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2.3.0.M2
Copyright © 2012-2020
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1. Spring Boot Documentation
This section provides a brief overview of Spring Boot reference documentation. It serves as a map for the rest of the document.
1.1. About the Documentation
The Spring Boot reference guide is available as:
The latest copy is available at docs.spring.io/spring-boot/docs/current/reference/.
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.
1.2. 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. |
1.3. First Steps
If you are getting started with Spring Boot or 'Spring' in general, start with the following topics:
-
From scratch: Overview | Requirements | Installation
1.4. Working 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
1.5. Learning about Spring Boot Features
Need more details about Spring Boot’s core features? The following content is for you:
-
Core Features: SpringApplication | External Configuration | Profiles | Logging
-
Web Applications: MVC | Embedded Containers
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Testing: Overview | Boot Applications | Utils
-
Extending: Auto-configuration | @Conditions
1.6. Moving to Production
When you are ready to push your Spring Boot application to production, we have some tricks that you might like:
1.7. 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
2. 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.
2.1. Introducing Spring Boot
Spring Boot makes it easy 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.
We also provide a command line tool that runs “spring scripts”.
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 and no requirement for XML configuration.
2.2. System Requirements
Spring Boot 2.3.0.M2 requires Java 8 and is compatible up to Java 13 (included). Spring Framework 5.2.3.RELEASE or above is also required.
Explicit build support is provided for the following build tools:
Build Tool | Version |
---|---|
Maven |
3.3+ |
Gradle |
6.x (5.6 is also supported but in a deprecated form) |
2.3. 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 v1.8 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.
2.3.1. 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 3.3 or above. 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
groupId
.
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.
The following listing shows a typical pom.xml
file:
<?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>
<!-- Inherit defaults from Spring Boot -->
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.0.M2</version>
</parent>
<!-- Override inherited settings -->
<description/>
<developers>
<developer/>
</developers>
<licenses>
<license/>
</licenses>
<scm>
<url/>
</scm>
<url/>
<!-- Add typical dependencies for a web application -->
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
<!-- Package as an executable jar -->
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<!-- Add Spring repositories -->
<!-- (you don't need this if you are using a .RELEASE 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 spring-boot-starter-parent is a great way to use Spring Boot, but it might not be suitable all of the time.
Sometimes you may need to inherit from a different parent POM, or you might not like our default settings.
In those cases, see Using Spring Boot without the Parent POM for an alternative solution that uses an import scope.
|
Gradle Installation
Spring Boot is compatible with 6.x. 5.6 is also supported but this support is deprecated and will be removed in a future release. 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.
2.3.2. 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. It lets you run Groovy scripts, which means that you have a familiar Java-like syntax without so much boilerplate code.
You do not need to use the CLI to work with Spring Boot, but it is definitely the quickest way to get a Spring application off the ground.
Manual Installation
You can download the Spring CLI distribution from the Spring software repository:
Cutting edge snapshot distributions are also available.
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 Boot v2.3.0.M2
If you develop features for the CLI and want easy 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-2.3.0.M2-bin/spring-2.3.0.M2/ $ sdk default springboot dev $ spring --version Spring CLI v2.3.0.M2
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 * 2.3.0.M2 ================================================================================ + - 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 pivotal/tap $ brew install springboot
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 /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.
|
Quick-start Spring CLI Example
You can use the following web application to test your installation.
To start, create a file called app.groovy
, as follows:
@RestController
class ThisWillActuallyRun {
@RequestMapping("/")
String home() {
"Hello World!"
}
}
Then run it from a shell, as follows:
$ spring run app.groovy
The first run of your application is slow, as dependencies are downloaded. Subsequent runs are much quicker. |
Open localhost:8080
in your favorite web browser.
You should see the following output:
Hello World!
2.3.3. Upgrading from an Earlier Version of Spring Boot
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.
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’re done with the migration, please make sure to remove this module from your project’s dependencies. |
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.
2.4. Developing Your First Spring Boot Application
This section describes how to develop a simple “Hello World!” web application that highlights some of Spring Boot’s key features. We use Maven to build this project, since most IDEs support it.
The spring.io web site 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 Spring Initializr documentation for more details. |
Before we begin, open a terminal and run the following commands to ensure that you have valid versions of Java and Maven installed:
$ java -version java version "1.8.0_102" Java(TM) SE Runtime Environment (build 1.8.0_102-b14) Java HotSpot(TM) 64-Bit Server VM (build 25.102-b14, mixed mode)
$ mvn -v Apache Maven 3.5.4 (1edded0938998edf8bf061f1ceb3cfdeccf443fe; 2018-06-17T14:33:14-04:00) Maven home: /usr/local/Cellar/maven/3.3.9/libexec Java version: 1.8.0_102, vendor: Oracle Corporation
This sample needs to be created in its own folder. Subsequent instructions assume that you have created a suitable folder and that it is your current directory. |
2.4.1. Creating the POM
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>2.3.0.M2</version>
</parent>
<description/>
<developers>
<developer/>
</developers>
<licenses>
<license/>
</licenses>
<scm>
<url/>
</scm>
<url/>
<!-- Additional lines to be added here... -->
<!-- (you don't need this if you are using a .RELEASE 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. |
2.4.2. Adding Classpath Dependencies
Spring Boot provides a number of “Starters” that let you add jars to your classpath.
Our applications for smoke tests 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.
Other “Starters” provide dependencies that you are likely to need when developing a specific type of application.
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.
2.4.3. Writing the Code
To finish our application, we need to create a single Java file.
By default, Maven compiles sources from src/main/java
, so you need to create that folder structure and then add a file named src/main/java/Example.java
to contain the following code:
import org.springframework.boot.*;
import org.springframework.boot.autoconfigure.*;
import org.springframework.web.bind.annotation.*;
@RestController
@EnableAutoConfiguration
public class Example {
@RequestMapping("/")
String home() {
return "Hello World!";
}
public static void main(String[] args) {
SpringApplication.run(Example.class, 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 Example
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 @EnableAutoConfiguration Annotation
The second class-level annotation is @EnableAutoConfiguration
.
This annotation 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 just 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 Example.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.
2.4.4. Running the Example
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 :: (v2.3.0.M2) ....... . . . ....... . . . (log output here) ....... . . . ........ Started Example in 2.222 seconds (JVM 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
.
2.4.5. 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 “fat jars”) are archives containing your compiled classes along with all of the jar dependencies that your code needs to run.
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:2.3.0.M2: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 10 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 :: (v2.3.0.M2) ....... . . . ....... . . . (log output here) ....... . . . ........ Started Example in 2.536 seconds (JVM running for 2.864)
As before, to exit the application, press ctrl-c
.
2.5. 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 check out 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 Using Spring Boot. If you are really impatient, you could also jump ahead and read about Spring Boot features.
3. Using 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.
3.1. 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.
3.1.1. 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 not specify its version. |
3.1.2. Maven
Maven users can inherit from the spring-boot-starter-parent
project to obtain sensible defaults.
The parent project provides the following features:
-
Java 1.8 as the default compiler level.
-
UTF-8 source encoding.
-
A Dependency Management section, inherited from the spring-boot-dependencies pom, that manages the versions of common dependencies. This dependency management lets you omit <version> tags for those dependencies when used in your own pom.
-
An execution of the
repackage
goal with arepackage
execution id. -
Sensible resource filtering.
-
Sensible plugin configuration (exec plugin, Git commit ID, and shade).
-
Sensible resource filtering for
application.properties
andapplication.yml
including profile-specific files (for example,application-dev.properties
andapplication-dev.yml
)
Note that, since the application.properties
and application.yml
files accept Spring style placeholders (${…}
), the Maven filtering is changed to use @..@
placeholders.
(You can override that by setting a Maven property called resource.delimiter
.)
Inheriting the Starter Parent
To configure your project to inherit from the spring-boot-starter-parent
, set the parent
as follows:
<!-- Inherit defaults from Spring Boot -->
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.0.M2</version>
</parent>
You should need to specify only the Spring Boot version number on this dependency. If you import additional starters, you can safely omit the version number. |
With that setup, you can also override individual dependencies by overriding a property in your own project.
For instance, to upgrade to another Spring Data release train, you would add the following to your pom.xml
:
<properties>
<spring-data-releasetrain.version>Fowler-SR2</spring-data-releasetrain.version>
</properties>
Check out the Customize Dependency Versions “How-to” for more information. |
Using Spring Boot without the Parent POM
Not everyone likes inheriting from the spring-boot-starter-parent
POM.
You may have your own corporate standard parent that you need to use or you may prefer to explicitly declare all your Maven configuration.
If you do not want to use the spring-boot-starter-parent
, you can still keep the benefit of the dependency management (but not the plugin management) by using a scope=import
dependency, as follows:
<dependencyManagement>
<dependencies>
<dependency>
<!-- Import dependency management from Spring Boot -->
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>2.3.0.M2</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
The preceding sample setup does not let you override individual dependencies by using a property, as explained above.
To achieve the same result, you need to add an entry in the dependencyManagement
of your project before the spring-boot-dependencies
entry.
For instance, to upgrade to another Spring Data release train, you could add the following element to your pom.xml
:
<dependencyManagement>
<dependencies>
<!-- Override Spring Data release train provided by Spring Boot -->
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-releasetrain</artifactId>
<version>Fowler-SR2</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>2.3.0.M2</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
In the preceding example, we specify a BOM, but any dependency type can be overridden in the same way. |
Using the Spring Boot Maven Plugin
Spring Boot includes a Maven plugin that can package the project as an executable jar.
Add the plugin to your <plugins>
section if you want to use it, as shown in the following example:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
If you use the Spring Boot starter parent pom, you need to add only the plugin. There is no need to configure it unless you want to change the settings defined in the parent. |
3.1.3. Gradle
To learn about using Spring Boot with Gradle, please refer to the documentation for Spring Boot’s Gradle plugin:
3.1.4. 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="2.3.0.M2" />
<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” .
|
3.1.5. 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 |
|
Starter for JMS messaging using Apache ActiveMQ |
|
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 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 |
|
Starter for using the Apache Solr search platform with Spring Data Solr |
|
Starter for building MVC web applications using FreeMarker views |
|
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. An alternative to |
|
Starter for reading and writing json |
|
Starter for JTA transactions using Atomikos |
|
Starter for JTA transactions using Bitronix |
|
Starter for using Java Mail and Spring Framework’s email sending support |
|
Starter for building web applications using Mustache views |
|
Starter for using Spring Security’s OAuth2/OpenID Connect client features |
|
Starter for using Spring Security’s OAuth2 resource server features |
|
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, Hamcrest and Mockito |
|
Starter for building MVC web applications using Thymeleaf views |
|
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 |
|
Starter for building WebSocket applications using Spring Framework’s 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 |
|
Starter for using Undertow as the embedded servlet container. An alternative to |
For a list of additional community contributed starters, see the README file in the spring-boot-starters module on GitHub.
|
3.2. Structuring Your Code
Spring Boot does not require any specific code layout to work. However, there are some best practices that help.
3.2.1. 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 ).
|
3.2.2. 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 don’t want to use @SpringBootApplication , the @EnableAutoConfiguration and @ComponentScan annotations that it imports defines that behaviour so you can also use those instead.
|
The following listing shows a typical layout:
com +- example +- myapplication +- Application.java | +- customer | +- Customer.java | +- CustomerController.java | +- CustomerService.java | +- CustomerRepository.java | +- order +- Order.java +- OrderController.java +- OrderService.java +- OrderRepository.java
The Application.java
file would declare the main
method, along with the basic @SpringBootApplication
, as follows:
package com.example.myapplication;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
3.3. 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.
|
3.3.1. 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.
3.4. 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.
|
3.4.1. 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.
3.4.2. 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:
import org.springframework.boot.autoconfigure.*;
import org.springframework.boot.autoconfigure.jdbc.*;
@SpringBootApplication(exclude={DataSourceAutoConfiguration.class})
public 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.
|
3.5. 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.
For simplicity, we often find that using @ComponentScan
(to find your beans) and using @Autowired
(to do constructor injection) works well.
If you structure your code as suggested above (locating your application class in a root package), you can add @ComponentScan
without any arguments.
All of your application components (@Component
, @Service
, @Repository
, @Controller
etc.) are automatically registered as Spring Beans.
The following example shows a @Service
Bean that uses constructor injection to obtain a required RiskAssessor
bean:
package com.example.service;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class DatabaseAccountService implements AccountService {
private final RiskAssessor riskAssessor;
@Autowired
public DatabaseAccountService(RiskAssessor riskAssessor) {
this.riskAssessor = riskAssessor;
}
// ...
}
If a bean has one constructor, you can omit the @Autowired
, as shown in the following example:
@Service
public class DatabaseAccountService implements AccountService {
private final RiskAssessor riskAssessor;
public DatabaseAccountService(RiskAssessor riskAssessor) {
this.riskAssessor = riskAssessor;
}
// ...
}
Notice how using constructor injection lets the riskAssessor field be marked as final , indicating that it cannot be subsequently changed.
|
3.6. 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) -
@Configuration
: allow to register extra beans in the context or import additional configuration classes
package com.example.myapplication;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication // same as @Configuration @EnableAutoConfiguration @ComponentScan
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
@SpringBootApplication also provides aliases to customize the attributes of @EnableAutoConfiguration and @ComponentScan .
|
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:
In this example, |
3.7. 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. Debugging Spring Boot applications is also easy. 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, you should refer to your server and IDE documentation. |
3.7.1. Running from an IDE
You can run a Spring Boot application from your IDE as a simple 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.
STS users can use the Relaunch button rather than the Run button to ensure that any existing instance is closed.
|
3.7.2. 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
3.7.3. 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
3.7.4. 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
3.7.5. Hot Swapping
Since Spring Boot applications are just 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 Developer Tools section later in this chapter and the Hot swapping “How-to” for details.
3.8. 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>
configurations {
developmentOnly
runtimeClasspath {
extendsFrom developmentOnly
}
}
dependencies {
developmentOnly("org.springframework.boot:spring-boot-devtools")
}
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”.
If that does not apply to you (i.e. if you run your application from a container), consider excluding devtools or set the -Dspring.devtools.restart.enabled=false system property.
|
Flagging the dependency as optional in Maven or using a custom developmentOnly configuration in Gradle (as shown above) is a best practice that 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 disable the excludeDevtools build property to include it.
The property is supported with both the Maven and Gradle plugins.
|
3.8.1. 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.
Because you need more information about web requests while developing Spring MVC and Spring WebFlux applications, developer tools will 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, etc.
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.
If you don’t want property defaults to be applied you can set spring.devtools.add-properties to false in your application.properties .
|
For a complete list of the properties that are applied by the devtools, see DevToolsPropertyDefaultsPostProcessor. |
3.8.2. 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 folder is monitored for changes.
Note that certain resources, such as static assets and view templates, do not need to restart the application.
As long as forking is enabled, you can also start your application by using the supported build plugins (Maven and Gradle), since DevTools needs an isolated application classloader to operate properly. By default, the Gradle and Maven plugins fork the application process. |
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) ).
|
When deciding if an entry on the classpath should trigger a restart when it changes, DevTools automatically ignores projects named spring-boot , spring-boot-devtools , spring-boot-autoconfigure , spring-boot-actuator , and spring-boot-starter .
|
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.
|
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
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/**
If you want to keep those defaults and add additional exclusions, use the spring.devtools.restart.additional-exclude property instead.
|
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:
public static void main(String[] args) {
System.setProperty("spring.devtools.restart.enabled", "false");
SpringApplication.run(MyApp.class, 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
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, 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. For most applications, this approach works well. However, it can sometimes cause classloading issues.
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.
If you work on a multi-module project, and not every module is imported into your IDE, you may need to customize things.
To do so, you can create 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
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.
3.8.3. 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 from livereload.com.
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. |
3.8.4. Global Settings
You can configure global devtools settings by adding any of the following files to the $HOME/.config/spring-boot
folder:
-
spring-boot-devtools.properties
-
spring-boot-devtools.yaml
-
spring-boot-devtools.yml
Any properties added to these file 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:
spring.devtools.restart.trigger-file=.reloadtrigger
If devtools configuration files are not found in $HOME/.config/spring-boot , the root of the $HOME folder 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 activated in the above files will not affect the loading of profile-specific configuration files. |
3.8.5. 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.
