|
Multiplier to apply to the previous retry interval. |
|
|
Whether retries are stateless or stateful. |
|
|
Acknowledge mode of container. |
||
Whether to start the container automatically on startup. |
|
|
Batch size, expressed as the number of physical messages, to be used by the container. |
||
Minimum number of listener invoker threads. |
||
Whether the container creates a batch of messages based on the 'receive-timeout' and 'batch-size'. Coerces 'de-batching-enabled' to true to include the contents of a producer created batch in the batch as discrete records. |
|
|
Whether the container should present batched messages as discrete messages or call the listener with the batch. |
|
|
Whether rejected deliveries are re-queued by default. |
||
Whether the container (when stopped) should stop immediately after processing the current message or stop after processing all pre-fetched messages. |
|
|
How often idle container events should be published. |
||
Maximum number of listener invoker threads. |
||
Whether to fail if the queues declared by the container are not available on the broker and/or whether to stop the container if one or more queues are deleted at runtime. |
|
|
Maximum number of unacknowledged messages that can be outstanding at each consumer. |
||
Whether publishing retries are enabled. |
|
|
Duration between the first and second attempt to deliver a message. |
|
|
Maximum number of attempts to deliver a message. |
|
|
Maximum duration between attempts. |
|
|
Multiplier to apply to the previous retry interval. |
|
|
Whether retries are stateless or stateful. |
|
|
Whether to start the container automatically on startup. |
|
|
Whether the container will support listeners that consume native stream messages instead of Spring AMQP messages. |
|
|
Listener container type. |
|
|
Maximum size of the body of inbound (received) messages. |
|
|
Login to authenticate against the broker. |
|
|
RabbitMQ port. Ignored if an address is set. Default to 5672, or 5671 if SSL is enabled. |
||
Type of publisher confirms to use. |
||
Whether to enable publisher returns. |
|
|
Number of channels per connection requested by the client. Use 0 for unlimited. |
|
|
Requested heartbeat timeout; zero for none. If a duration suffix is not specified, seconds will be used. |
||
SSL algorithm to use. By default, configured by the Rabbit client library. |
||
SSL bundle name. |
||
Whether to enable SSL support. Determined automatically if an address is provided with the protocol (amqp:// vs. amqps://). |
||
Path to the key store that holds the SSL certificate. |
||
Key store algorithm. |
|
|
Password used to access the key store. |
||
Key store type. |
|
|
Trust store that holds SSL certificates. |
||
Trust store algorithm. |
|
|
Password used to access the trust store. |
||
Trust store type. |
|
|
Whether to enable server side certificate validation. |
|
|
Whether to enable hostname verification. |
|
|
Host of a RabbitMQ instance with the Stream plugin enabled. |
|
|
Name of the stream. |
||
Login password to authenticate to the broker. When not set spring.rabbitmq.password is used. |
||
Stream port of a RabbitMQ instance with the Stream plugin enabled. |
||
Login user to authenticate to the broker. When not set, spring.rabbitmq.username is used. |
||
Virtual host of a RabbitMQ instance with the Stream plugin enabled. When not set, spring.rabbitmq.virtual-host is used. |
||
Name of the default queue to receive messages from when none is specified explicitly. |
||
Name of the default exchange to use for send operations. |
||
Whether to enable mandatory messages. |
||
Timeout for receive() operations. |
||
Timeout for sendAndReceive() operations. |
||
Whether publishing retries are enabled. |
|
|
Duration between the first and second attempt to deliver a message. |
|
|
Maximum number of attempts to deliver a message. |
|
|
Maximum duration between attempts. |
|
|
Multiplier to apply to the previous retry interval. |
|
|
Value of a default routing key to use for send operations. |
||
Login user to authenticate to the broker. |
|
|
Virtual host to use when connecting to the broker. |
||
Path that serves as the base URI for the services. |
|
|
Servlet init parameters to pass to Spring Web Services. |
||
Load on startup priority of the Spring Web Services servlet. |
|
|
Comma-separated list of locations of WSDLs and accompanying XSDs to be exposed as beans. |
.A.9. Web Properties
Name | Description | Default Value |
---|---|---|
Whether credentials are supported. When not set, credentials are not supported. |
||
Comma-separated list of HTTP headers to allow in a request. '*' allows all headers. |
||
Comma-separated list of HTTP methods to allow. '*' allows all methods. When not set, defaults to GET. |
||
Comma-separated list of origin patterns to allow. Unlike allowed origins which only support '*', origin patterns are more flexible, e.g. 'https://*.example.com', and can be used with allow-credentials. When neither allowed origins nor allowed origin patterns are set, cross-origin requests are effectively disabled. |
||
Comma-separated list of origins to allow with '*' allowing all origins. When allow-credentials is enabled, '*' cannot be used, and setting origin patterns should be considered instead. When neither allowed origins nor allowed origin patterns are set, cross-origin requests are effectively disabled. |
||
Comma-separated list of headers to include in a response. |
||
How long the response from a pre-flight request can be cached by clients. If a duration suffix is not specified, seconds will be used. |
|
|
Whether the default GraphiQL UI is enabled. |
|
|
Path to the GraphiQL UI endpoint. |
|
|
Path at which to expose a GraphQL request HTTP endpoint. |
|
|
Mapping of the RSocket message handler. |
||
File extensions for GraphQL schema files. |
|
|
Whether schema should be compared to the application to detect missing mappings. |
|
|
Whether field introspection should be enabled at the schema level. |
|
|
Locations of GraphQL schema files. |
|
|
Whether the endpoint that prints the schema is enabled. Schema is available under spring.graphql.path + "/schema". |
|
|
Time within which the initial {@code CONNECTION_INIT} type message must be received. |
|
|
Path of the GraphQL WebSocket subscription endpoint. |
||
Whether application/hal+json responses should be sent to requests that accept application/json. |
|
|
Path that serves as the base URI for the application. If specified, overrides the value of "@ApplicationPath". |
||
Jersey filter chain order. |
|
|
Init parameters to pass to Jersey through the servlet or filter. |
||
Load on startup priority of the Jersey servlet. |
|
|
Jersey integration type. |
|
|
Amount of time before asynchronous request handling times out. If this value is not set, the default timeout of the underlying implementation is used. |
||
Whether a request parameter ("format" by default) should be used to determine the requested media type. |
|
|
Map file extensions to media types for content negotiation. For instance, yml to text/yaml. |
||
Query parameter name to use when "favor-parameter" is enabled. |
||
Preferred JSON mapper to use for HTTP message conversion. By default, auto-detected according to the environment. |
||
Whether to dispatch OPTIONS requests to the FrameworkServlet doService method. |
|
|
Whether to dispatch TRACE requests to the FrameworkServlet doService method. |
|
|
Date format to use, for example 'dd/MM/yyyy'. |
||
Date-time format to use, for example 'yyyy-MM-dd HH:mm:ss'. |
||
Time format to use, for example 'HH:mm:ss'. |
||
Whether to enable Spring's FormContentFilter. |
|
|
Whether to enable Spring's HiddenHttpMethodFilter. |
|
|
Whether logging of (potentially sensitive) request details at DEBUG and TRACE level is allowed. |
|
|
Whether to enable warn logging of exceptions resolved by a "HandlerExceptionResolver", except for "DefaultHandlerExceptionResolver". |
|
|
Formatting strategy for message codes. For instance, 'PREFIX_ERROR_CODE'. |
||
Choice of strategy for matching request paths against registered mappings. |
|
|
Whether RFC 7807 Problem Details support should be enabled. |
|
|
Whether to publish a ServletRequestHandledEvent at the end of each request. |
|
|
Load on startup priority of the dispatcher servlet. |
|
|
Path of the dispatcher servlet. Setting a custom value for this property is not compatible with the PathPatternParser matching strategy. |
|
|
Path pattern used for static resources. |
|
|
Spring MVC view prefix. |
||
Spring MVC view suffix. |
||
Path pattern used for WebJar assets. |
|
|
Level of leak detection for reference-counted buffers. If not configured via 'ResourceLeakDetector.setLevel' or the 'io.netty.leakDetection.level' system property, default to 'simple'. |
||
Whether to enable support of multipart uploads. |
|
|
Threshold after which files are written to disk. |
|
|
Intermediate location of uploaded files. |
||
Max file size. |
|
|
Max request size. |
|
|
Whether to resolve the multipart request lazily at the time of file or parameter access. |
|
|
Whether to resolve the multipart request strictly complying with the Servlet specification, only to be used for "multipart/form-data" requests. |
|
|
Sessions flush mode. Determines when session changes are written to the session store. |
|
|
Name of the map used to store sessions. |
|
|
Sessions save mode. Determines how session changes are tracked and saved to the session store. |
|
|
Cron expression for expired session cleanup job. |
|
|
Sessions flush mode. Determines when session changes are written to the session store. |
|
|
Database schema initialization mode. |
|
|
Platform to use in initialization scripts if the @@platform@@ placeholder is used. Auto-detected by default. |
||
Sessions save mode. Determines how session changes are tracked and saved to the session store. |
|
|
Path to the SQL file to use to initialize the database schema. |
|
|
Name of the database table used to store sessions. |
|
|
Collection name used to store sessions. |
|
|
Cron expression for expired session cleanup job. Only supported when repository-type is set to indexed. |
|
|
The configure action to apply when no user defined ConfigureRedisAction bean is present. |
|
|
Sessions flush mode. Determines when session changes are written to the session store. |
|
|
Namespace for keys used to store sessions. |
|
|
Type of Redis session repository to configure. |
|
|
Sessions save mode. Determines how session changes are tracked and saved to the session store. |
|
|
Session repository filter dispatcher types. |
|
|
Session repository filter order. |
||
Session timeout. If a duration suffix is not specified, seconds will be used. |
||
Locale to use. By default, this locale is overridden by the "Accept-Language" header. |
||
Define how the locale should be resolved. |
|
|
Whether to enable default resource handling. |
|
|
Indicate that the response message is intended for a single user and must not be stored by a shared cache. |
||
Indicate that any cache may store the response. |
||
Maximum time the response should be cached, in seconds if no duration suffix is not specified. |
||
Indicate that once it has become stale, a cache must not use the response without re-validating it with the server. |
||
Indicate that the cached response can be reused only if re-validated with the server. |
||
Indicate to not cache the response in any case. |
||
Indicate intermediaries (caches and others) that they should not transform the response content. |
||
Same meaning as the "must-revalidate" directive, except that it does not apply to private caches. |
||
Maximum time the response should be cached by shared caches, in seconds if no duration suffix is not specified. |
||
Maximum time the response may be used when errors are encountered, in seconds if no duration suffix is not specified. |
||
|
Maximum time the response can be served after it becomes stale, in seconds if no duration suffix is not specified. |
|
Cache period for the resources served by the resource handler. If a duration suffix is not specified, seconds will be used. Can be overridden by the 'spring.web.resources.cache.cachecontrol' properties. |
||
Whether we should use the "lastModified" metadata of the files in HTTP caching headers. |
|
|
Whether to enable caching in the Resource chain. |
|
|
Whether to enable resolution of already compressed resources (gzip, brotli). Checks for a resource name with the '.gz' or '.br' file extensions. |
|
|
Whether to enable the Spring Resource Handling chain. By default, disabled unless at least one strategy has been enabled. |
||
Whether to enable the content Version Strategy. |
|
|
Comma-separated list of patterns to apply to the content Version Strategy. |
|
|
Whether to enable the fixed Version Strategy. |
|
|
Comma-separated list of patterns to apply to the fixed Version Strategy. |
|
|
Version string to use for the fixed Version Strategy. |
||
Locations of static resources. Defaults to classpath:[/META-INF/resources/, /resources/, /static/, /public/]. |
|
|
Base path for all web handlers. |
||
Date format to use, for example 'dd/MM/yyyy'. |
||
Date-time format to use, for example 'yyyy-MM-dd HH:mm:ss'. |
||
Time format to use, for example 'HH:mm:ss'. |
||
Whether to enable Spring's HiddenHttpMethodFilter. |
|
|
Directory used to store file parts larger than 'maxInMemorySize'. Default is a directory named 'spring-multipart' created under the system temporary directory. Ignored when using the PartEvent streaming support. |
||
Character set used to decode headers. |
|
|
Maximum amount of disk space allowed per part. Default is -1 which enforces no limits. |
|
|
Maximum amount of memory allowed per headers section of each part. Set to -1 to enforce no limits. |
|
|
Maximum amount of memory allowed per part before it's written to disk. Set to -1 to store all contents in memory. |
|
|
Maximum number of parts allowed in a given multipart request. Default is -1 which enforces no limits. |
|
|
Whether RFC 7807 Problem Details support should be enabled. |
|
|
Path pattern used for static resources. |
|
|
Path pattern used for WebJar assets. |
|
.A.10. Templating Properties
Name | Description | Default Value |
---|---|---|
Whether HttpServletRequest attributes are allowed to override (hide) controller generated model attributes of the same name. |
|
|
Whether HttpSession attributes are allowed to override (hide) controller generated model attributes of the same name. |
|
|
Whether to enable template caching. |
|
|
Template encoding. |
|
|
Whether to check that the templates location exists. |
|
|
Content-Type value. |
|
|
Whether to enable MVC view resolution for this technology. |
|
|
Whether all request attributes should be added to the model prior to merging with the template. |
|
|
Whether all HttpSession attributes should be added to the model prior to merging with the template. |
|
|
Whether to expose a RequestContext for use by Spring's macro library, under the name "springMacroRequestContext". |
|
|
Whether to prefer file system access for template loading to enable hot detection of template changes. When a template path is detected as a directory, templates are loaded from the directory only and other matching classpath locations will not be considered. |
|
|
Prefix that gets prepended to view names when building a URL. |
||
Name of the RequestContext attribute for all views. |
||
Well-known FreeMarker keys which are passed to FreeMarker's Configuration. |
||
Suffix that gets appended to view names when building a URL. |
|
|
Comma-separated list of template paths. |
|
|
View names that can be resolved. |
||
Whether HttpServletRequest attributes are allowed to override (hide) controller generated model attributes of the same name. |
|
|
Whether HttpSession attributes are allowed to override (hide) controller generated model attributes of the same name. |
|
|
Whether to enable template caching. |
|
|
Template encoding. |
|
|
Whether to check that the templates location exists. |
|
|
|
See GroovyMarkupConfigurer |
|
Content-Type value. |
|
|
Whether to enable MVC view resolution for this technology. |
|
|
Whether all request attributes should be added to the model prior to merging with the template. |
|
|
Whether all HttpSession attributes should be added to the model prior to merging with the template. |
|
|
Whether to expose a RequestContext for use by Spring's macro library, under the name "springMacroRequestContext". |
|
|
Prefix that gets prepended to view names when building a URL. |
||
Name of the RequestContext attribute for all views. |
||
Template path. |
|
|
Suffix that gets appended to view names when building a URL. |
|
|
View names that can be resolved. |
||
Template encoding. |
|
|
Whether to check that the templates location exists. |
|
|
Whether to enable MVC view resolution for Mustache. |
|
|
Prefix to apply to template names. |
|
|
Media types supported by Mustache views. |
|
|
Name of the RequestContext attribute for all views. |
||
Whether HttpServletRequest attributes are allowed to override (hide) controller generated model attributes of the same name. |
|
|
Whether HttpSession attributes are allowed to override (hide) controller generated model attributes of the same name. |
|
|
Whether to enable template caching. |
|
|
Content-Type value. |
||
Whether all request attributes should be added to the model prior to merging with the template. |
|
|
Whether all HttpSession attributes should be added to the model prior to merging with the template. |
|
|
Whether to expose a RequestContext for use by Spring's macro library, under the name "springMacroRequestContext". |
|
|
Suffix to apply to template names. |
|
|
View names that can be resolved. |
||
Whether to enable template caching. |
|
|
Whether to check that the template exists before rendering it. |
|
|
Whether to check that the templates location exists. |
|
|
Enable the SpringEL compiler in SpringEL expressions. |
|
|
Whether to enable Thymeleaf view resolution for Web frameworks. |
|
|
Template files encoding. |
|
|
Comma-separated list of view names (patterns allowed) that should be excluded from resolution. |
||
Template mode to be applied to templates. See also Thymeleaf's TemplateMode enum. |
|
|
Prefix that gets prepended to view names when building a URL. |
|
|
Comma-separated list of view names (patterns allowed) that should be the only ones executed in CHUNKED mode when a max chunk size is set. |
||
Comma-separated list of view names (patterns allowed) that should be executed in FULL mode even if a max chunk size is set. |
||
Maximum size of data buffers used for writing to the response. Templates will execute in CHUNKED mode by default if this is set. |
|
|
Media types supported by the view technology. |
|
|
Whether hidden form inputs acting as markers for checkboxes should be rendered before the checkbox element itself. |
|
|
Content-Type value written to HTTP responses. |
|
|
|
Whether Thymeleaf should start writing partial output as soon as possible or buffer until template processing is finished. |
|
Suffix that gets appended to view names when building a URL. |
|
|
Order of the template resolver in the chain. By default, the template resolver is first in the chain. Order start at 1 and should only be set if you have defined additional "TemplateResolver" beans. |
||
Comma-separated list of view names (patterns allowed) that can be resolved. |
.A.11. Server Properties
Name | Description | Default Value |
---|---|---|
Network address to which the server should bind. |
||
Whether response compression is enabled. |
|
|
Comma-separated list of user agents for which responses should not be compressed. |
||
Comma-separated list of MIME types that should be compressed. |
|
|
Minimum "Content-Length" value that is required for compression to be performed. |
|
|
When to include "errors" attribute. |
|
|
Include the "exception" attribute. |
|
|
When to include "message" attribute. |
|
|
When to include the "trace" attribute. |
|
|
Path of the error controller. |
|
|
Whether to enable the default error page displayed in browsers in case of a server error. |
|
|
Strategy for handling X-Forwarded-* headers. |
||
Whether to enable HTTP/2 support, if the current environment supports it. |
|
|
Append to log. |
|
|
Custom log format, see org.eclipse.jetty.server.CustomRequestLog. If defined, overrides the "format" configuration key. |
||
Enable access log. |
|
|
Date format to place in log file name. |
||
Log filename. If not specified, logs redirect to "System.err". |
||
Log format. |
|
|
Request paths that should not be logged. |
||
Number of days before rotated log files are deleted. |
|
|
Time that the connection can be idle before it is closed. |
||
Maximum number of connections that the server accepts and processes at any given time. |
|
|
Maximum size of the form content in any HTTP post request. |
|
|
Maximum size of the HTTP response header. |
|
|
Number of acceptor threads to use. When the value is -1, the default, the number of acceptors is derived from the operating environment. |
|
|
Maximum thread idle time. |
|
|
Maximum number of threads. |
|
|
Maximum capacity of the thread pool's backing queue. A default is computed based on the threading configuration. |
||
Minimum number of threads. |
|
|
Number of selector threads to use. When the value is -1, the default, the number of selectors is derived from the operating environment. |
|
|
Maximum size of the HTTP request header. |
|
|
Connection timeout of the Netty channel. |
||
Maximum content length of an H2C upgrade request. |
|
|
Idle timeout of the Netty channel. When not specified, an infinite timeout is used. |
||
Initial buffer size for HTTP request decoding. |
|
|
Maximum length that can be decoded for an HTTP request's initial line. |
|
|
Maximum number of requests that can be made per connection. By default, a connection serves unlimited number of requests. |
||
Whether to validate headers when decoding requests. |
|
|
Server HTTP port. |
|
|
Domain for the cookie. |
||
Whether to use "HttpOnly" cookies for the cookie. |
||
Maximum age of the cookie. If a duration suffix is not specified, seconds will be used. A positive value indicates when the cookie expires relative to the current time. A value of 0 means the cookie should expire immediately. A negative value means no "Max-Age". |
||
Name for the cookie. |
||
Path of the cookie. |
||
SameSite setting for the cookie. |
||
Whether to always mark the cookie as secure. |
||
Session timeout. If a duration suffix is not specified, seconds will be used. |
|
|
Value to use for the Server response header (if empty, no header is sent). |
||
Display name of the application. |
|
|
Servlet context init parameters. |
||
Context path of the application. |
||
Charset of HTTP requests and responses. Added to the "Content-Type" header if not set explicitly. |
|
|
Whether to enable http encoding support. |
|
|
Whether to force the encoding to the configured charset on HTTP requests and responses. |
||
Whether to force the encoding to the configured charset on HTTP requests. Defaults to true when "force" has not been specified. |
||
Whether to force the encoding to the configured charset on HTTP responses. |
||
Mapping of locale to charset for response encoding. |
||
Class name of the servlet to use for JSPs. If registered is true and this class * is on the classpath then it will be registered. |
|
|
Init parameters used to configure the JSP servlet. |
||
Whether the JSP servlet is registered. |
|
|
Whether to register the default Servlet with the container. |
|
|
Domain for the cookie. |
||
Whether to use "HttpOnly" cookies for the cookie. |
||
Maximum age of the cookie. If a duration suffix is not specified, seconds will be used. A positive value indicates when the cookie expires relative to the current time. A value of 0 means the cookie should expire immediately. A negative value means no "Max-Age". |
||
Name of the cookie. |
||
Path of the cookie. |
||
SameSite setting for the cookie. |
||
Whether to always mark the cookie as secure. |
||
Whether to persist session data between restarts. |
|
|
Directory used to store session data. |
||
Session timeout. If a duration suffix is not specified, seconds will be used. |
|
|
Session tracking modes. |
||
Type of shutdown that the server will support. |
|
|
The name of a configured SSL bundle. |
||
Path to a PEM-encoded SSL certificate file. |
||
Path to a PEM-encoded private key file for the SSL certificate. |
||
Supported SSL ciphers. |
||
Client authentication mode. Requires a trust store. |
||
Whether to enable SSL support. |
|
|
Enabled SSL protocols. |
||
Alias that identifies the key in the key store. |
||
Password used to access the key in the key store. |
||
Path to the key store that holds the SSL certificate (typically a jks file). |
||
Password used to access the key store. |
||
Provider for the key store. |
||
Type of the key store. |
||
SSL protocol to use. |
|
|
Path to a PEM-encoded SSL certificate authority file. |
||
Path to a PEM-encoded private key file for the SSL certificate authority. |
||
Trust store that holds SSL certificates. |
||
Password used to access the trust store. |
||
Provider for the trust store. |
||
Type of the trust store. |
||
Maximum queue length for incoming connection requests when all possible request processing threads are in use. |
|
|
Whether to buffer output such that it is flushed only periodically. |
|
|
Whether to check for log file existence so it can be recreated if an external process has renamed it. |
|
|