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 STS 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 :: 2.3.0.M2 2015-06-10 18:25:06.632 INFO 14938 --- [ main] o.s.b.devtools.RemoteSpringApplication : Starting RemoteSpringApplication on pwmbp with PID 14938 (/Users/pwebb/projects/spring-boot/code/spring-boot-project/spring-boot-devtools/target/classes started by pwebb in /Users/pwebb/projects/spring-boot/code) 2015-06-10 18:25:06.671 INFO 14938 --- [ main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@2a17b7b6: startup date [Wed Jun 10 18:25:06 PDT 2015]; root of context hierarchy 2015-06-10 18:25:07.043 WARN 14938 --- [ main] o.s.b.d.r.c.RemoteClientConfiguration : The connection to http://localhost:8080 is insecure. You should use a URL starting with 'https://'. 2015-06-10 18:25:07.074 INFO 14938 --- [ main] o.s.b.d.a.OptionalLiveReloadServer : LiveReload server is running on port 35729 2015-06-10 18:25:07.130 INFO 14938 --- [ main] o.s.b.devtools.RemoteSpringApplication : Started RemoteSpringApplication in 0.74 seconds (JVM running for 1.105)
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.
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. |
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. The changes are then uploaded to the remote application. 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:
spring.devtools.restart.poll-interval=2s
spring.devtools.restart.quiet-period=1s
The monitored classpath folders 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.
3.9. 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 Spring Boot Actuator: Production-ready Features for details.
3.10. 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.
4. Spring Boot 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 "Using Spring Boot" sections, so that you have a good grounding of the basics.
4.1. 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:
public static void main(String[] args) {
SpringApplication.run(MySpringConfiguration.class, args);
}
When your application starts, you should see something similar to the following output:
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: v2.3.0.M2 2019-04-31 13:09:54.117 INFO 56603 --- [ main] o.s.b.s.app.SampleApplication : Starting SampleApplication v0.1.0 on mycomputer with PID 56603 (/apps/myapp.jar started by pwebb) 2019-04-31 13:09:54.166 INFO 56603 --- [ main] ationConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6e5a8246: startup date [Wed Jul 31 00:08:16 PDT 2013]; root of context hierarchy 2019-04-01 13:09:56.912 INFO 41370 --- [ main] .t.TomcatServletWebServerFactory : Server initialized with port: 8080 2019-04-01 13:09:57.501 INFO 41370 --- [ main] o.s.b.s.app.SampleApplication : Started SampleApplication in 2.992 seconds (JVM running for 3.658)
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 .
|
4.1.1. 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's 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
4.1.2. 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 programatically 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
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.
|
4.1.3. 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
.
In addition to a text file, you can also add a banner.gif
, banner.jpg
, or banner.png
image file to your classpath or set the spring.banner.image.location
property.
Images are converted into an ASCII art representation and printed above any text banner.
Inside your banner.txt
file, you can use 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
.
4.1.4. 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:
public static void main(String[] args) {
SpringApplication app = new SpringApplication(MySpringConfiguration.class);
app.setBannerMode(Banner.Mode.OFF);
app.run(args);
}
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 references to XML configuration or to packages that should be scanned.
|
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.
4.1.5. 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);
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.
|
4.1.6. 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
ApplicationReadyEvent
is sent after any application and command-line runners have been called. It indicates 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
ContextRefreshedEvent
is sent when anApplicationContext
is refreshed. -
A
WebServerInitializedEvent
is sent after theWebServer
is ready.ServletWebServerInitializedEvent
andReactiveWebServerInitializedEvent
are the servlet and reactive variants respectively.
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. |
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
.
4.1.7. Web Environment
A SpringApplication
attempts to create the right type of ApplicationContext
on your behalf.
The algorithm used to determine a WebApplicationType
is fairly simple:
-
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 setApplicationContextClass(…)
.
It is often desirable to call setWebApplicationType(WebApplicationType.NONE) when using SpringApplication within a JUnit test.
|
4.1.8. 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:
import org.springframework.boot.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.stereotype.*;
@Component
public class MyBean {
@Autowired
public MyBean(ApplicationArguments args) {
boolean debug = args.containsOption("debug");
List<String> files = args.getNonOptionArgs();
// if run with "--debug logfile.txt" debug=true, files=["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.
|
4.1.9. 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.
The CommandLineRunner
interfaces provides access to application arguments as a simple string array, whereas the ApplicationRunner
uses the ApplicationArguments
interface discussed earlier.
The following example shows a CommandLineRunner
with a run
method:
import org.springframework.boot.*;
import org.springframework.stereotype.*;
@Component
public class MyBean implements CommandLineRunner {
public void run(String... args) {
// 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.
4.1.10. 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 ExitCodeApplication {
@Bean
public ExitCodeGenerator exitCodeGenerator() {
return () -> 42;
}
public static void main(String[] args) {
System.exit(SpringApplication.exit(SpringApplication.run(ExitCodeApplication.class, 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.
4.1.11. 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 .
|
4.2. 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 properties files, YAML files, environment variables, and command-line arguments to externalize configuration.
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.
Properties are considered in the following order:
-
Devtools global settings properties in the
$HOME/.config/spring-boot
folder when devtools is active. -
@TestPropertySource
annotations on your tests. -
properties
attribute on your tests. Available on@SpringBootTest
and the test annotations for testing a particular slice of your application. -
Command line arguments.
-
Properties from
SPRING_APPLICATION_JSON
(inline JSON embedded in an environment variable or system property). -
ServletConfig
init parameters. -
ServletContext
init parameters. -
JNDI attributes from
java:comp/env
. -
Java System properties (
System.getProperties()
). -
OS environment variables.
-
A
RandomValuePropertySource
that has properties only inrandom.*
. -
Profile-specific application properties outside of your packaged jar (
application-{profile}.properties
and YAML variants). -
Profile-specific application properties packaged inside your jar (
application-{profile}.properties
and YAML variants). -
Application properties outside of your packaged jar (
application.properties
and YAML variants). -
Application properties packaged inside your jar (
application.properties
and YAML variants). -
@PropertySource
annotations on your@Configuration
classes. Please note that such property sources are not added to theEnvironment
until the application context is being refreshed. This is too late to configure certain properties such aslogging.*
andspring.main.*
which are read before refresh begins. -
Default properties (specified by setting
SpringApplication.setDefaultProperties
).
To provide a concrete example, suppose you develop a @Component
that uses a name
property, as shown in the following example:
import org.springframework.stereotype.*;
import org.springframework.beans.factory.annotation.*;
@Component
public class MyBean {
@Value("${name}")
private String name;
// ...
}
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"
).
Spring Boot also supports wildcard locations when loading configuration files.
By default, a wildcard location of config/*/
outside of your jar is supported.
Wildcard locations are also supported when specifying spring.config.additional-location
and spring.config.location
.
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
that the app can bind to.
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.
Locations with wildcards are not processed in a deterministic order and files that match the wildcard cannot be used to override keys in the other. |
The $ SPRING_APPLICATION_JSON='{"acme":{"name":"test"}}' java -jar myapp.jar In the preceding example, you end up with $ java -Dspring.application.json='{"name":"test"}' -jar myapp.jar You can also supply the JSON by using a command line argument, as shown in the following example: $ java -jar myapp.jar --spring.application.json='{"name":"test"}' You can also supply the JSON as a JNDI variable, as follows: |
4.2.1. 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]}
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).
4.2.2. 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 other 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)
.
4.2.3. Application Property Files
SpringApplication
loads properties from application.properties
files in the following locations and adds them to the Spring Environment
:
-
A
/config
subdirectory of the current directory -
The current directory
-
A classpath
/config
package -
The classpath root
The list is ordered by precedence (properties defined in locations higher in the list override those defined in lower locations).
You can also use YAML ('.yml') files as an alternative to '.properties'. |
If you do not like application.properties
as the configuration file name, you can switch to another file name by specifying a spring.config.name
environment property.
You can also refer to an explicit location by using the spring.config.location
environment property (which is a comma-separated list of directory locations or file paths).
The following example shows how to specify a different file name:
$ java -jar myproject.jar --spring.config.name=myproject
The following example shows how to specify two locations:
$ java -jar myproject.jar --spring.config.location=classpath:/default.properties,classpath:/override.properties
spring.config.name and spring.config.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 /
(and, at runtime, be appended with the names generated from spring.config.name
before being loaded, including profile-specific file names).
Files specified in spring.config.location
are used as-is, with no support for profile-specific variants, and are overridden by any profile-specific properties.
Config locations are searched in reverse order.
By default, the configured locations are classpath:/,classpath:/config/,file:./,file:./config/*/,file:./config/
.
The resulting search order is the following:
-
file:./config/
-
file:./config/*/
-
file:./
-
classpath:/config/
-
classpath:/
When custom config locations are configured by using spring.config.location
, they replace the default locations.
For example, if spring.config.location
is configured with the value classpath:/custom-config/,file:./custom-config/
, the search order becomes the following:
-
file:./custom-config/
-
classpath:custom-config/
Alternatively, when custom config locations are configured by using spring.config.additional-location
, they are used in addition to the default locations.
Additional locations are searched before the default locations.
For example, if additional locations of classpath:/custom-config/,file:./custom-config/
are configured, the search order becomes the following:
-
file:./custom-config/
-
classpath:custom-config/
-
file:./config/
-
file:./config/*/
-
file:./
-
classpath:/config/
-
classpath:/
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.
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 ).
|
If your application runs in a container, 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.
|
4.2.4. Profile-specific Properties
In addition to application.properties
files, profile-specific properties can also be defined by using the following naming convention: application-{profile}.properties
.
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.properties
are loaded.
Profile-specific properties are loaded from the same locations as standard application.properties
, with profile-specific files always overriding the non-specific ones, whether or not the profile-specific files are inside or outside your packaged jar.
If several profiles are specified, a last-wins strategy applies.
For example, profiles specified by the spring.profiles.active
property are added after those configured through the SpringApplication
API and therefore take precedence.
If you have specified any files in spring.config.location , profile-specific variants of those files are not considered.
Use directories in spring.config.location if you want to also use profile-specific properties.
|
4.2.5. Placeholders in Properties
The values in application.properties
are filtered through the existing Environment
when they are used, so you can refer back to previously defined values (for example, from System properties).
app.name=MyApp
app.description=${app.name} is a Spring Boot application
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. |
4.2.6. 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’re looking for a secure way to store credentials and passwords, the Spring Cloud Vault project provides support for storing externalized configuration in HashiCorp Vault.
4.2.7. Using YAML Instead of Properties
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 .
|
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
.
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
The preceding example would be transformed into the following properties:
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
YAML lists 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
To bind to properties like that by using Spring Boot’s Binder
utilities (which is what @ConfigurationProperties
does), you need to have a property in the target bean of type java.util.List
(or Set
) and you either need to provide a setter or initialize it with a mutable value.
For example, the following example binds to the properties shown previously:
@ConfigurationProperties(prefix="my")
public class Config {
private List<String> servers = new ArrayList<String>();
public List<String> getServers() {
return this.servers;
}
}
Exposing YAML as Properties in the Spring Environment
The YamlPropertySourceLoader
class can be used to expose YAML as a PropertySource
in the Spring Environment
.
Doing so lets you use the @Value
annotation with placeholders syntax to access YAML properties.
Multi-profile YAML Documents
You can specify multiple profile-specific YAML documents in a single file by using a spring.profiles
key to indicate when the document applies, as shown in the following example:
server:
address: 192.168.1.100
---
spring:
profiles: development
server:
address: 127.0.0.1
---
spring:
profiles: production & eu-central
server:
address: 192.168.1.120
In the preceding example, if the development
profile is active, the server.address
property is 127.0.0.1
.
Similarly, if the production
and eu-central
profiles are active, the server.address
property is 192.168.1.120
.
If the development
, production
and eu-central
profiles are not enabled, then the value for the property is 192.168.1.100
.
|
If none are explicitly active when the application context starts, the default profiles are activated.
So, in the following YAML, we set a value for spring.security.user.password
that is available only in the "default" profile:
server:
port: 8000
---
spring:
profiles: default
security:
user:
password: weak
Whereas, in the following example, the password is always set because it is not attached to any profile, and it would have to be explicitly reset in all other profiles as necessary:
server:
port: 8000
spring:
security:
user:
password: weak
Spring profiles designated by using the spring.profiles
element may optionally be negated by using the !
character.
If both negated and non-negated profiles are specified for a single document, at least one non-negated profile must match, and no negated profiles may match.
YAML Shortcomings
YAML files cannot be loaded by using the @PropertySource
annotation.
So, in the case that you need to load values that way, you need to use a properties file.
Using the multi YAML document syntax in profile-specific YAML files can lead to unexpected behavior. For example, consider the following config in a file:
server:
port: 8000
---
spring:
profiles: "!test"
security:
user:
password: "secret"
If you run the application with the argument --spring.profiles.active=dev
you might expect security.user.password
to be set to “secret”, but this is not the case.
The nested document will be filtered because the main file is named application-dev.yml
.
It is already considered to be profile-specific, and nested documents will be ignored.
We recommend that you don’t mix profile-specific YAML files and multiple YAML documents. Stick to using only one of them. |
4.2.8. 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:
package com.example;
import java.net.InetAddress;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.springframework.boot.context.properties.ConfigurationProperties;
@ConfigurationProperties("acme")
public class AcmeProperties {
private boolean enabled;
private InetAddress remoteAddress;
private final Security security = new Security();
public boolean isEnabled() { ... }
public void setEnabled(boolean enabled) { ... }
public InetAddress getRemoteAddress() { ... }
public void setRemoteAddress(InetAddress remoteAddress) { ... }
public Security getSecurity() { ... }
public static class Security {
private String username;
private String password;
private List<String> roles = new ArrayList<>(Collections.singleton("USER"));
public String getUsername() { ... }
public void setUsername(String username) { ... }
public String getPassword() { ... }
public void setPassword(String password) { ... }
public List<String> getRoles() { ... }
public void setRoles(List<String> roles) { ... }
}
}
The preceding POJO defines the following properties:
-
acme.enabled
, with a value offalse
by default. -
acme.remote-address
, with a type that can be coerced fromString
. -
acme.security.username
, with a nested "security" object whose name is determined by the name of the property. In particular, the return type is not used at all there and could have beenSecurityProperties
. -
acme.security.password
. -
acme.security.roles
, with a collection ofString
that defaults toUSER
.
The properties that map to @ConfigurationProperties classes available in Spring Boot, which are configured via properties files, YAML files, environment variables etc., 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:
package com.example;
import java.net.InetAddress;
import java.util.List;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.ConstructorBinding;
import org.springframework.boot.context.properties.DefaultValue;
@ConstructorBinding
@ConfigurationProperties("acme")
public class AcmeProperties {
private final boolean enabled;
private final InetAddress remoteAddress;
private final Security security;
public AcmeProperties(boolean enabled, InetAddress remoteAddress, Security security) {
this.enabled = enabled;
this.remoteAddress = remoteAddress;
this.security = security;
}
public boolean isEnabled() { ... }
public InetAddress getRemoteAddress() { ... }
public Security getSecurity() { ... }
public static class Security {
private final String username;
private final String password;
private final List<String> roles;
public Security(String username, String password,
@DefaultValue("USER") List<String> roles) {
this.username = username;
this.password = password;
this.roles = roles;
}
public String getUsername() { ... }
public String getPassword() { ... }
public List<String> getRoles() { ... }
}
}
In this setup, the @ConstructorBinding
annotation is used to indicate that constructor binding should be used.
This means that the binder will expect to find a constructor with the parameters that you wish to have bound.
Nested members of a @ConstructorBinding
class (such as Security
in the example above) will also be bound via their constructor.
Default values can be specified using @DefaultValue
and the same conversion service will be applied to coerce the String
value to the target type of a missing property.
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 (e.g. @Component beans, beans created via @Bean methods or beans loaded using @Import )
|
If you have more than one constructor for your class you can also use @ConstructorBinding directly on the constructor that should 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(AcmeProperties.class)
public class MyConfiguration {
}
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", "org.acme.another" })
public class MyApplication {
}
When the The bean name in the example above is |
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:
# application.yml
acme:
remote-address: 192.168.1.1
security:
username: admin
roles:
- USER
- ADMIN
# additional configuration as required
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 AcmeProperties properties;
@Autowired
public MyService(AcmeProperties properties) {
this.properties = properties;
}
//...
@PostConstruct
public void openConnection() {
Server server = new Server(this.properties.getRemoteAddress());
// ...
}
}
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:
@ConfigurationProperties(prefix = "another")
@Bean
public AnotherComponent anotherComponent() {
...
}
Any JavaBean property defined with the another
prefix is mapped onto that AnotherComponent
bean in manner similar to the preceding AcmeProperties
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="acme.my-project.person")
public class OwnerProperties {
private String firstName;
public String getFirstName() {
return this.firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
}
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 acme.my-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.
|
Numeric values surrounded by underscores, such as |
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.property-name=acme .
|
When binding to Map
properties, if the key
contains anything other than lowercase alpha-numeric characters or -
, you need to use the bracket notation so that the original 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
:
acme:
map:
"[/key1]": value1
"[/key2]": value2
/key3: value3
The properties above will bind to a Map
with /key1
, /key2
and key3
as the keys in the map.