Whether logging of the request will only be enabled if "ServletRequest.getAttribute(conditionIf)" does not yield null. |
||
Whether logging of the request will only be enabled if "ServletRequest.getAttribute(conditionUnless)" yield null. |
||
Directory in which log files are created. Can be absolute or relative to the Tomcat base dir. |
|
|
Enable access log. |
|
|
Character set used by the log file. Default to the system default character set. |
||
Date format to place in the log file name. |
|
|
Whether to use IPv6 canonical representation format as defined by RFC 5952. |
|
|
Locale used to format timestamps in log entries and in log file name suffix. Default to the default locale of the Java process. |
||
Number of days to retain the access log files before they are removed. |
|
|
Format pattern for access logs. |
|
|
Log file name prefix. |
|
|
Whether to defer inclusion of the date stamp in the file name until rotate time. |
|
|
Set request attributes for the IP address, Hostname, protocol, and port used for the request. |
|
|
Whether to enable access log rotation. |
|
|
Log file name suffix. |
|
|
Comma-separated list of additional patterns that match jars to ignore for TLD scanning. The special '?' and '*' characters can be used in the pattern to match one and only one character and zero or more characters respectively. |
||
Delay between the invocation of backgroundProcess methods. If a duration suffix is not specified, seconds will be used. |
|
|
Tomcat base directory. If not specified, a temporary directory is used. |
||
Amount of time the connector will wait, after accepting a connection, for the request URI line to be presented. |
||
Time to wait for another HTTP request before the connection is closed. When not set the connectionTimeout is used. When set to -1 there will be no timeout. |
||
Maximum number of connections that the server accepts and processes at any given time. Once the limit has been reached, the operating system may still accept connections based on the "acceptCount" property. |
|
|
Maximum size of the form content in any HTTP post request. |
|
|
Maximum size of the HTTP response header. |
|
|
Maximum number of HTTP requests that can be pipelined before the connection is closed. When set to 0 or 1, keep-alive and pipelining are disabled. When set to -1, an unlimited number of pipelined or keep-alive requests are allowed. |
|
|
Maximum amount of request body to swallow. |
|
|
Whether Tomcat's MBean Registry should be enabled. |
|
|
Maximum number of idle processors that will be retained in the cache and reused with a subsequent request. When set to -1 the cache will be unlimited with a theoretical maximum size equal to the maximum number of connections. |
|
|
Whether requests to the context root should be redirected by appending a / to the path. When using SSL terminated at a proxy, this property should be set to false. |
|
|
Comma-separated list of additional unencoded characters that should be allowed in URI paths. Only "< > [ \ ] ^ ` { | }" are allowed. |
||
Comma-separated list of additional unencoded characters that should be allowed in URI query strings. Only "< > [ \ ] ^ ` { | }" are allowed. |
||
Name of the HTTP header from which the remote host is extracted. |
|
|
Regular expression that matches proxies that are to be trusted. |
|
|
Name of the HTTP header used to override the original port value. |
|
|
Header that holds the incoming protocol, usually named "X-Forwarded-Proto". |
||
Value of the protocol header indicating whether the incoming request uses SSL. |
|
|
Name of the HTTP header from which the remote IP is extracted. For instance, 'X-FORWARDED-FOR'. |
||
Regular expression defining proxies that are trusted when they appear in the "remote-ip-header" header. |
||
Whether static resource caching is permitted for this web application. |
|
|
Time-to-live of the static resource cache. |
||
Maximum amount of worker threads. |
|
|
Minimum amount of worker threads. |
|
|
Character encoding to use to decode the URI. |
|
|
Whether HTTP 1.1 and later location headers generated by a call to sendRedirect will use relative or absolute redirects. |
|
|
Undertow access log directory. |
||
Whether to enable the access log. |
|
|
Format pattern for access logs. |
|
|
Log file name prefix. |
|
|
Whether to enable access log rotation. |
|
|
Log file name suffix. |
|
|
Whether the 'Connection: keep-alive' header should be added to all responses, even if not required by the HTTP specification. |
|
|
Size of each buffer. The default is derived from the maximum amount of memory that is available to the JVM. |
||
Whether encoded slash characters (%2F) should be decoded. Decoding can cause security problems if a front-end proxy does not perform the same decoding. Only enable this if you have a legacy application that requires it. When set, server.undertow.allow-encoded-slash has no effect. |
||
Whether the URL should be decoded. When disabled, percent-encoded characters in the URL will be left as-is. |
|
|
Whether to allocate buffers outside the Java heap. The default is derived from the maximum amount of memory that is available to the JVM. |
||
Whether servlet filters should be initialized on startup. |
|
|
Maximum number of cookies that are allowed. This limit exists to prevent hash collision based DOS attacks. |
|
|
Maximum number of headers that are allowed. This limit exists to prevent hash collision based DOS attacks. |
||
Maximum size of the HTTP post content. When the value is -1, the default, the size is unlimited. |
|
|
Maximum number of query or path parameters that are allowed. This limit exists to prevent hash collision based DOS attacks. |
||
Amount of time a connection can sit idle without processing a request, before it is closed by the server. |
||
Server options as defined in io.undertow.UndertowOptions. |
||
Socket options as defined in org.xnio.Options. |
||
Whether to preserve the path of a request when it is forwarded. |
|
|
Number of I/O threads to create for the worker. The default is derived from the number of available processors. |
||
Number of worker threads. The default is 8 times the number of I/O threads. |
||
Charset used to decode URLs. |
|
.A.12. Security Properties
Name | Description | Default Value |
---|---|---|
Security filter chain dispatcher types for Servlet-based web applications. |
|
|
Security filter chain order for Servlet-based web applications. |
|
|
Registered clients of the Authorization Server. |
||
|
Authorization Server's OAuth 2.0 Authorization Endpoint. |
|
|
Authorization Server's OAuth 2.0 Device Authorization Endpoint. |
|
|
Authorization Server's OAuth 2.0 Device Verification Endpoint. |
|
|
Authorization Server's JWK Set Endpoint. |
|
|
Authorization Server's OpenID Connect 1.0 Client Registration Endpoint. |
|
|
Authorization Server's OpenID Connect 1.0 Logout Endpoint. |
|
|
Authorization Server's OpenID Connect 1.0 UserInfo Endpoint. |
|
|
Authorization Server's OAuth 2.0 Token Introspection Endpoint. |
|
|
Authorization Server's OAuth 2.0 Token Revocation Endpoint. |
|
|
Authorization Server's OAuth 2.0 Token Endpoint. |
|
URL of the Authorization Server's Issuer Identifier. |
||
OAuth provider details. |
||
OAuth client registrations. |
||
Identifies the recipients that the JWT is intended for. |
||
URI that can either be an OpenID Connect discovery endpoint or an OAuth 2.0 Authorization Server Metadata endpoint defined by RFC 8414. |
||
JSON Web Key URI to use to verify the JWT token. |
||
JSON Web Algorithms used for verifying the digital signatures. |
|
|
|
Location of the file containing the public key used to verify a JWT. |
|
Client id used to authenticate with the token introspection endpoint. |
||
|
Client secret used to authenticate with the token introspection endpoint. |
|
|
OAuth 2.0 endpoint through which token introspection is accomplished. |
|
SAML2 relying party registrations. |
||
Default user name. |
|
|
Password for the default user name. |
||
Granted roles for the default user name. |
.A.13. RSocket Properties
Name | Description | Default Value |
---|---|---|
Network address to which the server should bind. |
||
Maximum transmission unit. Frames larger than the specified value are fragmented. |
||
Path under which RSocket handles requests (only works with websocket transport). |
||
Server port. |
||
Whether the websocket compression extension is enabled. |
|
|
Whether to proxy websocket ping frames or respond to them. |
|
|
Maximum allowable frame payload length. |
|
|
Sub-protocols to use in websocket handshake signature. |
||
The name of a configured SSL bundle. |
||
Path to a PEM-encoded SSL certificate file. |
||
Path to a PEM-encoded private key file for the SSL certificate. |
||
Supported SSL ciphers. |
||
Client authentication mode. Requires a trust store. |
||
Whether to enable SSL support. |
|
|
Enabled SSL protocols. |
||
Alias that identifies the key in the key store. |
||
Password used to access the key in the key store. |
||
Path to the key store that holds the SSL certificate (typically a jks file). |
||
Password used to access the key store. |
||
Provider for the key store. |
||
Type of the key store. |
||
SSL protocol to use. |
|
|
Path to a PEM-encoded SSL certificate authority file. |
||
Path to a PEM-encoded private key file for the SSL certificate authority. |
||
Trust store that holds SSL certificates. |
||
Password used to access the trust store. |
||
Provider for the trust store. |
||
Type of the trust store. |
||
RSocket transport protocol. |
|
.A.14. Actuator Properties
Name | Description | Default Value |
---|---|---|
AppOptics API token. |
||
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Whether to ship a floored time, useful when sending measurements from multiple hosts to align them on a given time boundary. |
|
|
Tag that will be mapped to "@host" when shipping metrics to AppOptics. |
|
|
Read timeout for requests to this backend. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
URI to ship metrics to. |
|
|
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Frequency for refreshing config settings from the LWC service. |
|
|
Time to live for subscriptions from the LWC service. |
|
|
URI for the Atlas LWC endpoint to retrieve current subscriptions. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
URI for the Atlas LWC endpoint to evaluate the data for a subscription. |
|
|
Whether to enable streaming to Atlas LWC. |
|
|
Whether expressions with the same step size as Atlas publishing should be ignored for streaming. Used for cases where data being published to Atlas is also sent into streaming from the backend. |
|
|
Step size (reporting frequency) to use for streaming to Atlas LWC. This is the highest supported resolution for getting an on-demand stream of the data. It must be less than or equal to management.metrics.export.atlas.step and management.metrics.export.atlas.step should be an even multiple of this value. |
|
|
Time to live for meters that do not have any activity. After this period the meter will be considered expired and will not get reported. |
|
|
Number of threads to use with the metrics publishing scheduler. |
|
|
Read timeout for requests to this backend. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
URI of the Atlas server. |
|
|
Whether to enable storage of audit events. |
|
|
Whether to enable extended Cloud Foundry actuator endpoints. |
|
|
Whether to skip SSL verification for Cloud Foundry actuator endpoint security calls. |
|
|
Datadog API key. |
||
Datadog application key. Not strictly required, but improves the Datadog experience by sending meter descriptions, types, and base units to Datadog. |
||
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether to publish descriptions metadata to Datadog. Turn this off to minimize the amount of metadata sent. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Tag that will be mapped to "host" when shipping metrics to Datadog. |
|
|
Read timeout for requests to this backend. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
URI to ship metrics to. Set this if you need to publish metrics to a Datadog site other than US, or to an internal proxy en-route to Datadog. |
|
|
Whether to enable default metrics exporters. |
|
|
Dynatrace authentication token. |
||
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Read timeout for requests to this backend. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
URI to ship metrics to. Should be used for SaaS, self-managed instances or to en-route through an internal proxy. |
||
ID of the custom device that is exporting metrics to Dynatrace. |
||
Group for exported metrics. Used to specify custom device group name in the Dynatrace UI. |
||
Technology type for exported metrics. Used to group metrics under a logical technology name in the Dynatrace UI. |
|
|