For YAML files, the brackets need to be surrounded by quotes for the keys to be parsed properly. |
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 AcmeProperties
:
@ConfigurationProperties("acme")
public class AcmeProperties {
private final List<MyPojo> list = new ArrayList<>();
public List<MyPojo> getList() {
return this.list;
}
}
Consider the following configuration:
acme:
list:
- name: my name
description: my description
---
spring:
profiles: dev
acme:
list:
- name: my another name
If the dev
profile is not active, AcmeProperties.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:
acme:
list:
- name: my name
description: my description
- name: another name
description: another description
---
spring:
profiles: dev
acme:
list:
- name: my another name
In the preceding example, if the dev
profile is active, AcmeProperties.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 AcmeProperties
:
@ConfigurationProperties("acme")
public class AcmeProperties {
private final Map<String, MyPojo> map = new HashMap<>();
public Map<String, MyPojo> getMap() {
return this.map;
}
}
Consider the following configuration:
acme:
map:
key1:
name: my name 1
description: my description 1
---
spring:
profiles: dev
acme:
map:
key1:
name: dev name 1
key2:
name: dev name 2
description: dev description 2
If the dev
profile is not active, AcmeProperties.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 YAML 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 (e.g.
10s
means 10 seconds)
Consider the following example:
@ConfigurationProperties("app.system")
public class AppSystemProperties {
@DurationUnit(ChronoUnit.SECONDS)
private Duration sessionTimeout = Duration.ofSeconds(30);
private Duration readTimeout = Duration.ofMillis(1000);
public Duration getSessionTimeout() {
return this.sessionTimeout;
}
public void setSessionTimeout(Duration sessionTimeout) {
this.sessionTimeout = sessionTimeout;
}
public Duration getReadTimeout() {
return this.readTimeout;
}
public void setReadTimeout(Duration readTimeout) {
this.readTimeout = readTimeout;
}
}
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 are upgrading from a previous version that is simply using Long to express the duration, make sure to define the unit (using @DurationUnit ) if it isn’t milliseconds alongside the switch to Duration .
Doing so gives a transparent upgrade path while supporting a much richer format.
|
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 (e.g.
10MB
means 10 megabytes)
Consider the following example:
@ConfigurationProperties("app.io")
public class AppIoProperties {
@DataSizeUnit(DataUnit.MEGABYTES)
private DataSize bufferSize = DataSize.ofMegabytes(2);
private DataSize sizeThreshold = DataSize.ofBytes(512);
public DataSize getBufferSize() {
return this.bufferSize;
}
public void setBufferSize(DataSize bufferSize) {
this.bufferSize = bufferSize;
}
public DataSize getSizeThreshold() {
return this.sizeThreshold;
}
public void setSizeThreshold(DataSize sizeThreshold) {
this.sizeThreshold = sizeThreshold;
}
}
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 are upgrading from a previous version that is simply using Long to express the size, make sure to define the unit (using @DataSizeUnit ) if it isn’t bytes alongsidethe switch to DataSize .
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 javax.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(prefix="acme")
@Validated
public class AcmeProperties {
@NotNull
private InetAddress remoteAddress;
// ... getters and setters
}
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 AcmeProperties
example:
@ConfigurationProperties(prefix="acme")
@Validated
public class AcmeProperties {
@NotNull
private InetAddress remoteAddress;
@Valid
private final Security security = new Security();
// ... getters and setters
public static class Security {
@NotEmpty
public String username;
// ... getters and setters
}
}
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 |
No |
|
Yes |
No |
|
|
No |
Yes |
If you define a set of configuration keys for your own components, we recommend you group them in a POJO annotated with @ConfigurationProperties
.
You should also be aware that, since @Value
does not support relaxed binding, it is not a good candidate if you need to provide the value by using environment variables.
Finally, while you can write a SpEL
expression in @Value
, such expressions are not processed from application property files.
4.3. 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 {
// ...
}
If @ConfigurationProperties beans are registered via @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
You could also specify it on the command line by using the following switch: --spring.profiles.active=dev,hsqldb
.
4.3.1. 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 profil-specific properties that add to the active profiles rather than replace them.
The spring.profiles.include
property can be used to unconditionally add active profiles.
The SpringApplication
entry point also has a Java API for setting additional profiles (that is, on top of those activated by the spring.profiles.active
property).
See the setAdditionalProfiles()
method in SpringApplication.
For example, when an application with the following properties is run by using the switch, --spring.profiles.active=prod
, the proddb
and prodmq
profiles are also activated:
---
my.property: fromyamlfile
---
spring.profiles: prod
spring.profiles.include:
- proddb
- prodmq
Remember that the spring.profiles property can be defined in a YAML document to determine when this particular document is included in the configuration.
See Change Configuration Depending on the Environment for more details.
|
4.3.2. 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.
4.3.3. Profile-specific Configuration Files
Profile-specific variants of both application.properties
(or application.yml
) and files referenced through @ConfigurationProperties
are considered as files and loaded.
See "Profile-specific Properties" for details.
4.4. 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 via 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. |
4.4.1. Log Format
The default log output from Spring Boot resembles the following example:
2019-03-05 10:57:51.112 INFO 45469 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/7.0.52 2019-03-05 10:57:51.253 INFO 45469 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2019-03-05 10:57:51.253 INFO 45469 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1358 ms 2019-03-05 10:57:51.698 INFO 45469 --- [ost-startStop-1] o.s.b.c.e.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/] 2019-03-05 10:57:51.702 INFO 45469 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
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. -
Thread name: Enclosed in square brackets (may be truncated for console output).
-
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 .
|
4.4.2. 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 HH:mm:ss.SSS}){yellow}
The following colors and styles are supported:
-
blue
-
cyan
-
faint
-
green
-
magenta
-
red
-
yellow
4.4.3. 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.
Size limits can be changed using the logging.file.max-size
property.
Rotated log files of the last 7 days are kept by default unless the logging.file.max-history
property has been set.
The total size of log archives can be capped using logging.file.total-size-cap
.
When the total size of log archives exceeds that threshold, backups will be deleted.
To force log archive cleanup on application startup, use the logging.file.clean-history-on-start
property.
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.
|
4.4.4. 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
It’s 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’s 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.
|
4.4.5. Log Groups
It’s 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’t easily remember top level packages.
To help with this, Spring Boot allows you to define logging groups in your Spring Environment
.
For example, here’s 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
Once defined, you can change the level for all the loggers in the group with a single line:
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 |
|
4.4.6. 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 via 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, as described in the following table:
Spring Environment | System Property | Comments |
---|---|---|
|
|
The conversion word used when logging exceptions. |
|
|
Whether to clean the archive log files on startup (if LOG_FILE enabled). (Only supported with the default Logback setup.) |
|
|
If defined, it is used in the default log configuration. |
|
|
Maximum log file size (if LOG_FILE enabled). (Only supported with the default Logback setup.) |
|
|
Maximum number of archive log files to keep (if LOG_FILE enabled). (Only supported with the default Logback setup.) |
|
|
If defined, it is used in the default log configuration. |
|
|
Total size of log backups to be kept (if LOG_FILE enabled). (Only supported with the default Logback setup.) |
|
|
The log pattern to use on the console (stdout). (Only supported with the default Logback setup.) |
|
|
Appender pattern for log date format. (Only supported with the default Logback setup.) |
|
|
The log pattern to use in a file (if |
|
|
The format to use when rendering the log level (default |
|
|
Pattern for rolled-over log file names (default |
|
|
The current process ID (discovered if possible and when not already defined as an OS environment variable). |
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 |
4.4.7. 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 simple 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 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.
|
4.5. 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 (i.e. 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 supports comma-separated list of locations, either a package qualifier or a resource resolved from the classpath root.
|
See MessageSourceProperties
for more supported options.
4.6. JSON
Spring Boot provides integration with three JSON mapping libraries:
-
Gson
-
Jackson
-
JSON-B
Jackson is the preferred and default library.
4.6.1. 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
.
4.7. Developing Web Applications
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.
4.7.1. The “Spring Web MVC Framework”
The Spring Web MVC framework (often referred to as simply “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(value="/users")
public class MyRestController {
@RequestMapping(value="/{user}", method=RequestMethod.GET)
public User getUser(@PathVariable Long user) {
// ...
}
@RequestMapping(value="/{user}/customers", method=RequestMethod.GET)
List<Customer> getUserCustomers(@PathVariable Long user) {
// ...
}
@RequestMapping(value="/{user}", method=RequestMethod.DELETE)
public User deleteUser(@PathVariable Long user) {
// ...
}
}
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.
Spring MVC Auto-configuration
Spring Boot provides auto-configuration for Spring MVC that works well with most applications.
The auto-configuration adds the following features on top of Spring’s defaults:
-
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. -
Custom
Favicon
support (covered later in this document). -
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.
If you want to take complete control of Spring MVC, you can add your own @Configuration
annotated with @EnableWebMvc
, or alternatively add your own @Configuration
-annotated DelegatingWebMvcConfiguration
as described in the Javadoc of @EnableWebMvc
.
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:
import org.springframework.boot.autoconfigure.http.HttpMessageConverters;
import org.springframework.context.annotation.*;
import org.springframework.http.converter.*;
@Configuration(proxyBeanMethods = false)
public class MyConfiguration {
@Bean
public HttpMessageConverters customConverters() {
HttpMessageConverter<?> additional = ...
HttpMessageConverter<?> another = ...
return new 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.
Custom JSON 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:
import java.io.*;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import org.springframework.boot.jackson.*;
@JsonComponent
public class Example {
public static class Serializer extends JsonSerializer<SomeObject> {
// ...
}
public static class Deserializer extends JsonDeserializer<SomeObject> {
// ...
}
}
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.
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 also enabled and 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/**
You can also customize the static resource locations by using the spring.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.
Any resources with a path in /webjars/**
are served from jar files if they are packaged in the Webjars format.
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.resources.chain.strategy.content.enabled=true
spring.resources.chain.strategy.content.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.resources.chain.strategy.content.enabled=true
spring.resources.chain.strategy.content.paths=/**
spring.resources.chain.strategy.fixed.enabled=true
spring.resources.chain.strategy.fixed.paths=/js/lib/
spring.resources.chain.strategy.fixed.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 ResourceProperties
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.
Custom Favicon
As with other static resources, Spring Boot looks 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"
won’t 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 don’t 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
# We can change the parameter name, which is "format" by default:
# spring.mvc.contentnegotiation.parameter-name=myparam
# We can also register additional file extensions/media types with:
spring.mvc.contentnegotiation.media-types.markdown=text/markdown
If you understand the caveats and would still like your application to use suffix pattern matching, the following configuration is required:
spring.mvc.contentnegotiation.favor-path-extension=true
spring.mvc.pathmatch.use-suffix-pattern=true
Alternatively, rather than open all suffix patterns, it’s more secure to just support registered suffix patterns:
spring.mvc.contentnegotiation.favor-path-extension=true
spring.mvc.pathmatch.use-registered-suffix-pattern=true
# You can also register additional file extensions/media types with:
# spring.mvc.contentnegotiation.media-types.adoc=text/asciidoc
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, IntelliJ IDEA orders 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 templates on the classpath.
If you have this problem, you can reorder the classpath in the IDE to place the module’s classes and resources first.
Alternatively, you can configure the template prefix to search every templates directory on the classpath, as follows: classpath*:/templates/ .
|
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
).
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.
|
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 = AcmeController.class)
public class AcmeControllerAdvice extends ResponseEntityExceptionHandler {
@ExceptionHandler(YourException.class)
@ResponseBody
ResponseEntity<?> handleControllerException(HttpServletRequest request, Throwable ex) {
HttpStatus status = getStatus(request);
return new ResponseEntity<>(new CustomErrorType(status.value(), ex.getMessage()), status);
}
private HttpStatus getStatus(HttpServletRequest request) {
Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
if (statusCode == null) {
return HttpStatus.INTERNAL_SERVER_ERROR;
}
return HttpStatus.valueOf(statusCode);
}
}
In the preceding example, if YourException
is thrown by a controller defined in the same package as AcmeController
, a JSON representation of the CustomErrorType
POJO is used instead of the ErrorAttributes
representation.
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
folder.
Error pages can either be static HTML (that is, added under any of the static resource folders) 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 folder 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 folder 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
return ...
}
}
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
.
@Bean
public ErrorPageRegistrar errorPageRegistrar(){
return new MyErrorPageRegistrar();
}
// ...
private static class MyErrorPageRegistrar implements ErrorPageRegistrar {
@Override
public void registerErrorPages(ErrorPageRegistry registry) {
registry.addErrorPages(new 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:
|
@Bean
public FilterRegistrationBean myFilter() {
FilterRegistrationBean registration = new FilterRegistrationBean();
registration.setFilter(new MyFilter());
...
registration.setDispatcherTypes(EnumSet.allOf(DispatcherType.class));
return registration;
}
Note that the default FilterRegistrationBean
does not include the ERROR
dispatcher type.
CAUTION: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.
The request can only be forwarded 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
.
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.
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 MyConfiguration {
@Bean
public WebMvcConfigurer corsConfigurer() {
return new WebMvcConfigurer() {
@Override
public void addCorsMappings(CorsRegistry registry) {
registry.addMapping("/api/**");
}
};
}
}
4.7.2. 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 {
@GetMapping("/{user}")
public Mono<User> getUser(@PathVariable Long user) {
// ...
}
@GetMapping("/{user}/customers")
public Flux<Customer> getUserCustomers(@PathVariable Long user) {
// ...
}
@DeleteMapping("/{user}")
public Mono<User> deleteUser(@PathVariable Long user) {
// ...
}
}
“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 RoutingConfiguration {
@Bean
public RouterFunction<ServerResponse> monoRouterFunction(UserHandler userHandler) {
return route(GET("/{user}").and(accept(APPLICATION_JSON)), userHandler::getUser)
.andRoute(GET("/{user}/customers").and(accept(APPLICATION_JSON)), userHandler::getUserCustomers)
.andRoute(DELETE("/{user}").and(accept(APPLICATION_JSON)), userHandler::deleteUser);
}
}
@Component
public class UserHandler {
public Mono<ServerResponse> getUser(ServerRequest request) {
// ...
}
public Mono<ServerResponse> getUserCustomers(ServerRequest request) {
// ...
}
public Mono<ServerResponse> deleteUser(ServerRequest request) {
// ...
}
}
WebFlux 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
.
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:
import org.springframework.boot.web.codec.CodecCustomizer;
@Configuration(proxyBeanMethods = false)
public class MyConfiguration {
@Bean
public CodecCustomizer myCodecCustomizer() {
return codecConfigurer -> {
// ...
};
}
}
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/**
You can also customize the static resource locations by using spring.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.
Any resources with a path in /webjars/**
are served from jar files if they are packaged in the Webjars format.
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.
|
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).
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 a WebExceptionHandler
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:
public class CustomErrorWebExceptionHandler extends AbstractErrorWebExceptionHandler {
// Define constructor here
@Override
protected RouterFunction<ServerResponse> getRoutingFunction(ErrorAttributes errorAttributes) {
return RouterFunctions
.route(aPredicate, aHandler)
.andRoute(anotherPredicate, anotherHandler);
}
}
For a more complete picture, you can also subclass DefaultErrorWebExceptionHandler
directly and override specific methods.
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
folder.
Error pages can either be static HTML (that is, added under any of the static resource folders) or built with 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 folder 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 folder 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 |
---|---|
|
|
|
|
|
|
4.7.3. 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 JerseyConfig extends ResourceConfig {
public JerseyConfig() {
register(Endpoint.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 Endpoint {
@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
.
Both the servlet and the filter registrations can be given init parameters by using spring.jersey.init.*
to specify a map of properties.
4.7.4. Embedded Servlet Container Support
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 lifectyle.
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 Servlet 3.0+ javax.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.
|
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
file.
Common server settings include:
-
Network settings: Listen port for incoming HTTP requests (
server.port
), interface address to bind toserver.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.
|
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:
import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.boot.web.servlet.server.ConfigurableServletWebServerFactory;
import org.springframework.stereotype.Component;
@Component
public class CustomizationBean implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory> {
@Override
public void customize(ConfigurableServletWebServerFactory server) {
server.setPort(9000);
}
}
TomcatServletWebServerFactory , JettyServletWebServerFactory and UndertowServletWebServerFactory are dedicated variants of ConfigurableServletWebServerFactory that have additional customization setter methods for Tomcat, Jetty and Undertow respectively.
|
Customizing ConfigurableServletWebServerFactory Directly
If the preceding customization techniques are too limited, you can register the TomcatServletWebServerFactory
, JettyServletWebServerFactory
, or UndertowServletWebServerFactory
bean yourself.