Default dimensions that are added to all metrics in the form of key-value pairs. These are overwritten by Micrometer tags if they use the same key. |
||
|
Whether to enable Dynatrace metadata export. |
|
|
Whether to export meter metadata (unit and description) to the Dynatrace backend. |
|
Prefix string that is added to all exported metrics. |
||
|
Whether to fall back to the built-in micrometer instruments for Timer and DistributionSummary. |
|
Base64-encoded credentials string. Mutually exclusive with user-name and password. |
||
Whether to create the index automatically if it does not exist. |
|
|
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Host to export metrics to. |
|
|
Index to export metrics to. |
|
|
Index date format used for rolling indices. Appended to the index name. |
|
|
Prefix to separate the index name from the date format used for rolling indices. |
|
|
Login password of the Elastic server. Mutually exclusive with api-key-credentials. |
||
Ingest pipeline name. By default, events are not pre-processed. |
||
Read timeout for requests to this backend. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
Name of the timestamp field. |
|
|
Login user of the Elastic server. Mutually exclusive with api-key-credentials. |
||
Maximum time that a response can be cached. |
|
|
Whether to enable the auditevents endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the beans endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the caches endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the conditions endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the configprops endpoint. |
|
|
Roles used to determine whether a user is authorized to be shown unsanitized values. When empty, all authenticated users are authorized. |
||
When to show unsanitized values. |
||
Maximum time that a response can be cached. |
|
|
Whether to enable the env endpoint. |
|
|
Roles used to determine whether a user is authorized to be shown unsanitized values. When empty, all authenticated users are authorized. |
||
When to show unsanitized values. |
||
Maximum time that a response can be cached. |
|
|
Whether to enable the flyway endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the health endpoint. |
|
|
Health endpoint groups. |
||
Threshold after which a warning will be logged for slow health indicators. |
|
|
Whether to make the liveness and readiness health groups available on the main server port. |
|
|
Whether to enable liveness and readiness probes. |
|
|
Roles used to determine whether a user is authorized to be shown details. When empty, all authenticated users are authorized. |
||
When to show components. If not specified the 'show-details' setting will be used. |
||
When to show full health details. |
|
|
Mapping of health statuses to HTTP status codes. By default, registered health statuses map to sensible defaults (for example, UP maps to 200). |
||
Comma-separated list of health statuses in order of severity. |
|
|
Whether to validate health group membership on startup. Validation fails if a group includes or excludes a health contributor that does not exist. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the heapdump endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the httpexchanges endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the info endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the integrationgraph endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the liquibase endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the logfile endpoint. |
|
|
External Logfile to be accessed. Can be used if the logfile is written by output redirect and not by the logging system itself. |
||
Maximum time that a response can be cached. |
|
|
Whether to enable the loggers endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the mappings endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the metrics endpoint. |
|
|
Whether to enable the prometheus endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the quartz endpoint. |
|
|
Roles used to determine whether a user is authorized to be shown unsanitized job or trigger values. When empty, all authenticated users are authorized. |
||
When to show unsanitized job or trigger values. |
||
Maximum time that a response can be cached. |
|
|
Whether to enable the scheduledtasks endpoint. |
|
|
Whether to enable the sessions endpoint. |
|
|
Whether to enable the shutdown endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the startup endpoint. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the threaddump endpoint. |
|
|
Whether to enable or disable all endpoints by default. |
||
Whether to use an isolated object mapper to serialize endpoint JSON. |
|
|
Endpoints JMX domain name. Fallback to 'spring.jmx.default-domain' if set. |
|
|
Endpoint IDs that should be excluded or '*' for all. |
||
Endpoint IDs that should be included or '*' for all. |
|
|
Additional static properties to append to all ObjectNames of MBeans representing Endpoints. |
||
Whether to transparently migrate legacy endpoint IDs. |
|
|
Base path for Web endpoints. Relative to the servlet context path (server.servlet.context-path) or WebFlux base path (spring.webflux.base-path) when the management server is sharing the main server port. Relative to the management server base path (management.server.base-path) when a separate management server port (management.server.port) is configured. |
|
|
Whether credentials are supported. When not set, credentials are not supported. |
||
Comma-separated list of headers to allow in a request. '*' allows all headers. |
||
Comma-separated list of methods to allow. '*' allows all methods. When not set, defaults to GET. |
||
Comma-separated list of origin patterns to allow. Unlike allowed origins which only supports '*', origin patterns are more flexible (for example 'https://*.example.com') and can be used when credentials are allowed. When no allowed origin patterns or allowed origins are set, CORS support is disabled. |
||
Comma-separated list of origins to allow. '*' allows all origins. When credentials are allowed, '*' cannot be used and origin patterns should be configured instead. When no allowed origins or allowed origin patterns are set, CORS support is disabled. |
||
Comma-separated list of headers to include in a response. |
||
How long the response from a pre-flight request can be cached by clients. If a duration suffix is not specified, seconds will be used. |
|
|
Whether the discovery page is enabled. |
|
|
Endpoint IDs that should be excluded or '*' for all. |
||
Endpoint IDs that should be included or '*' for all. |
|
|
Mapping between endpoint IDs and the path that should expose them. |
||
UDP addressing mode, either unicast or multicast. |
|
|
Base time unit used to report durations. |
|
|
Whether exporting of metrics to Ganglia is enabled. |
|
|
Host of the Ganglia server to receive exported metrics. |
|
|
Port of the Ganglia server to receive exported metrics. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
Time to live for metrics on Ganglia. Set the multicast Time-To-Live to be one greater than the number of hops (routers) between the hosts. |
|
|
Base time unit used to report durations. |
|
|
Whether exporting of metrics to Graphite is enabled. |
|
|
Whether Graphite tags should be used, as opposed to a hierarchical naming convention. Enabled by default unless "tagsAsPrefix" is set. |
||
Host of the Graphite server to receive exported metrics. |
|
|
Port of the Graphite server to receive exported metrics. |
|
|
Protocol to use while shipping data to Graphite. |
|
|
Base time unit used to report rates. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
For the hierarchical naming convention, turn the specified tag keys into part of the metric prefix. Ignored if "graphiteTagsEnabled" is true. |
|
|
Whether to enable Cassandra health check. |
|
|
Whether to enable Couchbase health check. |
|
|
Whether to enable database health check. |
|
|
Whether to ignore AbstractRoutingDataSources when creating database health indicators. |
|
|
Whether to enable default health indicators. |
|
|
Whether to enable disk space health check. |
|
|
Path used to compute the available disk space. |
||
Minimum disk space that should be available. |
|
|
Whether to enable Elasticsearch health check. |
|
|
Whether to enable InfluxDB health check. |
|
|
Whether to enable JMS health check. |
|
|
Whether to enable LDAP health check. |
|
|
Whether to enable liveness state health check. |
|
|
Whether to enable Mail health check. |
|
|
Whether to enable MongoDB health check. |
|
|
Whether to enable Neo4j health check. |
|
|
Whether to enable ping health check. |
|
|
Whether to enable RabbitMQ health check. |
|
|
Whether to enable readiness state health check. |
|
|
Whether to enable Redis health check. |
|
|
Whether to enable HTTP request-response exchange recording. |
|
|
Items to be included in the exchange recording. Defaults to request headers (excluding Authorization and Cookie), response headers (excluding Set-Cookie), and time taken. |
|
|
Humio API token. |
||
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Read timeout for requests to this backend. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
Humio tags describing the data source in which metrics will be stored. Humio tags are a distinct concept from Micrometer's tags. Micrometer's tags are used to divide metrics along dimensional boundaries. |
||
URI to ship metrics to. If you need to publish metrics to an internal proxy en-route to Humio, you can define the location of the proxy with this. |
|
|
API version of InfluxDB to use. Defaults to 'v1' unless an org is configured. If an org is configured, defaults to 'v2'. |
||
Whether to create the Influx database if it does not exist before attempting to publish metrics to it. InfluxDB v1 only. |
|
|
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Bucket for metrics. Use either the bucket name or ID. Defaults to the value of the db property if not set. InfluxDB v2 only. |
||
Whether to enable GZIP compression of metrics batches published to Influx. |
|
|
Connection timeout for requests to this backend. |
|
|
Write consistency for each point. |
|
|
Database to send metrics to. InfluxDB v1 only. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Org to write metrics to. InfluxDB v2 only. |
||
Login password of the Influx server. InfluxDB v1 only. |
||
Read timeout for requests to this backend. |
|
|
Time period for which Influx should retain data in the current database. For instance 7d, check the influx documentation for more details on the duration format. InfluxDB v1 only. |
||
Retention policy to use (Influx writes to the DEFAULT retention policy if one is not specified). InfluxDB v1 only. |
||
|
How many copies of the data are stored in the cluster. Must be 1 for a single node instance. InfluxDB v1 only. |
|
Time range covered by a shard group. For instance 2w, check the influx documentation for more details on the duration format. InfluxDB v1 only. |
||
Step size (i.e. reporting frequency) to use. |
|
|
Authentication token to use with calls to the InfluxDB backend. For InfluxDB v1, the Bearer scheme is used. For v2, the Token scheme is used. |
||
URI of the Influx server. |
|
|
Login user of the Influx server. InfluxDB v1 only. |
||
Whether to enable build info. |
|
|
Whether to enable default info contributors. |
|
|
Whether to enable environment info. |
|
|
Whether to enable git info. |
|
|
Mode to use to expose git information. |
|
|
Whether to enable Java info. |
|
|
Whether to enable Operating System info. |
|
|
Metrics JMX domain name. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Login password of the KairosDB server. |
||
Read timeout for requests to this backend. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
URI of the KairosDB server. |
|
|
Login user of the KairosDB server. |
||
Whether to enable auto-timing. |
|
|
Percentiles for which additional time series should be published. |
||
|
Whether to publish percentile histograms. |
|
Name of the metric for sent requests. |
|
|
Number of histograms for meter IDs starting with the specified name to keep in the ring buffer. The longest match wins, the key `all` can also be used to configure all meters. |
||
Maximum amount of time that samples for meter IDs starting with the specified name are accumulated to decaying distribution statistics before they are reset and rotated. The longest match wins, the key `all` can also be used to configure all meters. |
||
Maximum value that meter IDs starting with the specified name are expected to observe. The longest match wins. Values can be specified as a double or as a Duration value (for timer meters, defaulting to ms if no unit specified). |
||
Minimum value that meter IDs starting with the specified name are expected to observe. The longest match wins. Values can be specified as a double or as a Duration value (for timer meters, defaulting to ms if no unit specified). |
||
Specific computed non-aggregable percentiles to ship to the backend for meter IDs starting-with the specified name. The longest match wins, the key 'all' can also be used to configure all meters. |
||
Whether meter IDs starting with the specified name should publish percentile histograms. For monitoring systems that support aggregable percentile calculation based on a histogram, this can be set to true. For other systems, this has no effect. The longest match wins, the key 'all' can also be used to configure all meters. |
||
Specific service-level objective boundaries for meter IDs starting with the specified name. The longest match wins. Counters will be published for each specified boundary. Values can be specified as a double or as a Duration value (for timer meters, defaulting to ms if no unit specified). |
||
Whether meter IDs starting with the specified name should be enabled. The longest match wins, the key 'all' can also be used to configure all meters. |
||
Whether to enable Mongo client command metrics. |
|
|
Whether to enable Mongo connection pool metrics. |
|
|
Comma-separated list of paths to report disk metrics for. |
|
|
Whether auto-configured MeterRegistry implementations should be bound to the global static registry on Metrics. For testing, set this to 'false' to maximize test independence. |
|
|
Maximum number of unique URI tag values allowed. After the max number of tag values is reached, metrics with additional tag values are denied by filter. |
|
|
Maximum number of unique URI tag values allowed. After the max number of tag values is reached, metrics with additional tag values are denied by filter. |
|
|
New Relic account ID. |
||
New Relic API key. |
||
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Client provider type to use. |
||
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
The event type that should be published. This property will be ignored if 'meter-name-event-type-enabled' is set to 'true'. |
|
|
|
Whether to send the meter name as the event type instead of using the 'event-type' configuration property value. Can be set to 'true' if New Relic guidelines are not being followed or event types consistent with previous Spring Boot releases are required. |
|
Read timeout for requests to this backend. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
URI to ship metrics to. |
|
|
Whether observations starting with the specified name should be enabled. The longest match wins, the key 'all' can also be used to configure all observations. |
||
Name of the observation for client requests. |
|
|
Name of the observation for server requests. |
|
|
Common key-values that are applied to every observation. |
||
Whether to tag actual query parameter values. |
|
|
Resource attributes. |
||
Aggregation temporality of sums. It defines the way additive values are expressed. This setting depends on the backend you use, some only support one temporality. |
||
Time unit for exported metrics. |
|
|
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Headers for the exported metrics. |
||
Read timeout for requests to this backend. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
URI of the OLTP server. |
|
|
Method used to compress the payload. |
|
|
URL to the OTel collector's HTTP API. |
||
Custom HTTP headers you want to pass to the collector, for example auth headers. |
||
Call timeout for the OTel Collector to process an exported batch of data. This timeout spans the entire call: resolving DNS, connecting, writing the request body, server processing, and reading the response body. If the call requires redirects or retries all must complete within one timeout period. |
|
|
Whether to enable publishing descriptions as part of the scrape payload to Prometheus. Turn this off to minimize the amount of data sent on each scrape. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Histogram type for backing DistributionSummary and Timer. |
|
|
Base URL for the Pushgateway. |
|
|
Enable publishing over a Prometheus Pushgateway. |
|
|
|
Grouping key for the pushed metrics. |
|
Job identifier for this application instance. |
||
Login password of the Prometheus Pushgateway. |
||
Frequency with which to push metrics. |
|
|
|
Operation that should be performed on shutdown. |
|
Login user of the Prometheus Pushgateway. |
||
Step size (i.e. reporting frequency) to use. |
|
|
Add the "X-Application-Context" HTTP header in each response. |
|
|
Network address to which the management endpoints should bind. Requires a custom management.server.port. |
||
Management endpoint base path (for instance, '/management'). Requires a custom management.server.port. |
||
Management endpoint HTTP port (uses the same port as the application by default). Configure a different port to use management-specific SSL. |
||
The name of a configured SSL bundle. |
||
Path to a PEM-encoded SSL certificate file. |
||
Path to a PEM-encoded private key file for the SSL certificate. |
||
Supported SSL ciphers. |
||
Client authentication mode. Requires a trust store. |
||
Whether to enable SSL support. |
|
|
Enabled SSL protocols. |
||
Alias that identifies the key in the key store. |
||
Password used to access the key in the key store. |
||
Path to the key store that holds the SSL certificate (typically a jks file). |
||
Password used to access the key store. |
||
Provider for the key store. |
||
Type of the key store. |
||
SSL protocol to use. |
|
|
Path to a PEM-encoded SSL certificate authority file. |
||
Path to a PEM-encoded private key file for the SSL certificate authority. |
||
Trust store that holds SSL certificates. |
||
Password used to access the trust store. |
||
Provider for the trust store. |
||
Type of the trust store. |
||
SignalFX access token. |
||
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Type of histogram to publish. |
|
|
Read timeout for requests to this backend. |
|
|
Uniquely identifies the app instance that is publishing metrics to SignalFx. Defaults to the local host name. |
||
Step size (i.e. reporting frequency) to use. |
|
|
URI to ship metrics to. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Counting mode. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Prefix for metric type. Valid prefixes are described in the Google Cloud documentation (https://cloud.google.com/monitoring/custom-metrics#identifier). |
|
|
Identifier of the Google Cloud project to monitor. |
||
Read timeout for requests to this backend. |
|
|
Monitored resource's labels. |
||
Monitored resource type. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
|
Whether to use semantically correct metric types. When false, counter metrics are published as the GAUGE MetricKind. When true, counter metrics are published as the CUMULATIVE MetricKind. |
|
Whether measurements should be buffered before sending to the StatsD server. |
|
|
Whether exporting of metrics to StatsD is enabled. |
|
|
StatsD line protocol to use. |
|
|
Host of the StatsD server to receive exported metrics. |
|
|
Total length of a single payload should be kept within your network's MTU. |
|
|
How often gauges will be polled. When a gauge is polled, its value is recalculated and if the value has changed (or publishUnchangedMeters is true), it is sent to the StatsD server. |
|
|
Port of the StatsD server to receive exported metrics. |
|
|
Protocol of the StatsD server to receive exported metrics. |
|
|
Whether to send unchanged meters to the StatsD server. |
|
|
Step size to use in computing windowed statistics like max. To get the most out of these statistics, align the step interval to be close to your scrape interval. |
|
|
Whether to enable correlation of the baggage context with logging contexts. |
|
|
List of fields that should be correlated with the logging context. That means that these fields would end up as key-value pairs in e.g. MDC. |
||
Whether to enable Micrometer Tracing baggage propagation. |
|
|
List of fields that are referenced the same in-process as it is on the wire. For example, the field "x-vcap-request-id" would be set as-is including the prefix. |
||
Whether the propagation type and tracing backend support sharing the span ID between client and server spans. Requires B3 propagation and a compatible backend. |
|
|
Whether auto-configuration of tracing is enabled. |
|
|
Tracing context propagation types consumed by the application. |
|
|
Tracing context propagation types produced by the application. |
|
|
Tracing context propagation types produced and consumed by the application. Setting this property overrides the more fine-grained propagation type properties. |
||
Probability in the range from 0.0 to 1.0 that a trace will be sampled. |
|
|
API token used when publishing metrics and traces directly to the Wavefront API host. |
||
Type of the API token. |
||
Wavefront Cluster name used in ApplicationTags. |
||
Wavefront custom tags used in ApplicationTags. |
||
Wavefront 'Application' name used in ApplicationTags. |
|
|
Wavefront 'Service' name used in ApplicationTags, falling back to 'spring.application.name'. If both are unset it defaults to 'unnamed_service'. |
||
Wavefront Shard name used in ApplicationTags. |
||
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Connection timeout for requests to this backend. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Global prefix to separate metrics originating from this app's instrumentation from those originating from other Wavefront integrations when viewed in the Wavefront UI. |
||
Read timeout for requests to this backend. |
|
|
Whether to report histogram distributions aggregated into day intervals. |
|
|
|
Whether to report histogram distributions aggregated into hour intervals. |
|
|
Whether to report histogram distributions aggregated into minute intervals. |
|
Step size (i.e. reporting frequency) to use. |
|
|
Number of measurements per request to use for Wavefront. If more measurements are found, then multiple requests will be made. |
|
|
Flush interval to send queued messages. |
|
|
Maximum size of queued messages. |
|
|
Maximum size of a message. |
||
Unique identifier for the app instance that is the source of metrics and traces being published to Wavefront. Defaults to the local host name. |
||
Customized span tags for RED metrics. |
||
URI to ship metrics and traces to. |
|
|
Connection timeout for requests to Zipkin. |
|
|
URL to the Zipkin API. |
|
|
Read timeout for requests to Zipkin. |
|
.A.15. Devtools Properties
Name | Description | Default Value |
---|---|---|
Whether to enable development property defaults. |
|
|
Whether to enable a livereload.com-compatible server. |
|
|
Server port. |
|
|
Context path used to handle the remote connection. |
|
|
The host of the proxy to use to connect to the remote application. |
||
The port of the proxy to use to connect to the remote application. |
||
Whether to enable remote restart. |
|
|
A shared secret required to establish a connection (required to enable remote support). |
||
HTTP header used to transfer the shared secret. |
|
|
Additional patterns that should be excluded from triggering a full restart. |
||
Additional paths to watch for changes. |
||
Whether to enable automatic restart. |
|
|
Patterns that should be excluded from triggering a full restart. |
|
|
Whether to log the condition evaluation delta upon restart. |
|
|
Amount of time to wait between polling for classpath changes. |
|
|
Amount of quiet time required without any classpath changes before a restart is triggered. |
|
|
Name of a specific file that, when changed, triggers the restart check. Must be a simple name (without any path) of a file that appears on your classpath. If not specified, any classpath file change triggers the restart. |
.A.16. Docker Compose Properties
Name | Description | Default Value |
---|---|---|
Whether docker compose support is enabled. |
|
|
Path to a specific docker compose configuration file. |
||
Hostname or IP of the machine where the docker containers are started. |
||
Docker compose lifecycle management. |
|
|
Docker compose profiles that should be active. |
||
Timeout for connections. |
|
|
Timeout for reads. |
|
|
Timeout of the readiness checks. |
|
|
Wait strategy to use. |
|
|
Whether to skip in tests. |
|
|
Command used to start docker compose. |
|
|
Log level for output. |
|
|
Command used to stop docker compose. |
|
|
Timeout for stopping Docker Compose. Use '0' for forced stop. |
|
.A.17. Testcontainers Properties
Name | Description | Default Value |
---|---|---|
Testcontainers startup modes. |
|
Appendix B: Configuration Metadata
Spring Boot jars include metadata files that provide details of all supported configuration properties.