@Bean
public ConfigurableServletWebServerFactory webServerFactory() {
TomcatServletWebServerFactory factory = new TomcatServletWebServerFactory();
factory.setPort(9000);
factory.setSessionTimeout(10, TimeUnit.MINUTES);
factory.addErrorPages(new ErrorPage(HttpStatus.NOT_FOUND, "/notfound.html"));
return factory;
}
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.
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.
4.7.5. 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.
4.7.6. 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.
4.8. RSocket
RSocket is a binary protocol for use on byte stream transports. It enables symmetric interaction models via 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.
4.8.1. 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.
Check out 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.
4.8.2. 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 (i.e. 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 # a mapping path is defined
spring.rsocket.server.transport=websocket # websocket is chosen as a transport
#spring.rsocket.server.port= # no port is defined
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 # the only required configuration
spring.rsocket.server.transport=tcp # you're free to configure other properties
4.8.3. 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.
4.8.4. 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.
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 shouldn’t create requesters with different setups using the same instance.
The following code shows a typical example:
@Service
public class MyService {
private final Mono<RSocketRequester> rsocketRequester;
public MyService(RSocketRequester.Builder rsocketRequesterBuilder) {
this.rsocketRequester = rsocketRequesterBuilder
.connectTcp("example.org", 9898).cache();
}
public Mono<User> someRSocketCall(String name) {
return this.rsocketRequester.flatMap(req ->
req.route("user").data(name).retrieveMono(User.class));
}
}
4.9. 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 INFO level when the application starts, as shown in the following example:
Using generated security password: 78fa095d-3f4c-48b1-ad50-e24c31d5cf35
If you fine-tune your logging configuration, ensure that the org.springframework.boot.autoconfigure.security category is set to log INFO -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.
4.9.1. 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 OAuth 2 Client and Resource Server, add a bean of type WebSecurityConfigurerAdapter
(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
.
Access rules can be overridden by adding a custom WebSecurityConfigurerAdapter
.
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.
4.9.2. 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
.
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:
@Bean
public SecurityWebFilterChain springSecurityFilterChain(ServerHttpSecurity http) {
return http
.authorizeExchange()
.matchers(PathRequest.toStaticResources().atCommonLocations()).permitAll()
.pathMatchers("/foo", "/bar")
.authenticated().and()
.formLogin().and()
.build();
}
4.9.3. 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 make it easy to set up an 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-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=https://my-redirect-uri.com
spring.security.oauth2.client.registration.my-client-1.client-authentication-method=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=https://my-redirect-uri.com
spring.security.oauth2.client.registration.my-client-2.client-authentication-method=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/oauth/authorize
spring.security.oauth2.client.provider.my-oauth-provider.token-uri=https://my-auth-server/oauth/token
spring.security.oauth2.client.provider.my-oauth-provider.user-info-uri=https://my-auth-server/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/token_keys
spring.security.oauth2.client.provider.my-oauth-provider.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 the 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/
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 WebSecurityConfigurerAdapter
that resembles the following:
public class OAuth2LoginSecurityConfig extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
http
.authorizeRequests()
.anyRequest().authenticated()
.and()
.oauth2Login()
.redirectionEndpoint()
.baseUri("/custom-callback");
}
}
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
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.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.
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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 via 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
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
Currently, Spring Security does not provide support for implementing an OAuth 2.0 Authorization Server.
However, this functionality is available from the Spring Security OAuth project, which will eventually be superseded by Spring Security completely.
Until then, you can use the spring-security-oauth2-autoconfigure
module to easily set up an OAuth 2.0 authorization server; see its documentation for instructions.
4.9.4. 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 make it easy 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.identityprovider.verification.credentials[0].certificate-location=path-to-verification-cert
spring.security.saml2.relyingparty.registration.my-relying-party1.identityprovider.entity-id=remote-idp-entity-id1
spring.security.saml2.relyingparty.registration.my-relying-party1.identityprovider.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.identityprovider.verification.credentials[0].certificate-location=path-to-other-verification-cert
spring.security.saml2.relyingparty.registration.my-relying-party2.identityprovider.entity-id=remote-idp-entity-id2
spring.security.saml2.relyingparty.registration.my-relying-party2.identityprovider.sso-url=https://remoteidp2.sso.url
4.9.5. Actuator Security
For security purposes, all actuators other than /health
and /info
are disabled by default.
The management.endpoints.web.exposure.include
property can be used to enable the actuators.
If Spring Security is on the classpath and no other WebSecurityConfigurerAdapter is present, all actuators other than /health
and /info
are secured by Spring Boot auto-configuration.
If you define a custom WebSecurityConfigurerAdapter
, Spring Boot auto-configuration will back off and you will be in full control of actuator access rules.
Before setting the management.endpoints.web.exposure.include , ensure that the exposed actuators do not contain sensitive information and/or are secured by placing them behind a firewall or by something like Spring Security.
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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), PUT
or DELETE
will 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. |
Additional information about CSRF protection can be found in the Spring Security Reference Guide.
4.10. Working with SQL Databases
The Spring Framework provides extensive support for working with SQL databases, from direct JDBC access using 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.
4.10.1. 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 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 .
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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.
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Connection to a Production Database
Production database connections can also be auto-configured by using a pooling DataSource
.
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. -
If neither HikariCP nor the Tomcat pooling datasource are available and if Commons DBCP2 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.
If you define your own DataSource bean, auto-configuration does not occur.
|
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.driver-class-name=com.mysql.jdbc.Driver
You should at least specify the URL by setting the spring.datasource.url property.
Otherwise, Spring Boot tries to auto-configure an embedded database.
|
You often do not need to specify the driver-class-name , since Spring Boot can deduce it for most databases from the url .
|
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.*
, and spring.datasource.dbcp2.*
).
Refer to 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:
# Number of ms to wait before throwing an exception if no connection is available.
spring.datasource.tomcat.max-wait=10000
# Maximum number of active connections that can be allocated from this pool at the same time.
spring.datasource.tomcat.max-active=50
# Validate the connection before borrowing it from the pool.
spring.datasource.tomcat.test-on-borrow=true
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
4.10.2. 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:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Component;
@Component
public class MyBean {
private final JdbcTemplate jdbcTemplate;
@Autowired
public MyBean(JdbcTemplate jdbcTemplate) {
this.jdbcTemplate = jdbcTemplate;
}
// ...
}
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
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.
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4.10.3. 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: Makes it easy to implement JPA-based repositories.
-
Spring ORMs: 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, all packages below your main configuration class (the one annotated with @EnableAutoConfiguration
or @SpringBootApplication
) are searched.
Any classes annotated with @Entity
, @Embeddable
, or @MappedSuperclass
are considered.
A typical entity class resembles the following example:
package com.example.myapp.domain;
import java.io.Serializable;
import javax.persistence.*;
@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 shouldn't 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
}
You can customize entity scanning locations by using the @EntityScan annotation.
See the “Separate @Entity Definitions from Spring Configuration” how-to.
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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, repositories are searched from the package containing your main configuration class (the one annotated with @EnableAutoConfiguration
or @SpringBootApplication
) down.
The following example shows a typical Spring Data repository interface definition:
package com.example.myapp.domain;
import org.springframework.data.domain.*;
import org.springframework.data.repository.*;
public interface CityRepository extends Repository<City, Long> {
Page<City> findAll(Pageable pageable);
City findByNameAndStateAllIgnoringCase(String name, String state);
}
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.
We have barely scratched the surface of Spring Data JPA. For complete details, see the Spring Data JPA 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
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:
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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
.
4.10.4. 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 a JdbcConfiguration
subclass to your application.
For complete details of Spring Data JDBC, please refer to the reference documentation. |
4.10.5. 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 .
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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.
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4.10.6. 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 @Autowire
it, as shown in the following example:
@Component
public class JooqExample implements CommandLineRunner {
private final DSLContext create;
@Autowired
public JooqExample(DSLContext dslContext) {
this.create = dslContext;
}
}
The jOOQ manual tends to use a variable named create to hold the DSLContext .
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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);
}
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 @Bean
definitions, which is used when the jOOQ Configuration
is created.
You can define beans for the following jOOQ Types:
-
ConnectionProvider
-
ExecutorProvider
-
TransactionProvider
-
RecordMapperProvider
-
RecordUnmapperProvider
-
Settings
-
RecordListenerProvider
-
ExecuteListenerProvider
-
VisitListenerProvider
-
TransactionListenerProvider
You can also create your own org.jooq.Configuration
@Bean
if you want to take complete control of the jOOQ configuration.
4.11. Working with NoSQL Technologies
Spring Data provides additional projects that help you access a variety of NoSQL technologies, including:
Spring Boot provides auto-configuration for Redis, MongoDB, Neo4j, Elasticsearch, Solr Cassandra, Couchbase, and LDAP. You can make use of the other projects, but you must configure them yourself. Refer to the appropriate reference documentation at spring.io/projects/spring-data.
4.11.1. 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.
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Connecting to Redis
You can inject an auto-configured RedisConnectionFactory
, StringRedisTemplate
, or vanilla RedisTemplate
instance as you would any other Spring Bean.
By default, the instance tries to connect to a Redis server at localhost:6379
.
The following listing shows an example of such a bean:
@Component
public class MyBean {
private StringRedisTemplate template;
@Autowired
public MyBean(StringRedisTemplate template) {
this.template = template;
}
// ...
}
You can also register an arbitrary number of beans that implement LettuceClientConfigurationBuilderCustomizer for more advanced customizations.
If you use Jedis, JedisClientConfigurationBuilderCustomizer is also available.
|
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, if commons-pool2
is on the classpath, you get a pooled connection factory.
4.11.2. 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 Mongo 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:
import org.springframework.data.mongodb.MongoDatabaseFactory;
import com.mongodb.client.MongoDatabase;
@Component
public class MyBean {
private final MongoDatabaseFactory mongo;
@Autowired
public MyBean(MongoDbFactory mongo) {
this.mongo = mongo;
}
// ...
public void example() {
MongoDatabase db = mongo.getMongoDatabase();
// ...
}
}
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]:12345,mongo2.example.com:23456/test
Alternatively, you can specify a host
/port
.
For example, you might declare the following settings in your application.properties
:
spring.data.mongodb.host=mongoserver
spring.data.mongodb.port=27017
If you have defined your own MongoClient
, it will be used to auto-configure a suitable MongoDatabaseFactory
.
If you use the Mongo 3.0 Java driver, spring.data.mongodb.host and spring.data.mongodb.port are not supported.
In such cases, spring.data.mongodb.uri should be used to provide all of the configuration.
|
If spring.data.mongodb.port is not specified, the default of 27017 is used.
You could delete this line from the example shown earlier.
|
If you do not use Spring Data Mongo, 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 hasn’t 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:
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.stereotype.Component;
@Component
public class MyBean {
private final MongoTemplate mongoTemplate;
public MyBean(MongoTemplate mongoTemplate) {
this.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 Mongo data class rather than a JPA @Entity
, it works in the same way, as shown in the following example:
package com.example.myapp.domain;
import org.springframework.data.domain.*;
import org.springframework.data.repository.*;
public interface CityRepository extends Repository<City, Long> {
Page<City> findAll(Pageable pageable);
City findByNameAndStateAllIgnoringCase(String name, String state);
}
You can customize document scanning locations by using the @EntityScan annotation.
|
For complete details of Spring Data MongoDB, including its rich object mapping technologies, refer to its reference documentation. |
Embedded Mongo
Spring Boot offers auto-configuration for Embedded Mongo.
To use it in your Spring Boot application, add a dependency on de.flapdoodle.embed:de.flapdoodle.embed.mongo
.
The port that Mongo listens on can be configured by setting the spring.data.mongodb.port
property.
To use a randomly allocated free port, use a value of 0.
The MongoClient
created by MongoAutoConfiguration
is automatically configured to use the randomly allocated port.
If you do not configure a custom port, the embedded support uses a random port (rather than 27017) by default. |
If you have SLF4J on the classpath, the output produced by Mongo is automatically routed to a logger named org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongo
.
You can declare your own IMongodConfig
and IRuntimeConfig
beans to take control of the Mongo instance’s configuration and logging routing.
The download configuration can be customized by declaring a DownloadConfigBuilderCustomizer
bean.
4.11.3. 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.ogm.session.Session
.
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 Session
:
@Component
public class MyBean {
private final Session session;
@Autowired
public MyBean(Session session) {
this.session = session;
}
// ...
}
You can configure the uri and credentials to use by setting the spring.data.neo4j.*
properties, as shown in the following example:
spring.data.neo4j.uri=bolt://my-server:7687
spring.data.neo4j.username=neo4j
spring.data.neo4j.password=secret
You can take full control over the session creation by adding either an org.neo4j.ogm.config.Configuration
bean or an org.neo4j.ogm.session.SessionFactory
bean.
Using the Embedded Mode
If you add org.neo4j:neo4j-ogm-embedded-driver
to the dependencies of your application, Spring Boot automatically configures an in-process embedded instance of Neo4j that does not persist any data when your application shuts down.
As the embedded Neo4j OGM driver does not provide the Neo4j kernel itself, you have to declare org.neo4j:neo4j as dependency yourself.
Refer to the Neo4j OGM documentation for a list of compatible versions.
|
The embedded driver takes precedence over the other drivers when there are multiple drivers on the classpath.
You can explicitly disable the embedded mode by setting spring.data.neo4j.embedded.enabled=false
.
Data Neo4j Tests automatically make use of an embedded Neo4j instance if the embedded driver and Neo4j kernel are on the classpath as described above.
You can enable persistence for the embedded mode by providing a path to a database file in your configuration, e.g. spring.data.neo4j.uri=file://var/tmp/graph.db .
|
Using Native Types
Neo4j-OGM can map some types, like those in java.time.*
, to String
-based properties or to one of the native types that Neo4j provides.
For backwards compatibility reasons the default for Neo4j-OGM is to use a String
-based representation.
To use native types, add a dependency on either org.neo4j:neo4j-ogm-bolt-native-types
or org.neo4j:neo4j-ogm-embedded-native-types
, and configure the spring.data.neo4j.use-native-types
property as shown in the following example:
spring.data.neo4j.use-native-types=true
Neo4jSession
By default, if you are running a web application, the session is bound to the thread for the entire processing of the request (that is, it uses the "Open Session in View" pattern).
If you do not want this behavior, add the following line to your application.properties
file:
spring.data.neo4j.open-in-view=false
Spring Data Neo4j Repositories
Spring Data includes repository support for Neo4j.
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 Neo4j OGM @NodeEntity
rather than JPA @Entity
and the repository abstraction works in the same way, as shown in the following example:
package com.example.myapp.domain;
import java.util.Optional;
import org.springframework.data.neo4j.repository.*;
public interface CityRepository extends Neo4jRepository<City, Long> {
Optional<City> findOneByNameAndState(String name, String state);
}
The spring-boot-starter-data-neo4j
“Starter” enables the repository support as well as transaction management.
You can customize the locations to look for repositories and entities by using @EnableNeo4jRepositories
and @EntityScan
respectively on a @Configuration
-bean.
For complete details of Spring Data Neo4j, including its object mapping technologies, refer to the reference documentation. |
4.11.4. Solr
Apache Solr is a search engine.
Spring Boot offers basic auto-configuration for the Solr 5 client library and the abstractions on top of it provided by Spring Data Solr.
There is a spring-boot-starter-data-solr
“Starter” for collecting the dependencies in a convenient way.
Connecting to Solr
You can inject an auto-configured SolrClient
instance as you would any other Spring bean.
By default, the instance tries to connect to a server at localhost:8983/solr
.
The following example shows how to inject a Solr bean:
@Component
public class MyBean {
private SolrClient solr;
@Autowired
public MyBean(SolrClient solr) {
this.solr = solr;
}
// ...
}
If you add your own @Bean
of type SolrClient
, it replaces the default.
Spring Data Solr Repositories
Spring Data includes repository support for Apache Solr. As with the JPA repositories discussed earlier, the basic principle is that queries are automatically constructed for you based on method names.
In fact, both Spring Data JPA and Spring Data Solr share the same common infrastructure.
You could take the JPA example from earlier and, assuming that City
is now a @SolrDocument
class rather than a JPA @Entity
, it works in the same way.
IP: For complete details of Spring Data Solr, refer to the reference documentation.
4.11.5. Elasticsearch
Elasticsearch is an open source, distributed, RESTful search and analytics engine. Spring Boot offers basic auto-configuration for Elasticsearch.
Spring Boot supports several clients:
-
The official Java "Low Level" and "High Level" REST clients
-
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 and the "High Level" client.
If you have the org.elasticsearch.client:elasticsearch-rest-client
dependency on the classpath, Spring Boot will auto-configure and register a RestClient
bean that by default targets localhost:9200
.
You can further tune how RestClient
is configured, as shown in the following example:
spring.elasticsearch.rest.uris=https://search.example.com:9200
spring.elasticsearch.rest.read-timeout=10s
spring.elasticsearch.rest.username=user
spring.elasticsearch.rest.password=secret
You can also register an arbitrary number of beans that implement RestClientBuilderCustomizer
for more advanced customizations.
To take full control over the registration, define a RestClient
bean.
If you have the org.elasticsearch.client:elasticsearch-rest-high-level-client
dependency on the classpath, Spring Boot will auto-configure a RestHighLevelClient
, which wraps any existing RestClient
bean, reusing its HTTP configuration.
Connecting to Elasticsearch using Reactive REST clients
Spring Data Elasticsearch ships ReactiveElasticsearchClient
for querying Elasticsearch instances in a reactive fashion.
It is built on top of WebFlux’s WebClient
, so both spring-boot-starter-elasticsearch
and spring-boot-starter-webflux
dependencies are useful to enable this support.
By default, Spring Boot will auto-configure and register a ReactiveElasticsearchClient
bean that targets localhost:9200
.
You can further tune how it is configured, as shown in the following example:
spring.data.elasticsearch.client.reactive.endpoints=search.example.com:9200
spring.data.elasticsearch.client.reactive.use-ssl=true
spring.data.elasticsearch.client.reactive.socket-timeout=10s
spring.data.elasticsearch.client.reactive.username=user
spring.data.elasticsearch.client.reactive.password=secret
If the configuration properties are not enough and you’d like to fully control the client
configuration, you can register a custom ClientConfiguration
bean.
Connecting to Elasticsearch by Using Spring Data
To connect to Elasticsearch, a RestHighLevelClient
bean must be defined,
auto-configured by Spring Boot or manually provided by the application (see previous sections).
With this configuration in place, an
ElasticsearchRestTemplate
can be injected like any other Spring bean,
as shown in the following example:
@Component
public class MyBean {
private final ElasticsearchRestTemplate template;
public MyBean(ElasticsearchRestTemplate template) {
this.template = template;
}
// ...
}
In the presence of spring-data-elasticsearch
and the required dependencies for using a WebClient
(typically spring-boot-starter-webflux
), 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.
For complete details of Spring Data Elasticsearch, refer to 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
4.11.6. 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.data.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.data.cassandra.keyspace-name=mykeyspace
spring.data.cassandra.contact-points=cassandrahost1:9042,cassandrahost2:9042
spring.data.cassandra.local-datacenter=datacenter1
You can also register an arbitrary number of beans that implement DriverConfigLoaderBuilderCustomizer
for more advanced driver customizations.
The CqlSession
can be customized with a bean of type CqlSessionBuilderCustomizer
.
If you’re using 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;
}
// ...
}
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 to annotate finder methods with @Query
.
For complete details of Spring Data Cassandra, refer to the reference documentation. |
4.11.7. 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 Bucket
and Cluster
by adding the Couchbase SDK and some configuration.
The spring.couchbase.*
properties can be used to customize the connection.
Generally, you provide the bootstrap hosts, bucket name, and password, as shown in the following example:
spring.couchbase.bootstrap-hosts=my-host-1,192.168.1.123
spring.couchbase.bucket.name=my-bucket
spring.couchbase.bucket.password=secret
You need to provide at least the bootstrap host(s), in which case the bucket name is default and the password is an empty String.
Alternatively, you can define your own org.springframework.data.couchbase.config.CouchbaseConfigurer @Bean to take control over the whole configuration.
|
It is also possible to customize some of the CouchbaseEnvironment
settings.
For instance, the following configuration changes the timeout to use to open a new Bucket
and enables SSL support:
spring.couchbase.env.timeouts.connect=3000
spring.couchbase.env.ssl.key-store=/location/of/keystore.jks
spring.couchbase.env.ssl.key-store-password=secret
Check the spring.couchbase.env.*
properties for more details.
Spring Data Couchbase Repositories
Spring Data includes repository support for Couchbase. For complete details of Spring Data Couchbase, refer to the reference documentation.
You can inject an auto-configured CouchbaseTemplate
instance as you would with any other Spring Bean, provided a default CouchbaseConfigurer
is available (which happens when you enable Couchbase support, as explained earlier).
The following examples shows how to inject a Couchbase bean:
@Component
public class MyBean {
private final CouchbaseTemplate template;
@Autowired
public MyBean(CouchbaseTemplate template) {
this.template = template;
}
// ...
}
There are a few beans that you can define in your own configuration to override those provided by the auto-configuration:
-
A
CouchbaseTemplate
@Bean
with a name ofcouchbaseTemplate
. -
An
IndexManager
@Bean
with a name ofcouchbaseIndexManager
. -
A
CustomConversions
@Bean
with a name ofcouchbaseCustomConversions
.
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 SomeConfiguration {
@Bean(BeanNames.COUCHBASE_CUSTOM_CONVERSIONS)
public CustomConversions myCustomConversions() {
return new CustomConversions(...);
}
// ...
}
If you want to fully bypass the auto-configuration for Spring Data Couchbase, provide your own implementation of org.springframework.data.couchbase.config.AbstractCouchbaseDataConfiguration .
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4.11.8. 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
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. For complete details of Spring Data LDAP, refer to 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;
@Autowired
public MyBean(LdapTemplate template) {
this.template = template;
}
// ...
}
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
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:
|
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.
4.11.9. InfluxDB
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, as shown in the following example:
spring.influx.url=https://172.0.0.1:8086
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.
4.12. 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 via the @EnableCaching
annotation.
Check the relevant section of the Spring Framework reference for more details. |
In a nutshell, adding caching to an operation of your service is as easy as adding the relevant annotation to its method, as shown in the following example:
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Component;
@Component
public class MathService {
@Cacheable("piDecimals")
public int computePiDecimal(int i) {
// ...
}
}
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.
4.12.1. 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)
It is also possible to force a particular cache provider by setting the spring.cache.type property.
Use this property if you need to disable caching altogether in certain environment (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, EhCache 2.x, 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 be passed down to the underlying map:
@Bean
public CacheManagerCustomizer<ConcurrentMapCacheManager> cacheManagerCustomizer() {
return new CacheManagerCustomizer<ConcurrentMapCacheManager>() {
@Override
public void customize(ConcurrentMapCacheManager cacheManager) {
cacheManager.setAllowNullValues(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.acme.MyCachingProvider
spring.cache.jcache.config=classpath:acme.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.
|
EhCache 2.x
EhCache 2.x is used if a file named ehcache.xml
can be found at the root of the classpath.
If EhCache 2.x is found, the EhCacheCacheManager
provided by the spring-boot-starter-cache
“Starter” is used to bootstrap the cache manager.
An alternate configuration file can be provided as well, as shown in the following example:
spring.cache.ehcache.config=classpath:config/another-config.xml
Hazelcast
Spring Boot has general support for Hazelcast.
If a HazelcastInstance
has been auto-configured, it is automatically wrapped in a CacheManager
.
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
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.
The support of Infinispan in Spring Boot is restricted to the embedded mode and is quite basic. If you want more options, you should use the official Infinispan Spring Boot starter instead. See Infinispan’s documentation for more details. |
Couchbase
If the Couchbase Java client and the couchbase-spring-cache
implementation are available and Couchbase is configured, a CouchbaseCacheManager
is auto-configured.
It is also possible to create additional caches on startup by setting the spring.cache.cache-names
property.
These caches operate on the Bucket
that was auto-configured.
You can also create additional caches on another Bucket
by using the customizer.
Assume you need two caches (cache1
and cache2
) on the "main" Bucket
and one (cache3
) cache with a custom time to live of 2 seconds on the “another” Bucket
.
You can create the first two caches through configuration, as follows:
spring.cache.cache-names=cache1,cache2
Then you can define a @Configuration
class to configure the extra Bucket
and the cache3
cache, as follows:
@Configuration(proxyBeanMethods = false)
public class CouchbaseCacheConfiguration {
private final Cluster cluster;
public CouchbaseCacheConfiguration(Cluster cluster) {
this.cluster = cluster;
}
@Bean
public Bucket anotherBucket() {
return this.cluster.openBucket("another", "secret");
}
@Bean
public CacheManagerCustomizer<CouchbaseCacheManager> cacheManagerCustomizer() {
return c -> {
c.prepareCache("cache3", CacheBuilder.newInstance(anotherBucket())
.withExpiration(2));
};
}
}
This sample configuration reuses the Cluster
that was created through auto-configuration.
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=600000
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’re looking for customizing 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
:
@Bean
public RedisCacheManagerBuilderCustomizer myRedisCacheManagerBuilderCustomizer() {
return (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
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.
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
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.
4.13. 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.
4.13.1. JMS
The javax.jms.ConnectionFactory
interface provides a standard method of creating a javax.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.
ActiveMQ Support
When ActiveMQ is available on the classpath, Spring Boot can also configure a ConnectionFactory
.
If the broker is present, an embedded broker is automatically started and configured (provided no broker URL is specified through configuration).
If you use spring-boot-starter-activemq , the necessary dependencies to connect or embed an ActiveMQ instance are provided, as is the Spring infrastructure to integrate with JMS.
|
ActiveMQ configuration is controlled by external configuration properties in spring.activemq.*
.
For example, you might declare the following section in application.properties
:
spring.activemq.broker-url=tcp://192.168.1.210:9876
spring.activemq.user=admin
spring.activemq.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
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
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 creates a destination if it does not yet exist so that destinations are resolved against their provided names.
Artemis Support
Spring Boot can auto-configure a ConnectionFactory
when it detects that 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 Artemis instance are provided, as well as the Spring infrastructure to integrate with JMS.
Adding org.apache.activemq:artemis-jms-server to your application lets you use embedded mode.
|
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.host=192.168.1.210
spring.artemis.port=9876
spring.artemis.user=admin
spring.artemis.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
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.artemis.pool.enabled=true
spring.artemis.pool.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 Artemis configuration or the names provided through configuration.
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
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:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jms.core.JmsTemplate;
import org.springframework.stereotype.Component;
@Component
public class MyBean {
private final JmsTemplate jmsTemplate;
@Autowired
public MyBean(JmsTemplate jmsTemplate) {
this.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 .
|
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
or a MessageConverter
beans is defined, it is associated automatically to 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) {
// ...
}
}
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)
static class JmsConfiguration {
@Bean
public DefaultJmsListenerContainerFactory myFactory(
DefaultJmsListenerContainerFactoryConfigurer configurer) {
DefaultJmsListenerContainerFactory factory =
new DefaultJmsListenerContainerFactory();
configurer.configure(factory, connectionFactory());
factory.setMessageConverter(myMessageConverter());
return factory;
}
}
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) {
// ...
}
}
4.13.2. 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”.
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
Alternatively, you could configure the same connection using the addresses
attribute:
spring.rabbitmq.addresses=amqp://admin:secret@localhost
If a ConnectionNameStrategy
bean exists in the context, it will be automatically used to name connections created by the auto-configured ConnectionFactory
.
See RabbitProperties
for more of the supported options.
See Understanding AMQP, the protocol used by RabbitMQ for more details. |
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:
import org.springframework.amqp.core.AmqpAdmin;
import org.springframework.amqp.core.AmqpTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class MyBean {
private final AmqpAdmin amqpAdmin;
private final AmqpTemplate amqpTemplate;
@Autowired
public MyBean(AmqpAdmin amqpAdmin, AmqpTemplate amqpTemplate) {
this.amqpAdmin = amqpAdmin;
this.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
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.
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) {
// ...
}
}
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)
static class RabbitConfiguration {
@Bean
public SimpleRabbitListenerContainerFactory myFactory(
SimpleRabbitListenerContainerFactoryConfigurer configurer) {
SimpleRabbitListenerContainerFactory factory =
new SimpleRabbitListenerContainerFactory();
configurer.configure(factory, connectionFactory);
factory.setMessageConverter(myMessageConverter());
return factory;
}
}
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) {
// ...
}
}
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.
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4.13.3. 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
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.
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 kafkaTemplate;
@Autowired
public MyBean(KafkaTemplate kafkaTemplate) {
this.kafkaTemplate = kafkaTemplate;
}
// ...
}
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 .
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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) {
// ...
}
}
If a KafkaTransactionManager
bean is defined, it is automatically associated to the container factory.
Similarly, if a ErrorHandler
, 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.
|
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 via 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 just 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, simply wire StreamsBuilder
into your @Bean
as shown in the following example:
@Configuration(proxyBeanMethods = false)
@EnableKafkaStreams
public static class KafkaStreamsExampleConfiguration {
@Bean
public KStream<Integer, String> kStream(StreamsBuilder streamsBuilder) {
KStream<Integer, String> stream = streamsBuilder.stream("ks1In");
stream.map((k, v) -> new KeyValue<>(k, v.toUpperCase())).to("ks1Out",
Produced.with(Serdes.Integer(), new JsonSerde<>()));
return stream;
}
}
By default, the streams managed by the StreamBuilder
object it creates are started automatically.
You can customize this behaviour using the spring.kafka.streams.auto-startup
property.
Additional Kafka Properties
The properties supported by auto configuration are shown in Common Application properties. Note that, for the most part, these properties (hyphenated or camelCase) map directly to the Apache Kafka dotted properties. Refer to the Apache Kafka documentation for details.
The first few of these properties apply to all components (producers, consumers, admins, and streams) but can be specified at the component level if you wish to use different values. 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 producer or consumer 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
This sets the common prop.one
Kafka property to first
(applies to producers, consumers and admins), 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,org.acme
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
Properties set in this way override any configuration item that Spring Boot explicitly supports. |
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");
}
-
Configure a property name on the
@EmbeddedKafka
annotation:
@EmbeddedKafka(topics = "someTopic",
bootstrapServersProperty = "spring.kafka.bootstrap-servers")
-
Use a placeholder in configuration properties:
spring.kafka.bootstrap-servers=${spring.embedded.kafka.brokers}
4.14. Calling REST Services with RestTemplate
If you need to call remote REST services from your application, you can use the Spring Framework’s RestTemplate
class.
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
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);
}
}
RestTemplateBuilder includes a number of useful methods that can be used to quickly configure a RestTemplate .
For example, to add BASIC auth support, you can use builder.basicAuthentication("user", "password").build() .
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4.14.1. 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
:
static class ProxyCustomizer implements RestTemplateCustomizer {
@Override
public void customize(RestTemplate restTemplate) {
HttpHost proxy = new HttpHost("proxy.example.com");
HttpClient httpClient = HttpClientBuilder.create().setRoutePlanner(new DefaultProxyRoutePlanner(proxy) {
@Override
public HttpHost determineProxy(HttpHost target, HttpRequest request, HttpContext context)
throws HttpException {
if (target.getHostName().equals("192.168.0.5")) {
return null;
}
return super.determineProxy(target, request, context);
}
}).build();
restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory(httpClient));
}
}
Finally, the most extreme (and rarely used) option is to create your own RestTemplateBuilder
bean.
Doing so switches off the auto-configuration of a RestTemplateBuilder
and prevents any RestTemplateCustomizer
beans from being used.
4.15. Calling REST Services with WebClient
If you have Spring WebFlux on your classpath, you can also choose to use WebClient
to call remote REST services.
Compared to RestTemplate
, this client has a more functional feel and is fully reactive.
You can learn more about the WebClient
in the dedicated section in the Spring Framework docs.
Spring Boot creates and pre-configures a WebClient.Builder
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, 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);
}
}
4.15.1. WebClient Runtime
Spring Boot will auto-detect which ClientHttpConnector
to use to drive WebClient
, depending on the libraries available on the application classpath.
For now, Reactor Netty and Jetty RS client are supported.
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 it 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.
4.15.2. 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.
4.16. 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 javax.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) {
...
}
}
4.17. Sending Email
The Spring Framework provides an easy 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
It is also possible to configure a JavaMailSender
with an existing Session
from JNDI:
spring.mail.jndi-name=mail/Session
When a jndi-name
is set, it takes precedence over all other Session-related settings.
4.18. Distributed Transactions with JTA
Spring Boot supports distributed JTA transactions across multiple XA resources by using either an Atomikos or Bitronix embedded transaction manager. JTA transactions are also supported when deploying to a suitable Java EE Application Server.
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.
4.18.1. Using an Atomikos Transaction Manager
Atomikos is a popular open source transaction manager which can be embedded into your Spring Boot application.
You can use the spring-boot-starter-jta-atomikos
starter to pull in the appropriate Atomikos libraries.
Spring Boot auto-configures Atomikos and ensures that appropriate depends-on
settings are applied to your Spring beans for correct startup and shutdown ordering.
By default, Atomikos transaction logs are written to a transaction-logs
directory in your application’s home directory (the directory in which your application jar file resides).
You can customize the location of this directory by setting a spring.jta.log-dir
property in your application.properties
file.