The files are designed to let IDE developers offer contextual help and “code completion” as users are working with application.properties
or application.yaml
files.
The majority of the metadata file is generated automatically at compile time by processing all items annotated with @ConfigurationProperties
.
However, it is possible to write part of the metadata manually for corner cases or more advanced use cases.
.B.1. Metadata Format
Configuration metadata files are located inside jars under META-INF/spring-configuration-metadata.json
.
They use a JSON format with items categorized under either “groups” or “properties” and additional values hints categorized under "hints", as shown in the following example:
{"groups": [
{
"name": "server",
"type": "org.springframework.boot.autoconfigure.web.ServerProperties",
"sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties"
},
{
"name": "spring.jpa.hibernate",
"type": "org.springframework.boot.autoconfigure.orm.jpa.JpaProperties$Hibernate",
"sourceType": "org.springframework.boot.autoconfigure.orm.jpa.JpaProperties",
"sourceMethod": "getHibernate()"
}
...
],"properties": [
{
"name": "server.port",
"type": "java.lang.Integer",
"sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties"
},
{
"name": "server.address",
"type": "java.net.InetAddress",
"sourceType": "org.springframework.boot.autoconfigure.web.ServerProperties"
},
{
"name": "spring.jpa.hibernate.ddl-auto",
"type": "java.lang.String",
"description": "DDL mode. This is actually a shortcut for the \"hibernate.hbm2ddl.auto\" property.",
"sourceType": "org.springframework.boot.autoconfigure.orm.jpa.JpaProperties$Hibernate"
}
...
],"hints": [
{
"name": "spring.jpa.hibernate.ddl-auto",
"values": [
{
"value": "none",
"description": "Disable DDL handling."
},
{
"value": "validate",
"description": "Validate the schema, make no changes to the database."
},
{
"value": "update",
"description": "Update the schema if necessary."
},
{
"value": "create",
"description": "Create the schema and destroy previous data."
},
{
"value": "create-drop",
"description": "Create and then destroy the schema at the end of the session."
}
]
}
]}
Each “property” is a configuration item that the user specifies with a given value.
For example, server.port
and server.address
might be specified in your application.properties
/application.yaml
, as follows:
server.port=9090
server.address=127.0.0.1
server:
port: 9090
address: 127.0.0.1
The “groups” are higher level items that do not themselves specify a value but instead provide a contextual grouping for properties.
For example, the server.port
and server.address
properties are part of the server
group.
It is not required that every “property” has a “group”. Some properties might exist in their own right. |
Finally, “hints” are additional information used to assist the user in configuring a given property.
For example, when a developer is configuring the spring.jpa.hibernate.ddl-auto
property, a tool can use the hints to offer some auto-completion help for the none
, validate
, update
, create
, and create-drop
values.
Group Attributes
The JSON object contained in the groups
array can contain the attributes shown in the following table:
Name | Type | Purpose |
---|---|---|
|
String |
The full name of the group. This attribute is mandatory. |
|
String |
The class name of the data type of the group.
For example, if the group were based on a class annotated with |
|
String |
A short description of the group that can be displayed to users.
If no description is available, it may be omitted.
It is recommended that descriptions be short paragraphs, with the first line providing a concise summary.
The last line in the description should end with a period ( |
|
String |
The class name of the source that contributed this group.
For example, if the group were based on a |
|
String |
The full name of the method (include parenthesis and argument types) that contributed this group (for example, the name of a |
Property Attributes
The JSON object contained in the properties
array can contain the attributes described in the following table:
Name | Type | Purpose |
---|---|---|
|
String |
The full name of the property.
Names are in lower-case period-separated form (for example, |
|
String |
The full signature of the data type of the property (for example, |
|
String |
A short description of the property that can be displayed to users.
If no description is available, it may be omitted.
It is recommended that descriptions be short paragraphs, with the first line providing a concise summary.
The last line in the description should end with a period ( |
|
String |
The class name of the source that contributed this property.
For example, if the property were from a class annotated with |
|
Object |
The default value, which is used if the property is not specified. If the type of the property is an array, it can be an array of value(s). If the default value is unknown, it may be omitted. |
|
Deprecation |
Specify whether the property is deprecated.
If the field is not deprecated or if that information is not known, it may be omitted.
The next table offers more detail about the |
The JSON object contained in the deprecation
attribute of each properties
element can contain the following attributes:
Name | Type | Purpose |
---|---|---|
|
String |
The level of deprecation, which can be either |
|
String |
A short description of the reason why the property was deprecated.
If no reason is available, it may be omitted.
It is recommended that descriptions be short paragraphs, with the first line providing a concise summary.
The last line in the description should end with a period ( |
|
String |
The full name of the property that replaces this deprecated property. If there is no replacement for this property, it may be omitted. |
|
String |
The version in which the property became deprecated. Can be omitted. |
Prior to Spring Boot 1.3, a single deprecated boolean attribute can be used instead of the deprecation element.
This is still supported in a deprecated fashion and should no longer be used.
If no reason and replacement are available, an empty deprecation object should be set.
|
Deprecation can also be specified declaratively in code by adding the @DeprecatedConfigurationProperty
annotation to the getter exposing the deprecated property.
For instance, assume that the my.app.target
property was confusing and was renamed to my.app.name
.
The following example shows how to handle that situation:
@ConfigurationProperties("my.app")
public class MyProperties {
private String name;
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
@Deprecated
@DeprecatedConfigurationProperty(replacement = "my.app.name")
public String getTarget() {
return this.name;
}
@Deprecated
public void setTarget(String target) {
this.name = target;
}
}
There is no way to set a level .
warning is always assumed, since code is still handling the property.
|
The preceding code makes sure that the deprecated property still works (delegating to the name
property behind the scenes).
Once the getTarget
and setTarget
methods can be removed from your public API, the automatic deprecation hint in the metadata goes away as well.
If you want to keep a hint, adding manual metadata with an error
deprecation level ensures that users are still informed about that property.
Doing so is particularly useful when a replacement
is provided.
Hint Attributes
The JSON object contained in the hints
array can contain the attributes shown in the following table:
Name | Type | Purpose |
---|---|---|
|
String |
The full name of the property to which this hint refers.
Names are in lower-case period-separated form (such as |
|
ValueHint[] |
A list of valid values as defined by the |
|
ValueProvider[] |
A list of providers as defined by the |
The JSON object contained in the values
attribute of each hint
element can contain the attributes described in the following table:
Name | Type | Purpose |
---|---|---|
|
Object |
A valid value for the element to which the hint refers. If the type of the property is an array, it can also be an array of value(s). This attribute is mandatory. |
|
String |
A short description of the value that can be displayed to users.
If no description is available, it may be omitted.
It is recommended that descriptions be short paragraphs, with the first line providing a concise summary.
The last line in the description should end with a period ( |
The JSON object contained in the providers
attribute of each hint
element can contain the attributes described in the following table:
Name | Type | Purpose |
---|---|---|
|
String |
The name of the provider to use to offer additional content assistance for the element to which the hint refers. |
|
JSON object |
Any additional parameter that the provider supports (check the documentation of the provider for more details). |
Repeated Metadata Items
Objects with the same “property” and “group” name can appear multiple times within a metadata file. For example, you could bind two separate classes to the same prefix, with each having potentially overlapping property names. While the same names appearing in the metadata multiple times should not be common, consumers of metadata should take care to ensure that they support it.
.B.2. Providing Manual Hints
To improve the user experience and further assist the user in configuring a given property, you can provide additional metadata that:
-
Describes the list of potential values for a property.
-
Associates a provider, to attach a well defined semantic to a property, so that a tool can discover the list of potential values based on the project’s context.
Value Hint
The name
attribute of each hint refers to the name
of a property.
In the initial example shown earlier, we provide five values for the spring.jpa.hibernate.ddl-auto
property: none
, validate
, update
, create
, and create-drop
.
Each value may have a description as well.
If your property is of type Map
, you can provide hints for both the keys and the values (but not for the map itself).
The special .keys
and .values
suffixes must refer to the keys and the values, respectively.
Assume a my.contexts
maps magic String
values to an integer, as shown in the following example:
@ConfigurationProperties("my")
public class MyProperties {
private Map<String, Integer> contexts;
}
The magic values are (in this example) are sample1
and sample2
.
In order to offer additional content assistance for the keys, you could add the following JSON to the manual metadata of the module:
{"hints": [
{
"name": "my.contexts.keys",
"values": [
{
"value": "sample1"
},
{
"value": "sample2"
}
]
}
]}
We recommend that you use an Enum for those two values instead.
If your IDE supports it, this is by far the most effective approach to auto-completion.
|
Value Providers
Providers are a powerful way to attach semantics to a property. In this section, we define the official providers that you can use for your own hints. However, your favorite IDE may implement some of these or none of them. Also, it could eventually provide its own.
As this is a new feature, IDE vendors must catch up with how it works. Adoption times naturally vary. |
The following table summarizes the list of supported providers:
Name | Description |
---|---|
|
Permits any additional value to be provided. |
|
Auto-completes the classes available in the project.
Usually constrained by a base class that is specified by the |
|
Handles the property as if it were defined by the type defined by the mandatory |
|
Auto-completes valid logger names and logger groups. Typically, package and class names available in the current project can be auto-completed as well as defined groups. |
|
Auto-completes the available bean names in the current project.