Properties starting with spring.jta.atomikos.properties
can also be used to customize the Atomikos UserTransactionServiceImp
.
See the AtomikosProperties
Javadoc for complete details.
To ensure that multiple transaction managers can safely coordinate the same resource managers, each Atomikos instance must be configured with a unique ID.
By default, this ID is the IP address of the machine on which Atomikos is running.
To ensure uniqueness in production, you should configure the spring.jta.transaction-manager-id property with a different value for each instance of your application.
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4.18.2. Using a Bitronix Transaction Manager
Bitronix is a popular open-source JTA transaction manager implementation.
You can use the spring-boot-starter-jta-bitronix
starter to add the appropriate Bitronix dependencies to your project.
As with Atomikos, Spring Boot automatically configures Bitronix and post-processes your beans to ensure that startup and shutdown ordering is correct.
By default, Bitronix transaction log files (part1.btm
and part2.btm
) are written to a transaction-logs
directory in your application home directory.
You can customize the location of this directory by setting the spring.jta.log-dir
property.
Properties starting with spring.jta.bitronix.properties
are also bound to the bitronix.tm.Configuration
bean, allowing for complete customization.
See the Bitronix documentation for details.
To ensure that multiple transaction managers can safely coordinate the same resource managers, each Bitronix instance must be configured with a unique ID.
By default, this ID is the IP address of the machine on which Bitronix is running.
To ensure uniqueness in production, you should configure the spring.jta.transaction-manager-id property with a different value for each instance of your application.
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4.18.3. Using a Java EE Managed Transaction Manager
If you package your Spring Boot application as a war
or ear
file and deploy it to a Java 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).
If you use 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
.
4.18.4. Mixing XA and Non-XA JMS Connections
When using JTA, the primary JMS ConnectionFactory
bean is XA-aware and participates in distributed transactions.
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 inject the nonXaJmsConnectionFactory
bean rather than the @Primary
jmsConnectionFactory
bean.
For consistency, the jmsConnectionFactory
bean is also provided by using the bean alias xaJmsConnectionFactory
.
The following example shows how to inject ConnectionFactory
instances:
// Inject the primary (XA aware) ConnectionFactory
@Autowired
private ConnectionFactory defaultConnectionFactory;
// Inject the XA aware ConnectionFactory (uses the alias and injects the same as above)
@Autowired
@Qualifier("xaJmsConnectionFactory")
private ConnectionFactory xaConnectionFactory;
// Inject the non-XA aware ConnectionFactory
@Autowired
@Qualifier("nonXaJmsConnectionFactory")
private ConnectionFactory nonXaConnectionFactory;
4.18.5. Supporting an Alternative Embedded Transaction Manager
The XAConnectionFactoryWrapper
and XADataSourceWrapper
interfaces can be used to support alternative 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
.
The BitronixXAConnectionFactoryWrapper and BitronixXADataSourceWrapper provide good examples of how to write XA wrappers.
4.19. 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.
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
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.
If hazelcast-client
is present on the classpath, 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
in the working directory or at the root of the classpath.
Spring Boot also has explicit caching support for Hazelcast.
If caching is enabled, the HazelcastInstance is automatically wrapped in a CacheManager implementation.
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4.20. 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
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
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.
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 via 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 SampleJob extends QuartzJobBean {
private MyService myService;
private String name;
// Inject "MyService" bean
public void setMyService(MyService myService) { ... }
// Inject the "name" job data property
public void setName(String name) { ... }
@Override
protected void executeInternal(JobExecutionContext context)
throws JobExecutionException {
...
}
}
4.21. Task Execution and Scheduling
In the absence of an Executor
bean in the context, Spring Boot auto-configures a ThreadPoolTaskExecutor
with sensible defaults that can be automatically associated to asynchronous task execution (@EnableAsync
) and Spring MVC asynchronous request processing.
If you have defined a custom The 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
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 ThreadPoolTaskScheduler
can also be auto-configured if need to be associated to scheduled task execution (@EnableScheduling
).
The thread pool uses one thread by default and those settings can be fine-tuned using the spring.task.scheduling
namespace.
Both a TaskExecutorBuilder
bean and a TaskSchedulerBuilder
bean are made available in the context if a custom executor or scheduler needs to be created.
4.22. 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 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
See the IntegrationAutoConfiguration
and IntegrationProperties
classes for more details.
By default, if a Micrometer meterRegistry
bean is present, Spring Integration metrics will be managed by Micrometer.
If you wish to use legacy Spring Integration metrics, add a DefaultMetricsFactory
bean to the application context.
4.23. 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:
-
JDBC
-
Redis
-
Hazelcast
-
MongoDB
When building a reactive web application, the following stores can be auto-configured:
-
Redis
-
MongoDB
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, you must choose the StoreType
that you wish to use to store the sessions.
For instance, to use JDBC as the back-end store, you can configure your application as follows:
spring.session.store-type=jdbc
You can disable Spring Session by setting the store-type to none .
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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
For setting the timeout of the session you can use the spring.session.timeout
property.
If that property is not set, the auto-configuration falls back to the value of server.servlet.session.timeout
.
4.24. Monitoring and Management over JMX
Java Management Extensions (JMX) provide a standard mechanism to monitor and manage applications.
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 will use that and default to the VM MBeanServer
if necessary.
If all that fails, a new MBeanServer
will be created.
See the JmxAutoConfiguration
class for more details.
4.25. 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.
The starter also brings the vintage engine so that you can run both JUnit 4 and JUnit 5 tests. If you have migrated your tests to JUnit 5, you should exclude JUnit 4 support, as shown in the following example:
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4.25.1. Test Scope Dependencies
The spring-boot-starter-test
“Starter” (in the test
scope
) contains the following provided libraries:
-
JUnit 5 (including the vintage engine for backward compatibility with JUnit 4): 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.
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.
4.25.2. 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.
4.25.3. 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, don’t forget to also add @RunWith(SpringRunner.class) to your test, otherwise the annotations will be ignored.
If you are using JUnit 5, there’s 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.
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@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’ll 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 { ... }
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. |
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.
When placed on a top-level class, @TestConfiguration
indicates that classes in src/test/java
should not be picked up by scanning.
You can then import that class explicitly where it is required, as shown in the following example:
@SpringBootTest
@Import(MyTestsConfiguration.class)
class MyTests {
@Test
void exampleTest() {
...
}
}
If you directly use @ComponentScan (that is, not through @SpringBootApplication ) you need to register the TypeExcludeFilter with it.
See the Javadoc for details.
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Using Application Arguments
If your application expects arguments, you can
have @SpringBootTest
inject them using the args
attribute.
@SpringBootTest(args = "--app.test=one")
class ApplicationArgumentsExampleTests {
@Test
void applicationArgumentsPopulated(@Autowired ApplicationArguments args) {
assertThat(args.getOptionNames()).containsOnly("app.test");
assertThat(args.getOptionValues("app.test")).containsOnly("one");
}
}
Testing with a mock environment
By default, @SpringBootTest
does not start the server.
If you have web endpoints that you want to test against this mock environment, you can additionally configure MockMvc
as shown in the following example:
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.servlet.MockMvc;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
@SpringBootTest
@AutoConfigureMockMvc
class MockMvcExampleTests {
@Test
void exampleTest(@Autowired MockMvc mvc) throws Exception {
mvc.perform(get("/")).andExpect(status().isOk()).andExpect(content().string("Hello World"));
}
}
If you want to focus only on the web layer and not start a complete ApplicationContext , consider using @WebMvcTest instead.
|
Alternatively, you can configure a WebTestClient
as shown in the following example:
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.reactive.server.WebTestClient;
@SpringBootTest
@AutoConfigureWebTestClient
class MockWebTestClientExampleTests {
@Test
void exampleTest(@Autowired WebTestClient webClient) {
webClient.get().uri("/").exchange().expectStatus().isOk().expectBody(String.class).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:
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.test.web.reactive.server.WebTestClient;
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class RandomPortWebTestClientExampleTests {
@Test
void exampleTest(@Autowired WebTestClient webClient) {
webClient.get().uri("/").exchange().expectStatus().isOk().expectBody(String.class).isEqualTo("Hello World");
}
}
This setup requires spring-webflux
on the classpath.
If you can’t or won’t add webflux, Spring Boot also provides a TestRestTemplate
facility:
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.boot.test.web.client.TestRestTemplate;
import static org.assertj.core.api.Assertions.assertThat;
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
class RandomPortTestRestTemplateExampleTests {
@Test
void exampleTest(@Autowired TestRestTemplate restTemplate) {
String body = restTemplate.getForObject("/", String.class);
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:
@ExtendWith(SpringExtension.class)
@SpringBootTest(properties = "spring.jmx.enabled=true")
@DirtiesContext
class SampleJmxTests {
@Autowired
private MBeanServer mBeanServer;
@Test
void exampleTest() {
// ...
}
}
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
|
The following example replaces an existing RemoteService
bean with a mock implementation:
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.*;
import org.springframework.boot.test.context.*;
import org.springframework.boot.test.mock.mockito.*;
import static org.assertj.core.api.Assertions.*;
import static org.mockito.BDDMockito.*;
@SpringBootTest
class MyTests {
@MockBean
private RemoteService remoteService;
@Autowired
private Reverser reverser;
@Test
void exampleTest() {
// RemoteService has been injected into the reverser bean
given(this.remoteService.someCall()).willReturn("mock");
String reverse = reverser.reverseSomeCall();
assertThat(reverse).isEqualTo("kcom");
}
}
@MockBean cannot be used to mock the behavior of a bean that’s 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.
CGLib proxies, such as those created for scoped beans, declare the proxied methods as final .
This stops Mockito from functioning correctly as it cannot mock or spy on final methods in its default configuration.
If you want to mock or spy on such a bean, configure Mockito to use its inline mock maker by adding org.mockito:mockito-inline to your application’s test dependencies.
This allows Mockito to mock and spy on final methods.
|
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.
|
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:
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.*;
import org.springframework.boot.test.autoconfigure.json.*;
import org.springframework.boot.test.context.*;
import org.springframework.boot.test.json.*;
import static org.assertj.core.api.Assertions.*;
@JsonTest
class MyJsonTests {
@Autowired
private JacksonTester<VehicleDetails> json;
@Test
void testSerialize() 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 testDeserialize() 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");
}
}
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’re using 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
.
assertThat(json.write(message))
.extractingJsonPathNumberValue("@.test.numberValue")
.satisfies((number) -> assertThat(number.floatValue()).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
, and HandlerMethodArgumentResolver
.
Regular @Component
beans are not scanned when using this annotation.
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 :
|
import org.junit.jupiter.api.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.boot.test.autoconfigure.web.servlet.*;
import org.springframework.boot.test.mock.mockito.*;
import static org.assertj.core.api.Assertions.*;
import static org.mockito.BDDMockito.*;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
@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"));
}
}
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 or Selenium, auto-configuration also provides an HtmlUnit WebClient
bean and/or a Selenium WebDriver
bean.
The following example uses HtmlUnit:
import com.gargoylesoftware.htmlunit.*;
import org.junit.jupiter.api.*;
import org.springframework.beans.factory.annotation.*;
import org.springframework.boot.test.autoconfigure.web.servlet.*;
import org.springframework.boot.test.mock.mockito.*;
import static org.assertj.core.api.Assertions.*;
import static org.mockito.BDDMockito.*;
@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");
}
}
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
beans are not scanned when the @WebFluxTest
annotation is used.
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 :
|
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTest;
import org.springframework.http.MediaType;
import org.springframework.test.web.reactive.server.WebTestClient;
@WebFluxTest(UserVehicleController.class)
class MyControllerTests {
@Autowired
private WebTestClient webClient;
@MockBean
private UserVehicleService userVehicleService;
@Test
void testExample() throws Exception {
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");
}
}
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 via the functional web framework.
For testing RouterFunction beans in the context, consider importing your RouterFunction yourself via @Import or using @SpringBootTest .
|
@WebFluxTest cannot detect custom security configuration registered via a @Bean of type SecurityWebFilterChain .
To include that in your test, you will need to import the configuration that registers the bean via @Import or use @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 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.
Regular @Component
beans are not loaded into the ApplicationContext
.
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:
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
@DataJpaTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class ExampleNonTransactionalTests {
}
Data JPA tests may also inject a TestEntityManager
bean, which provides an alternative to the standard JPA EntityManager
that is specifically designed for tests.
If you want to use TestEntityManager
outside of @DataJpaTest
instances, you can also use the @AutoConfigureTestEntityManager
annotation.
A JdbcTemplate
is also available if you need that.
The following example shows the @DataJpaTest
annotation in use:
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.autoconfigure.orm.jpa.*;
import static org.assertj.core.api.Assertions.*;
@DataJpaTest
class ExampleRepositoryTests {
@Autowired
private TestEntityManager entityManager;
@Autowired
private UserRepository repository;
@Test
void testExample() throws Exception {
this.entityManager.persist(new User("sboot", "1234"));
User user = this.repository.findByUsername("sboot");
assertThat(user.getUsername()).isEqualTo("sboot");
assertThat(user.getVin()).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 ExampleRepositoryTests {
// ...
}
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
beans are not loaded into the ApplicationContext
.
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:
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.autoconfigure.jdbc.JdbcTest;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
@JdbcTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class ExampleNonTransactionalTests {
}
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.
Regular @Component
beans are not loaded into the ApplicationContext
.
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 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", earlier in this chapter.)
Regular @Component
beans are not loaded into the ApplicationContext
.
A list of the auto-configurations that are enabled by @JooqTest can be found in the appendix.
|
@JooqTest
configures a DSLContext
.
Regular @Component
beans are not loaded into the ApplicationContext
.
The following example shows the @JooqTest
annotation in use:
import org.jooq.DSLContext;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.autoconfigure.jooq.JooqTest;
@JooqTest
class ExampleJooqTests {
@Autowired
private 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 an in-memory embedded MongoDB (if available), configures a MongoTemplate
, scans for @Document
classes, and configures Spring Data MongoDB repositories.
Regular @Component
beans are not loaded into the ApplicationContext
.
(For more about using MongoDB with Spring Boot, see "MongoDB", earlier in this chapter.)
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:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.mongo.DataMongoTest;
import org.springframework.data.mongodb.core.MongoTemplate;
@DataMongoTest
class ExampleDataMongoTests {
@Autowired
private MongoTemplate mongoTemplate;
//
}
In-memory embedded MongoDB 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 MongoDB server, you should exclude the embedded MongoDB auto-configuration, as shown in the following example:
import org.springframework.boot.autoconfigure.mongo.embedded.EmbeddedMongoAutoConfiguration;
import org.springframework.boot.test.autoconfigure.data.mongo.DataMongoTest;
@DataMongoTest(excludeAutoConfiguration = EmbeddedMongoAutoConfiguration.class)
class ExampleDataMongoNonEmbeddedTests {
}
Auto-configured Data Neo4j Tests
You can use @DataNeo4jTest
to test Neo4j applications.
By default, it uses an in-memory embedded Neo4j (if the embedded driver is available), scans for @NodeEntity
classes, and configures Spring Data Neo4j repositories.
Regular @Component
beans are not loaded into the ApplicationContext
.
(For more about using Neo4J with Spring Boot, see "Neo4j", earlier in this chapter.)
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:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.neo4j.DataNeo4jTest;
@DataNeo4jTest
class ExampleDataNeo4jTests {
@Autowired
private YourRepository repository;
//
}
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:
import org.springframework.boot.test.autoconfigure.data.neo4j.DataNeo4jTest;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;
@DataNeo4jTest
@Transactional(propagation = Propagation.NOT_SUPPORTED)
class ExampleNonTransactionalTests {
}
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
beans are not loaded into the ApplicationContext
.
(For more about using Redis with Spring Boot, see "Redis", earlier in this chapter.)
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:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.redis.DataRedisTest;
@DataRedisTest
class ExampleDataRedisTests {
@Autowired
private YourRepository repository;
//
}
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
beans are not loaded into the ApplicationContext
.
(For more about using LDAP with Spring Boot, see "LDAP", earlier in this chapter.)
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:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.data.ldap.DataLdapTest;
import org.springframework.ldap.core.LdapTemplate;
@DataLdapTest
class ExampleDataLdapTests {
@Autowired
private 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:
import org.springframework.boot.autoconfigure.ldap.embedded.EmbeddedLdapAutoConfiguration;
import org.springframework.boot.test.autoconfigure.data.ldap.DataLdapTest;
@DataLdapTest(excludeAutoConfiguration = EmbeddedLdapAutoConfiguration.class)
class ExampleDataLdapNonEmbeddedTests {
}
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 adds support for MockRestServiceServer
.
Regular @Component
beans are not loaded into the ApplicationContext
.