Usually constrained by a base class that is specified by the |
|
Auto-completes the available Spring profile names in the project. |
Only one provider can be active for a given property, but you can specify several providers if they can all manage the property in some way. Make sure to place the most powerful provider first, as the IDE must use the first one in the JSON section that it can handle. If no provider for a given property is supported, no special content assistance is provided, either. |
Any
The special any provider value permits any additional values to be provided. Regular value validation based on the property type should be applied if this is supported.
This provider is typically used if you have a list of values and any extra values should still be considered as valid.
The following example offers on
and off
as auto-completion values for system.state
:
{"hints": [
{
"name": "system.state",
"values": [
{
"value": "on"
},
{
"value": "off"
}
],
"providers": [
{
"name": "any"
}
]
}
]}
Note that, in the preceding example, any other value is also allowed.
Class Reference
The class-reference provider auto-completes classes available in the project. This provider supports the following parameters:
Parameter | Type | Default value | Description |
---|---|---|---|
|
|
none |
The fully qualified name of the class that should be assignable to the chosen value. Typically used to filter out-non candidate classes. Note that this information can be provided by the type itself by exposing a class with the appropriate upper bound. |
|
|
true |
Specify whether only concrete classes are to be considered as valid candidates. |
The following metadata snippet corresponds to the standard server.servlet.jsp.class-name
property that defines the JspServlet
class name to use:
{"hints": [
{
"name": "server.servlet.jsp.class-name",
"providers": [
{
"name": "class-reference",
"parameters": {
"target": "jakarta.servlet.http.HttpServlet"
}
}
]
}
]}
Handle As
The handle-as provider lets you substitute the type of the property to a more high-level type.
This typically happens when the property has a java.lang.String
type, because you do not want your configuration classes to rely on classes that may not be on the classpath.
This provider supports the following parameters:
Parameter | Type | Default value | Description |
---|---|---|---|
|
|
none |
The fully qualified name of the type to consider for the property. This parameter is mandatory. |
The following types can be used:
-
Any
java.lang.Enum
: Lists the possible values for the property. (We recommend defining the property with theEnum
type, as no further hint should be required for the IDE to auto-complete the values) -
java.nio.charset.Charset
: Supports auto-completion of charset/encoding values (such asUTF-8
) -
java.util.Locale
: auto-completion of locales (such asen_US
) -
org.springframework.util.MimeType
: Supports auto-completion of content type values (such astext/plain
) -
org.springframework.core.io.Resource
: Supports auto-completion of Spring’s Resource abstraction to refer to a file on the filesystem or on the classpath (such asclasspath:/sample.properties
)
If multiple values can be provided, use a Collection or Array type to teach the IDE about it.
|
The following metadata snippet corresponds to the standard spring.liquibase.change-log
property that defines the path to the changelog to use.
It is actually used internally as a org.springframework.core.io.Resource
but cannot be exposed as such, because we need to keep the original String value to pass it to the Liquibase API.
{"hints": [
{
"name": "spring.liquibase.change-log",
"providers": [
{
"name": "handle-as",
"parameters": {
"target": "org.springframework.core.io.Resource"
}
}
]
}
]}
Logger Name
The logger-name provider auto-completes valid logger names and logger groups. Typically, package and class names available in the current project can be auto-completed. If groups are enabled (default) and if a custom logger group is identified in the configuration, auto-completion for it should be provided. Specific frameworks may have extra magic logger names that can be supported as well.
This provider supports the following parameters:
Parameter | Type | Default value | Description |
---|---|---|---|
|
|
|
Specify whether known groups should be considered. |
Since a logger name can be any arbitrary name, this provider should allow any value but could highlight valid package and class names that are not available in the project’s classpath.
The following metadata snippet corresponds to the standard logging.level
property.
Keys are logger names, and values correspond to the standard log levels or any custom level.
As Spring Boot defines a few logger groups out-of-the-box, dedicated value hints have been added for those.
{"hints": [
{
"name": "logging.level.keys",
"values": [
{
"value": "root",
"description": "Root logger used to assign the default logging level."
},
{
"value": "sql",
"description": "SQL logging group including Hibernate SQL logger."
},
{
"value": "web",
"description": "Web logging group including codecs."
}
],
"providers": [
{
"name": "logger-name"
}
]
},
{
"name": "logging.level.values",
"values": [
{
"value": "trace"
},
{
"value": "debug"
},
{
"value": "info"
},
{
"value": "warn"
},
{
"value": "error"
},
{
"value": "fatal"
},
{
"value": "off"
}
],
"providers": [
{
"name": "any"
}
]
}
]}
Spring Bean Reference
The spring-bean-reference provider auto-completes the beans that are defined in the configuration of the current project. This provider supports the following parameters:
Parameter | Type | Default value | Description |
---|---|---|---|
|
|
none |
The fully qualified name of the bean class that should be assignable to the candidate. Typically used to filter out non-candidate beans. |
The following metadata snippet corresponds to the standard spring.jmx.server
property that defines the name of the MBeanServer
bean to use:
{"hints": [
{
"name": "spring.jmx.server",
"providers": [
{
"name": "spring-bean-reference",
"parameters": {
"target": "javax.management.MBeanServer"
}
}
]
}
]}
The binder is not aware of the metadata.
If you provide that hint, you still need to transform the bean name into an actual Bean reference using by the ApplicationContext .
|
Spring Profile Name
The spring-profile-name provider auto-completes the Spring profiles that are defined in the configuration of the current project.
The following metadata snippet corresponds to the standard spring.profiles.active
property that defines the name of the Spring profile(s) to enable:
{"hints": [
{
"name": "spring.profiles.active",
"providers": [
{
"name": "spring-profile-name"
}
]
}
]}
.B.3. Generating Your Own Metadata by Using the Annotation Processor
You can easily generate your own configuration metadata file from items annotated with @ConfigurationProperties
by using the spring-boot-configuration-processor
jar.
The jar includes a Java annotation processor which is invoked as your project is compiled.
Configuring the Annotation Processor
To use the processor, include a dependency on spring-boot-configuration-processor
.
With Maven the dependency should be declared as optional, as shown in the following example:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
With Gradle, the dependency should be declared in the annotationProcessor
configuration, as shown in the following example:
dependencies {
annotationProcessor "org.springframework.boot:spring-boot-configuration-processor"
}
If you are using an additional-spring-configuration-metadata.json
file, the compileJava
task should be configured to depend on the processResources
task, as shown in the following example:
tasks.named('compileJava') {
inputs.files(tasks.named('processResources'))
}
This dependency ensures that the additional metadata is available when the annotation processor runs during compilation.
If you are using AspectJ in your project, you need to make sure that the annotation processor runs only once.
There are several ways to do this.
With Maven, you can configure the
|
If you are using Lombok in your project, you need to make sure that its annotation processor runs before |
Automatic Metadata Generation
The processor picks up both classes and methods that are annotated with @ConfigurationProperties
.
If the class has a single parameterized constructor, one property is created per constructor parameter, unless the constructor is annotated with @Autowired
.
If the class has a constructor explicitly annotated with @ConstructorBinding
, one property is created per constructor parameter for that constructor.
Otherwise, properties are discovered through the presence of standard getters and setters with special handling for collection and map types (that is detected even if only a getter is present).
The annotation processor also supports the use of the @Data
, @Value
, @Getter
, and @Setter
lombok annotations.
Consider the following example:
@ConfigurationProperties(prefix = "my.server")
public class MyServerProperties {
/**
* Name of the server.
*/
private String name;
/**
* IP address to listen to.
*/
private String ip = "127.0.0.1";
/**
* Port to listener to.
*/
private int port = 9797;
This exposes three properties where my.server.name
has no default and my.server.ip
and my.server.port
defaults to "127.0.0.1"
and 9797
respectively.
The Javadoc on fields is used to populate the description
attribute. For instance, the description of my.server.ip
is "IP address to listen to.".
You should only use plain text with @ConfigurationProperties field Javadoc, since they are not processed before being added to the JSON.
|
The annotation processor applies a number of heuristics to extract the default value from the source model.
Default values have to be provided statically. In particular, do not refer to a constant defined in another class.
Also, the annotation processor cannot auto-detect default values for Enum
s and Collections
s.
For cases where the default value could not be detected, manual metadata should be provided. Consider the following example:
@ConfigurationProperties(prefix = "my.messaging")
public class MyMessagingProperties {
private List<String> addresses = new ArrayList<>(Arrays.asList("a", "b"));
private ContainerType containerType = ContainerType.SIMPLE;
public enum ContainerType {
SIMPLE, DIRECT
}
}
In order to document default values for properties in the class above, you could add the following content to the manual metadata of the module:
{"properties": [
{
"name": "my.messaging.addresses",
"defaultValue": ["a", "b"]
},
{
"name": "my.messaging.container-type",
"defaultValue": "simple"
}
]}
Only the name of the property is required to document additional metadata for existing properties.
|
Nested Properties
The annotation processor automatically considers inner classes as nested properties.
Rather than documenting the ip
and port
at the root of the namespace, we could create a sub-namespace for it.
Consider the updated example:
@ConfigurationProperties(prefix = "my.server")
public class MyServerProperties {
private String name;
private Host host;
public static class Host {
private String ip;
private int port;
}
}
The preceding example produces metadata information for my.server.name
, my.server.host.ip
, and my.server.host.port
properties.
You can use the @NestedConfigurationProperty
annotation on a field to indicate that a regular (non-inner) class should be treated as if it were nested.
This has no effect on collections and maps, as those types are automatically identified, and a single metadata property is generated for each of them. |
Adding Additional Metadata
Spring Boot’s configuration file handling is quite flexible, and it is often the case that properties may exist that are not bound to a @ConfigurationProperties
bean.
You may also need to tune some attributes of an existing key.
To support such cases and let you provide custom "hints", the annotation processor automatically merges items from META-INF/additional-spring-configuration-metadata.json
into the main metadata file.
If you refer to a property that has been detected automatically, the description, default value, and deprecation information are overridden, if specified. If the manual property declaration is not identified in the current module, it is added as a new property.
The format of the additional-spring-configuration-metadata.json
file is exactly the same as the regular spring-configuration-metadata.json
.
The additional properties file is optional.
If you do not have any additional properties, do not add the file.
Appendix C: Auto-configuration Classes
This appendix contains details of all of the auto-configuration classes provided by Spring Boot, with links to documentation and source code.
Remember to also look at the conditions report in your application for more details of which features are switched on.
(To do so, start the app with --debug
or -Ddebug
or, in an Actuator application, use the conditions
endpoint).
.C.1. spring-boot-autoconfigure
The following auto-configuration classes are from the spring-boot-autoconfigure
module:
Configuration Class | Links |
---|---|
Appendix D: Test Auto-configuration Annotations
This appendix describes the @…Test
auto-configuration annotations that Spring Boot provides to test slices of your application.
.D.1. Test Slices
The following table lists the various @…Test
annotations that can be used to test slices of your application and the auto-configuration that they import by default:
Test slice | Imported auto-configuration |
---|---|
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Appendix E: The Executable Jar Format
The spring-boot-loader
modules lets Spring Boot support executable jar and war files.
If you use the Maven plugin or the Gradle plugin, executable jars are automatically generated, and you generally do not need to know the details of how they work.
If you need to create executable jars from a different build system or if you are just curious about the underlying technology, this appendix provides some background.
.E.1. Nested JARs
Java does not provide any standard way to load nested jar files (that is, jar files that are themselves contained within a jar). This can be problematic if you need to distribute a self-contained application that can be run from the command line without unpacking.
To solve this problem, many developers use “shaded” jars. A shaded jar packages all classes, from all jars, into a single “uber jar”. The problem with shaded jars is that it becomes hard to see which libraries are actually in your application. It can also be problematic if the same filename is used (but with different content) in multiple jars. Spring Boot takes a different approach and lets you actually nest jars directly.
The Executable Jar File Structure
Spring Boot Loader-compatible jar files should be structured in the following way:
example.jar | +-META-INF | +-MANIFEST.MF +-org | +-springframework | +-boot | +-loader | +-<spring boot loader classes> +-BOOT-INF +-classes | +-mycompany | +-project | +-YourClasses.class +-lib +-dependency1.jar +-dependency2.jar
Application classes should be placed in a nested BOOT-INF/classes
directory.
Dependencies should be placed in a nested BOOT-INF/lib
directory.
The Executable War File Structure
Spring Boot Loader-compatible war files should be structured in the following way:
example.war | +-META-INF | +-MANIFEST.MF +-org | +-springframework | +-boot | +-loader | +-<spring boot loader classes> +-WEB-INF +-classes | +-com | +-mycompany | +-project | +-YourClasses.class +-lib | +-dependency1.jar | +-dependency2.jar +-lib-provided +-servlet-api.jar +-dependency3.jar
Dependencies should be placed in a nested WEB-INF/lib
directory.
Any dependencies that are required when running embedded but are not required when deploying to a traditional web container should be placed in WEB-INF/lib-provided
.
Index Files
Spring Boot Loader-compatible jar and war archives can include additional index files under the BOOT-INF/
directory.
A classpath.idx
file can be provided for both jars and wars, and it provides the ordering that jars should be added to the classpath.
The layers.idx
file can be used only for jars, and it allows a jar to be split into logical layers for Docker/OCI image creation.
Index files follow a YAML compatible syntax so that they can be easily parsed by third-party tools. These files, however, are not parsed internally as YAML and they must be written in exactly the formats described below in order to be used.
Classpath Index
The classpath index file can be provided in BOOT-INF/classpath.idx
.
Typically, it is generated automatically by Spring Boot’s Maven and Gradle build plugins.
It provides a list of jar names (including the directory) in the order that they should be added to the classpath.
When generated by the build plugins, this classpath ordering matches that used by the build system for running and testing the application.
Each line must start with dash space ("-·"
) and names must be in double quotes.
For example, given the following jar:
example.jar | +-META-INF | +-... +-BOOT-INF +-classes | +... +-lib +-dependency1.jar +-dependency2.jar
The index file would look like this:
- "BOOT-INF/lib/dependency2.jar" - "BOOT-INF/lib/dependency1.jar"
Layer Index
The layers index file can be provided in BOOT-INF/layers.idx
.
It provides a list of layers and the parts of the jar that should be contained within them.
Layers are written in the order that they should be added to the Docker/OCI image.
Layers names are written as quoted strings prefixed with dash space ("-·"
) and with a colon (":"
) suffix.
Layer content is either a file or directory name written as a quoted string prefixed by space space dash space ("··-·"
).
A directory name ends with /
, a file name does not.
When a directory name is used it means that all files inside that directory are in the same layer.
A typical example of a layers index would be:
- "dependencies": - "BOOT-INF/lib/dependency1.jar" - "BOOT-INF/lib/dependency2.jar" - "application": - "BOOT-INF/classes/" - "META-INF/"
.E.2. Spring Boot’s “NestedJarFile” Class
The core class used to support loading nested jars is org.springframework.boot.loader.jar.NestedJarFile
.
It lets you load jar content from nested child jar data.
When first loaded, the location of each JarEntry
is mapped to a physical file offset of the outer jar, as shown in the following example:
myapp.jar +-------------------+-------------------------+ | /BOOT-INF/classes | /BOOT-INF/lib/mylib.jar | |+-----------------+||+-----------+----------+| || A.class ||| B.class | C.class || |+-----------------+||+-----------+----------+| +-------------------+-------------------------+ ^ ^ ^ 0063 3452 3980
The preceding example shows how A.class
can be found in /BOOT-INF/classes
in myapp.jar
at position 0063
.
B.class
from the nested jar can actually be found in myapp.jar
at position 3452
, and C.class
is at position 3980
.
Armed with this information, we can load specific nested entries by seeking to the appropriate part of the outer jar. We do not need to unpack the archive, and we do not need to read all entry data into memory.
Compatibility With the Standard Java “JarFile”
Spring Boot Loader strives to remain compatible with existing code and libraries.
org.springframework.boot.loader.jar.NestedJarFile
extends from java.util.jar.JarFile
and should work as a drop-in replacement.
Nested JAR URLs of the form jar:nested:/path/myjar.jar/!BOOT-INF/lib/mylib.jar!/B.class
are supported and open a connection compatible with java.net.JarURLConnection
.
These can be used with Java’s URLClassLoader
.
.E.3. Launching Executable Jars
The org.springframework.boot.loader.launch.Launcher
class is a special bootstrap class that is used as an executable jar’s main entry point.
It is the actual Main-Class
in your jar file, and it is used to setup an appropriate ClassLoader
and ultimately call your main()
method.
There are three launcher subclasses (JarLauncher
, WarLauncher
, and PropertiesLauncher
).
Their purpose is to load resources (.class
files and so on) from nested jar files or war files in directories (as opposed to those explicitly on the classpath).
In the case of JarLauncher
and WarLauncher
, the nested paths are fixed.
JarLauncher
looks in BOOT-INF/lib/
, and WarLauncher
looks in WEB-INF/lib/
and WEB-INF/lib-provided/
.
You can add extra jars in those locations if you want more.
The PropertiesLauncher
looks in BOOT-INF/lib/
in your application archive by default.
You can add additional locations by setting an environment variable called LOADER_PATH
or loader.path
in loader.properties
(which is a comma-separated list of directories, archives, or directories within archives).
Launcher Manifest
You need to specify an appropriate Launcher
as the Main-Class
attribute of META-INF/MANIFEST.MF
.
The actual class that you want to launch (that is, the class that contains a main
method) should be specified in the Start-Class
attribute.
The following example shows a typical MANIFEST.MF
for an executable jar file:
Main-Class: org.springframework.boot.loader.launch.JarLauncher Start-Class: com.mycompany.project.MyApplication
For a war file, it would be as follows:
Main-Class: org.springframework.boot.loader.launch.WarLauncher Start-Class: com.mycompany.project.MyApplication
You need not specify Class-Path entries in your manifest file.
The classpath is deduced from the nested jars.
|
.E.4. PropertiesLauncher Features
PropertiesLauncher
has a few special features that can be enabled with external properties (System properties, environment variables, manifest entries, or loader.properties
).
The following table describes these properties:
Key | Purpose |
---|---|
|
Comma-separated Classpath, such as |
|
Used to resolve relative paths in |
|
Default arguments for the main method (space separated). |
|
Name of main class to launch (for example, |
|
Name of properties file (for example, |
|
Path to properties file (for example, |
|
Boolean flag to indicate that all properties should be added to System properties.
It defaults to |
When specified as environment variables or manifest entries, the following names should be used:
Key | Manifest entry | Environment variable |
---|---|---|
|
|
|
|
|
|
|
|
|
|
|
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|
|
|
Build plugins automatically move the Main-Class attribute to Start-Class when the uber jar is built.
If you use that, specify the name of the class to launch by using the Main-Class attribute and leaving out Start-Class .
|
The following rules apply to working with PropertiesLauncher
:
-
loader.properties
is searched for inloader.home
, then in the root of the classpath, and then inclasspath:/BOOT-INF/classes
. The first location where a file with that name exists is used. -
loader.home
is the directory location of an additional properties file (overriding the default) only whenloader.config.location
is not specified. -
loader.path
can contain directories (which are scanned recursively for jar and zip files), archive paths, a directory within an archive that is scanned for jar files (for example,dependencies.jar!/lib
), or wildcard patterns (for the default JVM behavior). Archive paths can be relative toloader.home
or anywhere in the file system with ajar:file:
prefix. -
loader.path
(if empty) defaults toBOOT-INF/lib
(meaning a local directory or a nested one if running from an archive). Because of this,PropertiesLauncher
behaves the same asJarLauncher
when no additional configuration is provided. -
loader.path
can not be used to configure the location ofloader.properties
(the classpath used to search for the latter is the JVM classpath whenPropertiesLauncher
is launched). -
Placeholder replacement is done from System and environment variables plus the properties file itself on all values before use.
-
The search order for properties (where it makes sense to look in more than one place) is environment variables, system properties,
loader.properties
, the exploded archive manifest, and the archive manifest.
.E.5. Executable Jar Restrictions
You need to consider the following restrictions when working with a Spring Boot Loader packaged application:
-
Zip entry compression: The
ZipEntry
for a nested jar must be saved by using theZipEntry.STORED
method. This is required so that we can seek directly to individual content within the nested jar. The content of the nested jar file itself can still be compressed, as can any other entries in the outer jar.
-
System classLoader: Launched applications should use
Thread.getContextClassLoader()
when loading classes (most libraries and frameworks do so by default). Trying to load nested jar classes withClassLoader.getSystemClassLoader()
fails.java.util.Logging
always uses the system classloader. For this reason, you should consider a different logging implementation.
Appendix F: Dependency Versions
This appendix provides details of the dependencies that are managed by Spring Boot.
.F.1. Managed Dependency Coordinates
The following table provides details of all of the dependency versions that are provided by Spring Boot in its CLI (Command Line Interface), Maven dependency management, and Gradle plugin. When you declare a dependency on one of these artifacts without declaring a version, the version listed in the table is used.
Group ID | Artifact ID | Version |
---|---|---|
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.F.2. Version Properties
The following table provides all properties that can be used to override the versions managed by Spring Boot.
Browse the spring-boot-dependencies
build.gradle for a complete list of dependencies.
You can learn how to customize these versions in your application in the Build Tool Plugins documentation.
Library | Version Property |
---|---|
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