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
, as shown in the following example:
@RestClientTest(RemoteVehicleDetailsService.class)
class ExampleRestClientTest {
@Autowired
private RemoteVehicleDetailsService service;
@Autowired
private MockRestServiceServer server;
@Test
void getVehicleDetailsWhenResultIsSuccessShouldReturnDetails()
throws Exception {
this.server.expect(requestTo("/greet/details"))
.andRespond(withSuccess("hello", MediaType.TEXT_PLAIN));
String greeting = this.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.
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:
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;
import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.document;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
@WebMvcTest(UserController.class)
@AutoConfigureRestDocs
class UserDocumentationTests {
@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"));
}
}
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
static class CustomizationConfiguration
implements RestDocsMockMvcConfigurationCustomizer {
@Override
public void customize(MockMvcRestDocumentationConfigurer configurer) {
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)
static class ResultHandlerConfiguration {
@Bean
public RestDocumentationResultHandler restDocumentation() {
return MockMvcRestDocumentation.document("{method-name}");
}
}
Auto-configured Spring REST Docs Tests with WebTestClient
@AutoConfigureRestDocs
can also be used with WebTestClient
.
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:
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.restdocs.AutoConfigureRestDocs;
import org.springframework.boot.test.autoconfigure.web.reactive.WebFluxTest;
import org.springframework.test.web.reactive.server.WebTestClient;
import static org.springframework.restdocs.webtestclient.WebTestClientRestDocumentation.document;
@WebFluxTest
@AutoConfigureRestDocs
class UsersDocumentationTests {
@Autowired
private WebTestClient webTestClient;
@Test
void listUsers() {
this.webTestClient.get().uri("/").exchange().expectStatus().isOk().expectBody()
.consumeWith(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 static class CustomizationConfiguration implements RestDocsWebTestClientConfigurationCustomizer {
@Override
public void customize(WebTestClientRestDocumentationConfigurer configurer) {
configurer.snippets().withEncoding("UTF-8");
}
}
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:
import io.restassured.specification.RequestSpecification;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.restdocs.AutoConfigureRestDocs;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.boot.web.server.LocalServerPort;
import static io.restassured.RestAssured.given;
import static org.hamcrest.Matchers.is;
import static org.springframework.restdocs.restassured3.RestAssuredRestDocumentation.document;
@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
@AutoConfigureRestDocs
class UserDocumentationTests {
@Test
void listUsers(@Autowired RequestSpecification documentationSpec, @LocalServerPort int port) {
given(documentationSpec).filter(document("list-users")).when().port(port).get("/").then().assertThat()
.statusCode(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 static class CustomizationConfiguration implements RestDocsRestAssuredConfigurationCustomizer {
@Override
public void customize(RestAssuredRestDocumentationConfigurer configurer) {
configurer.snippets().withTemplateFormat(TemplateFormats.markdown());
}
}
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 by creating a custom @AutoConfigure…
annotation or simply by adding @ImportAutoConfiguration
to the test as shown in the following example:
@JdbcTest
@ImportAutoConfiguration(IntegrationAutoConfiguration.class)
class ExampleJdbcTests {
}
Make sure to not use the regular @Import annotation to import auto-configurations as they are handled in a specific way by Spring Boot.
|
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 Batch and you rely on the auto-configuration for it.
You could define your @SpringBootApplication
as follows:
@SpringBootApplication
@EnableBatchProcessing
public class SampleApplication { ... }
Because this class is the source configuration for the test, any slice test actually tries to start Spring Batch, 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)
@EnableBatchProcessing
public class BatchConfiguration { ... }
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.
|
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
public class WebConfiguration {
@Bean
public WebMvcConfigurer testConfigurer() {
return new WebMvcConfigurer() {
...
};
}
}
The configuration below will, however, cause the custom WebMvcConfigurer
to be loaded by the test slice.
@Component
public class TestWebMvcConfigurer implements 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", "org.acme.another" })
public class SampleApplication { ... }
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
If you wish to use Spock to test a Spring Boot application, you should add a dependency on Spock’s spock-spring
module to your application’s build.
spock-spring
integrates Spring’s test framework into Spock.
It is recommended that you use Spock 1.2 or later to benefit from a number of improvements to Spock’s Spring Framework and Spring Boot integration.
See the documentation for Spock’s Spring module for further details.
4.25.4. Test Utilities
A few test utility classes that are generally useful when testing your application are packaged as part of spring-boot
.
ConfigFileApplicationContextInitializer
ConfigFileApplicationContextInitializer
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 = ConfigFileApplicationContextInitializer.class)
Using ConfigFileApplicationContextInitializer 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.
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TestPropertyValues
TestPropertyValues
lets you quickly add properties to a ConfigurableEnvironment
or ConfigurableApplicationContext
.
You can call it with key=value
strings, as follows:
TestPropertyValues.of("org=Spring", "name=Boot").applyTo(env);
OutputCapture
OutputCapture
is a JUnit Extension
that you can use to capture System.out
and System.err
output.
To use add @ExtendWith(OutputCaptureExtension.class)
and inject CapturedOutput
as an argument to your test class constructor or test method as follows:
@ExtendWith(OutputCaptureExtension.class)
class OutputCaptureTests {
@Test
void testName(CapturedOutput output) {
System.out.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 behaves in a test-friendly way by not throwing exceptions on server-side errors.
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 4.3.2 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:
public class MyTest {
private TestRestTemplate template = new TestRestTemplate();
@Test
public void testRequest() throws Exception {
HttpHeaders headers = this.template.getForEntity(
"https://myhost.example.com/example", String.class).getHeaders();
assertThat(headers.getLocation()).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 SampleWebClientTests {
@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 Config {
@Bean
RestTemplateBuilder restTemplateBuilder() {
return new RestTemplateBuilder().setConnectTimeout(Duration.ofSeconds(1))
.setReadTimeout(Duration.ofSeconds(1));
}
}
}
4.26. 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>javax.websocket</groupId>
<artifactId>javax.websocket-api</artifactId>
</dependency>
4.27. 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
4.27.1. 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 DetailsResp someWsCall(DetailsReq detailsReq) {
return (DetailsResp) this.webServiceTemplate.marshalSendAndReceive(detailsReq, new SoapActionCallback(ACTION));
}
}
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:
@Bean
public WebServiceTemplate webServiceTemplate(WebServiceTemplateBuilder builder) {
return builder.messageSenders(new HttpWebServiceMessageSenderBuilder()
.setConnectTimeout(5000).setReadTimeout(2000).build()).build();
}
4.28. 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.
A demo project is available to showcase how you can create a starter step-by-step. |
4.28.1. Understanding Auto-configured Beans
Under the hood, auto-configuration is implemented with 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 @Configuration
classes that Spring provides (see the META-INF/spring.factories
file).
4.28.2. Locating Auto-configuration Candidates
Spring Boot checks for the presence of a META-INF/spring.factories
file within your published jar.
The file should list your configuration classes under the EnableAutoConfiguration
key, as shown in the following example:
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ com.mycorp.libx.autoconfigure.LibXAutoConfiguration,\ com.mycorp.libx.autoconfigure.LibXWebAutoConfiguration
Auto-configurations must be loaded that way only.
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 s should be used instead.
|
You can use the @AutoConfigureAfter
or @AutoConfigureBefore
annotations if your configuration needs to be applied in a specific order.
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.
4.28.3. 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:
@Configuration(proxyBeanMethods = false)
// Some conditions
public class MyAutoConfiguration {
// Auto-configured beans
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(EmbeddedAcmeService.class)
static class EmbeddedConfiguration {
@Bean
@ConditionalOnMissingBean
public EmbeddedAcmeService embeddedAcmeService() { ... }
}
}
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:
@Configuration(proxyBeanMethods = false)
public class MyAutoConfiguration {
@Bean
@ConditionalOnMissingBean
public MyService myService() { ... }
}
In the preceding example, the myService
bean is going to be created if no bean of type MyService
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).
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@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.
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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
.
SpEL Expression Conditions
The @ConditionalOnExpression
annotation lets configuration be included based on the result of a SpEL expression.
4.28.4. 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
is usually defined as a field of the test class to gather the base, common configuration.
The following example makes sure that UserServiceAutoConfiguration
is always invoked:
private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
.withConfiguration(AutoConfigurations.of(UserServiceAutoConfiguration.class));
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 Assert4J
.
@Test
void defaultServiceBacksOff() {
this.contextRunner.withUserConfiguration(UserConfiguration.class).run((context) -> {
assertThat(context).hasSingleBean(UserService.class);
assertThat(context).getBean("myUserService").isSameAs(context.getBean(UserService.class));
});
}
@Configuration(proxyBeanMethods = false)
static class UserConfiguration {
@Bean
UserService myUserService() {
return new UserService("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(UserService.class);
assertThat(context.getBean(UserService.class).getName()).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.
@Test
public void autoConfigTest {
ConditionEvaluationReportLoggingListener initializer = new ConditionEvaluationReportLoggingListener(
LogLevel.INFO);
ApplicationContextRunner contextRunner = new ApplicationContextRunner()
.withInitializer(initializer).run((context) -> {
// Do something...
});
}
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 UserService
is not present, the auto-configuration is properly disabled:
@Test
void serviceIsIgnoredIfLibraryIsNotPresent() {
this.contextRunner.withClassLoader(new FilteredClassLoader(UserService.class))
.run((context) -> assertThat(context).doesNotHaveBean("userService"));
}
4.28.5. Creating Your Own Starter
A full Spring Boot starter for a library may contain the following components:
-
The
autoconfigure
module that contains the auto-configuration code. -
The
starter
module that provides a dependency to theautoconfigure
module as well as the library and any additional dependencies that are typically useful. In a nutshell, adding the starter should provide everything needed to start using that library.
You may combine the auto-configuration code and the dependency management in a single module if you do not need to separate those two concerns. |
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-autoconfigure
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 (e.g. 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);
// getters & setters
}
You should only use simple 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, e.g. "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.
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.
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>
With Gradle 4.5 and earlier, the dependency should be declared in the compileOnly
configuration, as shown in the following example:
dependencies {
compileOnly "org.springframework.boot:spring-boot-autoconfigure-processor"
}
With Gradle 4.6 and later, 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 (i.e. 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.
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4.29. 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 via 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.
4.29.1. Requirements
Spring Boot supports Kotlin 1.3.x.
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. |
4.29.2. 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 via 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. |
4.29.3. Kotlin API
runApplication
Spring Boot provides an idiomatic way to run an application with runApplication<MyApplication>(*args)
as shown in the following example:
import org.springframework.boot.autoconfigure.SpringBootApplication
import org.springframework.boot.runApplication
@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.
4.29.4. 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 via 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 via 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.
|
4.29.5. @ConfigurationProperties
@ConfigurationProperties
when used in combination with @ConstructorBinding
supports classes with immutable val
properties as shown in the following example:
@ConstructorBinding
@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.
|
4.29.6. 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 @BeforeClass
and @AfterClass
annotations on non-static methods, which is a good fit for Kotlin.
JUnit 5 is the default and the vintage engine is provided for backward compatibility with JUnit 4.
If you don’t use it, exclude org.junit.vintange:junit-vintage-engine
.
You also need to switch test instance lifecycle to "per-class".
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.
4.29.7. 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
4.29.8. Building Docker Images
Spring Boot applications can be containerized by packaging them into Docker images. A typical Spring Boot fat jar can be converted into a Docker image by adding just a few lines to a Dockerfile that can be used to build the image. However, there are various downsides to copying and running the fat jar as is in the docker image. There’s always a certain amount of overhead when running a fat 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.
Layered Jars
To make it easier to create optimized Docker images that can be built with a dockerfile, Spring Boot supports "layered jars".
A regular fat jar that can be run with java -jar
has the following structure:
META-INF/
MANIFEST.MF
org/
springframework/
boot/
loader/
...
BOOT-INF/
classes/
...
lib/
...
The jar is organized into three main parts:
-
Classes used to bootstrap jar loading
-
Your application classes in
BOOT-INF/classes
-
Dependencies in
BOOT-INF/lib
Instead of the above jar, you can create a layered jar that looks something like this:
META-INF/
MANIFEST.MF
org/
springframework/
boot/
loader/
...
BOOT-INF/
layers/
<name>/
classes/
...
lib/
...
<name>/
classes/
...
lib/
...
layers.idx
You still see the bootstrap loader classes (you can still run java -jar
) but now the lib
and classes
folders have been split up and categorized into layers.
There’s also a layers.idx
file that provides the order in which layers should be added.
Out-of-the-box, the following layers are supported:
-
dependencies
(for regular released dependencies) -
snapshot-dependencies
(for snapshot dependencies) -
resources
(for static resources) -
application
(for application classes and resources)
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.
For Maven, layered jars can be created using a new layout
type called LAYERED_JAR
.
See the layout section for more details.
For Gradle, refer to the packaging layered jars section of the Gradle plugin documentation.
Writing the Dockerfile
When you create a layered jar, the spring-boot-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.
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’s an example of a Dockerfile using jarmode
.
FROM adoptopenjdk:11-jre-hotspot as builder
WORKDIR application
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} application.jar
RUN java -Djarmode=layertools -jar application.jar extract
FROM adoptopenjdk:11-jre-hotspot
WORKDIR application
COPY --from=builder application/dependencies/ ./
COPY --from=builder application/snapshot-dependencies/ ./
COPY --from=builder application/resources/ ./
COPY --from=builder application/application/ ./
ENTRYPOINT ["java", "org.springframework.boot.loader.JarLauncher"]
This is a multi-stage dockerfile.
The builder stage extracts the folders 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.
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.
4.30. What to Read Next
If you want to learn more about any of the classes discussed in this section, you can check out the Spring Boot API documentation or you can browse the source code directly. If you have specific questions, take a look at the how-to section.
If you are comfortable with Spring Boot’s core features, you can continue on and read about production-ready features.
5. Spring Boot Actuator: 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.
5.1. Enabling Production-ready Features
The spring-boot-actuator
module provides all of Spring Boot’s production-ready features.
The simplest way to enable the features is to add a dependency to 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'
}
5.2. 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.
Each individual endpoint can be enabled or disabled.
This controls whether or not the endpoint is created and its bean exists in the application context.
To be remotely accessible an endpoint also has to be exposed via JMX or HTTP.
Most applications choose HTTP, where the ID of the endpoint along with a prefix of /actuator
is mapped to a URL.
For example, by default, the health
endpoint is mapped to /actuator/health
.
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 trace 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 |
|
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 using Spring Session. |
|
Lets the application be gracefully shutdown. Disabled by default. |
|
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 an |
|
Exposes JMX beans over HTTP (when Jolokia is on the classpath, not available for WebFlux).
Requires a dependency on |
|
Returns the contents of the logfile (if |
|
Exposes metrics in a format that can be scraped by a Prometheus server.
Requires a dependency on |
To learn more about the Actuator’s endpoints and their request and response formats, please refer to the separate API documentation (HTML or PDF).
5.2.1. 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
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
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.
|
5.2.2. Exposing Endpoints
Since Endpoints may contain sensitive information, careful consideration should be given about when to expose them. The following table shows the default exposure for the built-in endpoints:
ID | JMX | Web |
---|---|---|
|
Yes |
No |
|
Yes |
No |
|
Yes |
No |
|
Yes |
No |
|
Yes |
No |
|
Yes |
No |
|
Yes |
No |
|
Yes |
Yes |
|
N/A |
No |
|
Yes |
No |
|
Yes |
Yes |
|
Yes |
No |
|
N/A |
No |
|
N/A |
No |
|
Yes |
No |
|
Yes |
No |
|
Yes |
No |
|
Yes |
No |
|
N/A |
No |
|
Yes |
No |
|
Yes |
No |
|
Yes |
No |
|
Yes |
No |
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.
Both include
and exclude
properties can be configured with a list of endpoint IDs.
For example, to stop exposing all endpoints over JMX and only expose the health
and info
endpoints, use the following property:
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
|
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.
|
5.2.3. Securing HTTP Endpoints
You should take care to secure HTTP endpoints in the same way that you would any other sensitive URL.
If Spring Security is present, endpoints are secured by default using Spring Security’s content-negotiation strategy.
If you wish to configure custom security for HTTP endpoints, for example, only allow users with a certain role to access them, Spring Boot provides some convenient RequestMatcher
objects that can be used in combination with Spring Security.
A typical Spring Security configuration might look something like the following example:
@Configuration(proxyBeanMethods = false)
public class ActuatorSecurity extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
http.requestMatcher(EndpointRequest.toAnyEndpoint()).authorizeRequests((requests) ->
requests.anyRequest().hasRole("ENDPOINT_ADMIN"));
http.httpBasic();
}
}
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=*
Additionally, if Spring Security is present, you would need to add custom security configuration that allows unauthenticated access to the endpoints as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class ActuatorSecurity extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
http.requestMatcher(EndpointRequest.toAnyEndpoint()).authorizeRequests((requests) ->
requests.anyRequest().permitAll());
}
}
5.2.4. 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 will cache 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
The prefix management.endpoint.<name> is used to uniquely identify the endpoint that is being configured.
|
When making an authenticated HTTP request, the Principal is considered as input to the endpoint and, therefore, the response will not be cached.
|
5.2.5. 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.
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
, then 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.
5.2.6. 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, Actuator’s web endpoints can be configured to support such scenarios.
CORS support is disabled by default and is only enabled once the management.endpoints.web.cors.allowed-origins
property has been set.
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
See CorsEndpointProperties for a complete list of options. |
5.2.7. 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 using Jersey, Spring MVC, or Spring WebFlux.
If both Jersey and Spring MVC are available, Spring MVC will be used.
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 via their parameters.
When exposed via the web, the values for these parameters are taken from the URL’s query parameters and from the JSON request body.
When exposed via 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 @org.springframework.lang.Nullable
.
Each root property in the JSON request body can be mapped to a parameter of the endpoint. Consider the following JSON request body:
{
"name": "test",
"counter": 42
}
This can be used to invoke a write operation that takes String name
and int counter
parameters.
Because endpoints are technology agnostic, only simple types can be specified in the method signature.
In particular declaring a single parameter with a custom type defining a name and counter properties is not supported.
|
To allow the input to be mapped to the operation method’s parameters, Java code implementing an endpoint should be compiled with -parameters , and Kotlin code implementing an endpoint should be compiled with -java-parameters .
This will happen automatically if you are using Spring Boot’s Gradle plugin or if you are using 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 via JMX or an HTTP request is converted to the required types 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 will be 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 web-exposed endpoints.
The default base path is /actuator
.
For example, an endpoint with the ID sessions
will use /actuator/sessions
as its path in the predicate.
The path can be further customized 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.
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 will not be called and the response status will be 400 (Bad Request).
Web Endpoint Range Requests
An HTTP range request can be used 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 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
@ControllerEndpoint
and @RestControllerEndpoint
can be used to implement an endpoint that is only exposed by Spring MVC or Spring WebFlux.
Methods are mapped 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.
5.2.8. 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 only shown to authorized users.
Authorized roles can be configured 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.
The roles can be configured 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 either be 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.
The HealthContributorRegistry can be used to register and unregister health indicators at runtime.
|
Auto-configured HealthIndicators
The following HealthIndicators
are auto-configured by Spring Boot when appropriate:
Name | Description |
---|---|
Checks that a Cassandra database is up. |
|
Checks that a Couchbase cluster is up. |
|
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. |
|
Checks that a Solr server is up. |
You can disable them all by setting the management.health.defaults.enabled property.
|
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:
import org.springframework.boot.actuate.health.Health;
import org.springframework.boot.actuate.health.HealthIndicator;
import org.springframework.stereotype.Component;
@Component
public class MyHealthIndicator implements HealthIndicator {
@Override
public Health health() {
int errorCode = check(); // perform some specific health check
if (errorCode != 0) {
return Health.down().withDetail("Error Code", errorCode).build();
}
return Health.up().build();
}
}
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 .
|
In addition to Spring Boot’s predefined Status
types, it is also possible for Health
to return a custom Status
that represents a new system state.
In such cases, a custom implementation of the StatusAggregator
interface also needs to be provided, or the default implementation has to be configured by using the management.endpoint.health.status.order
configuration property.
For example, assume a new Status
with code 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
The HTTP status code in the response reflects the overall health status (for example, UP
maps to 200, while OUT_OF_SERVICE
and DOWN
map to 503).
You might also want to register custom status mappings if you access the health endpoint over HTTP.
For example, the following property maps FATAL
to 503 (service unavailable):
management.endpoint.health.status.http-mapping.fatal=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 |
---|---|
DOWN |
SERVICE_UNAVAILABLE (503) |
OUT_OF_SERVICE |
SERVICE_UNAVAILABLE (503) |
UP |
No mapping by default, so http status is 200 |
UNKNOWN |
No mapping by default, so http status is 200 |
Reactive Health Indicators
For reactive applications, such as those using 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, The ReactiveHealthContributorRegistry should be used to register and unregister health indicators at runtime.
If you need to register a regular HealthContributor , you should wrap it using 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() //perform some specific health check that returns a Mono<Health>
.onErrorResume(ex -> Mono.just(new Health.Builder().down(ex).build()));
}
}
To handle the error automatically, consider extending from AbstractReactiveHealthIndicator .
|
Auto-configured ReactiveHealthIndicators
The following ReactiveHealthIndicators
are auto-configured by Spring Boot when appropriate:
Name | Description |
---|---|
Checks that a Cassandra database is up. |
|
Checks that a Couchbase cluster is up. |
|
Checks that a Mongo 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’s sometimes useful to organize health indicators into groups that can be used for different purposes. For example, if you deploy your application to Kubernetes, you may want one different sets of health indicators for your “liveness” and “readiness” probes.
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
You can then check the result by hitting localhost:8080/actuator/health/custom
.
By default groups will inherit the same StatusAggregator
and HttpCodeStatusMapper
settings as the system health, however, these can also be defined on a per-group basis.
It’s also possible to 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
You can use @Qualifier("groupname") if you need to register custom StatusAggregator or HttpCodeStatusMapper beans for use with the group.
|
5.2.9. 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
The following InfoContributor
beans are auto-configured by Spring Boot, when appropriate:
Name | Description |
---|---|
Exposes any key from the |
|
Exposes git information if a |
|
Exposes build information if a |
It is possible to disable them all by setting the management.info.defaults.enabled property.
|
Custom Application Information
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=1.8
info.app.java.target=1.8
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: |
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, the git.branch
, git.commit.id
, and git.commit.time
properties are exposed.
A GitProperties bean is auto-configured if a git.properties file is available at the root of the classpath.
See "Generate git information" for more details.
|
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
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 "Generate build information" 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:
import java.util.Collections;
import org.springframework.boot.actuate.info.Info;
import org.springframework.boot.actuate.info.InfoContributor;
import org.springframework.stereotype.Component;
@Component
public class ExampleInfoContributor implements InfoContributor {
@Override
public void contribute(Info.Builder 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"
}
}
5.3. 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 will be used. |
5.3.1. 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 shown in the following example:
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 .
If management.server.port is configured, management.endpoints.web.base-path is relative to management.server.servlet.context-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
5.3.2. 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 shown in the following example:
management.server.port=8081
On Cloud Foundry, applications only receive requests on port 8080 for both HTTP and TCP routing, by default. If you want to use a custom management port on Cloud Foundry, you will need to explicitly set up the application’s routes to forward traffic to the custom port. |
5.3.3. Configuring Management-specific SSL
When configured to use a custom port, the management server can also be configured 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 shown in the following property settings:
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
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
5.3.4. Customizing the Management Server Address
You can customize the address that the management endpoints are available on 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
5.3.5. Disabling HTTP Endpoints
If you do not want to expose endpoints over HTTP, you can set the management port to -1
, as shown in the following example:
management.server.port=-1
This can be achieved using the management.endpoints.web.exposure.exclude
property as well, as shown in following example:
management.endpoints.web.exposure.exclude=*
5.4. 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 and can be turned on by setting the configuration property spring.jmx.enabled
to true
.
Spring Boot exposes management endpoints as JMX MBeans under the org.springframework.boot
domain by default.
5.4.1. 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
5.4.2. Disabling JMX Endpoints
If you do not want to expose endpoints over JMX, you can set the management.endpoints.jmx.exposure.exclude
property to *
, as shown in the following example:
management.endpoints.jmx.exposure.exclude=*
5.4.3. Using Jolokia for JMX over HTTP
Jolokia is a JMX-HTTP bridge that provides an alternative method of accessing JMX beans.
To use Jolokia, include a dependency to org.jolokia:jolokia-core
.
For example, with Maven, you would add the following dependency:
<dependency>
<groupId>org.jolokia</groupId>
<artifactId>jolokia-core</artifactId>
</dependency>
The Jolokia endpoint can then be exposed by adding jolokia
or *
to the management.endpoints.web.exposure.include
property.
You can then access it by using /actuator/jolokia
on your management HTTP server.
Customizing Jolokia
Jolokia has a number of settings that you would traditionally configure by setting servlet parameters.
With Spring Boot, you can use your application.properties
file.
To do so, prefix the parameter with management.endpoint.jolokia.config.
, as shown in the following example:
management.endpoint.jolokia.config.debug=true
5.5. 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.
5.5.1. Configure a Logger
To configure a given logger, POST
a partial entity to the resource’s URI, as shown in the following example:
{
"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 .
|
5.6. 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, please refer to its reference documentation, in particular the concepts section. |
5.6.1. 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. For example, to disable Datadog:
management.metrics.export.datadog.enabled=false
Spring Boot will also add 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
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:
@Bean
MeterRegistryCustomizer<MeterRegistry> metricsCommonTags() {
return registry -> registry.config().commonTags("region", "us-east-1");
}
You can apply customizations to particular registry implementations by being more specific about the generic type:
@Bean
MeterRegistryCustomizer<GraphiteMeterRegistry> graphiteMetricsNamingConvention() {
return registry -> registry.config().namingConvention(MY_CUSTOM_CONVENTION);
}
With that setup in place you can inject MeterRegistry
in your components and register metrics:
@Component
public class SampleBean {
private final Counter counter;
public SampleBean(MeterRegistry registry) {
this.counter = registry.counter("received.messages");
}
public void handleMessage(String message) {
this.counter.increment();
// handle message implementation
}
}
Spring Boot also configures built-in instrumentation (i.e. MeterBinder
implementations) that you can control via configuration or dedicated annotation markers.
5.6.2. Supported monitoring systems
AppOptics
By default, the AppOptics registry pushes metrics to api.appoptics.com/v1/measurements
periodically.
To export metrics to SaaS AppOptics, your API token must be provided:
management.metrics.export.appoptics.api-token=YOUR_TOKEN
Atlas
By default, metrics are exported to Atlas running on your local machine. The location of the Atlas server to use can be provided using:
management.metrics.export.atlas.uri=https://atlas.example.com:7101/api/v1/publish
Datadog
Datadog registry pushes metrics to datadoghq periodically. To export metrics to Datadog, your API key must be provided:
management.metrics.export.datadog.api-key=YOUR_KEY
You can also change the interval at which metrics are sent to Datadog:
management.metrics.export.datadog.step=30s
Dynatrace
Dynatrace registry pushes metrics to the configured URI periodically. To export metrics to Dynatrace, your API token, device ID, and URI must be provided:
management.metrics.export.dynatrace.api-token=YOUR_TOKEN
management.metrics.export.dynatrace.device-id=YOUR_DEVICE_ID
management.metrics.export.dynatrace.uri=YOUR_URI
You can also change the interval at which metrics are sent to Dynatrace:
management.metrics.export.dynatrace.step=30s
Elastic
By default, metrics are exported to Elastic running on your local machine. The location of the Elastic server to use can be provided using the following property:
management.metrics.export.elastic.host=https://elastic.example.com:8086
Ganglia
By default, metrics are exported to Ganglia running on your local machine. The Ganglia server host and port to use can be provided using:
management.metrics.export.ganglia.host=ganglia.example.com
management.metrics.export.ganglia.port=9649
Graphite
By default, metrics are exported to Graphite running on your local machine. The Graphite server host and port to use can be provided using:
management.metrics.export.graphite.host=graphite.example.com
management.metrics.export.graphite.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 behaviour, define your GraphiteMeterRegistry and supply your own HierarchicalNameMapper .
An auto-configured GraphiteConfig and Clock beans are provided unless you define your own:
|
@Bean
public GraphiteMeterRegistry graphiteMeterRegistry(GraphiteConfig config, Clock clock) {
return new GraphiteMeterRegistry(config, clock, MY_HIERARCHICAL_MAPPER);
}
Humio
By default, the Humio registry pushes metrics to cloud.humio.com periodically. To export metrics to SaaS Humio, your API token must be provided:
management.metrics.export.humio.api-token=YOUR_TOKEN
You should also configure one or more tags to identify the data source to which metrics will be pushed:
management.metrics.export.humio.tags.alpha=a
management.metrics.export.humio.tags.bravo=b
Influx
By default, metrics are exported to Influx running on your local machine. The location of the Influx server to use can be provided using:
management.metrics.export.influx.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.
The domain to use can be provided using:
management.metrics.export.jmx.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 behaviour, define your JmxMeterRegistry and supply your own HierarchicalNameMapper .
An auto-configured JmxConfig and Clock beans are provided unless you define your own:
|
@Bean
public JmxMeterRegistry jmxMeterRegistry(JmxConfig config, Clock clock) {
return new JmxMeterRegistry(config, clock, MY_HIERARCHICAL_MAPPER);
}
KairosDB
By default, metrics are exported to KairosDB running on your local machine. The location of the KairosDB server to use can be provided using:
management.metrics.export.kairos.uri=https://kairosdb.example.com:8080/api/v1/datapoints
New Relic
New Relic registry pushes metrics to New Relic periodically. To export metrics to New Relic, your API key and account id must be provided:
management.metrics.export.newrelic.api-key=YOUR_KEY
management.metrics.export.newrelic.account-id=YOUR_ACCOUNT_ID
You can also change the interval at which metrics are sent to New Relic:
management.metrics.export.newrelic.step=30s
Prometheus
Prometheus expects to scrape or poll individual app instances for metrics.
Spring Boot provides an actuator endpoint available at /actuator/prometheus
to present a Prometheus scrape with the appropriate format.
The endpoint is not available by default and must be exposed, see exposing endpoints for more details. |
Here is an example scrape_config
to add to prometheus.yml
:
scrape_configs:
- job_name: 'spring'
metrics_path: '/actuator/prometheus'
static_configs:
- targets: ['HOST:PORT']
For ephemeral or batch jobs which may not exist long enough to be scraped, Prometheus Pushgateway support can be used to expose their 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, Spring Boot auto-configures a PrometheusPushGatewayManager
bean.
This manages the pushing of metrics to a Prometheus Pushgateway.
The PrometheusPushGatewayManager
can be tuned using properties under management.metrics.export.prometheus.pushgateway
.
For advanced configuration, you can also provide your own PrometheusPushGatewayManager
bean.
SignalFx
SignalFx registry pushes metrics to SignalFx periodically. To export metrics to SignalFx, your access token must be provided:
management.metrics.export.signalfx.access-token=YOUR_ACCESS_TOKEN
You can also change the interval at which metrics are sent to SignalFx:
management.metrics.export.signalfx.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 allows you to see what metrics are collected in the metrics endpoint.
The in-memory backend disables itself as soon as you’re using any of the other available backend. You can also disable it explicitly:
management.metrics.export.simple.enabled=false
Stackdriver
Stackdriver registry pushes metrics to Stackdriver periodically. To export metrics to SaaS Stackdriver, your Google Cloud project id must be provided:
management.metrics.export.stackdriver.project-id=my-project
You can also change the interval at which metrics are sent to Stackdriver:
management.metrics.export.stackdriver.step=30s
StatsD
The StatsD registry pushes metrics over UDP to a StatsD agent eagerly. By default, metrics are exported to a StatsD agent running on your local machine. The StatsD agent host and port to use can be provided using:
management.metrics.export.statsd.host=statsd.example.com
management.metrics.export.statsd.port=9125
You can also change the StatsD line protocol to use (default to Datadog):
management.metrics.export.statsd.flavor=etsy
Wavefront
Wavefront registry pushes metrics to Wavefront periodically. If you are exporting metrics to Wavefront directly, your API token must be provided:
management.metrics.export.wavefront.api-token=YOUR_API_TOKEN
Alternatively, you may use a Wavefront sidecar or an internal proxy set up in your environment that forwards metrics data to the Wavefront API host:
management.metrics.export.wavefront.uri=proxy://localhost:2878
If publishing metrics to a Wavefront proxy (as described in the 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.metrics.export.wavefront.step=30s
5.6.3. Supported Metrics
Spring Boot registers the following core metrics when applicable:
-
JVM metrics, report utilization of:
-
Various memory and buffer pools
-
Statistics related to garbage collection
-
Threads utilization
-
Number of classes loaded/unloaded
-
-
CPU metrics
-
File descriptor metrics
-
Kafka consumer metrics (JMX support should be enabled)
-
Log4j2 metrics: record the number of events logged to Log4j2 at each level
-
Logback metrics: record the number of events logged to Logback at each level
-
Uptime metrics: report a gauge for uptime and a fixed gauge representing the application’s absolute start time
-
Tomcat metrics (
server.tomcat.mbeanregistry.enabled
must be set totrue
for all Tomcat metrics to be registered) -
Spring Integration metrics
Spring MVC Metrics
Auto-configuration enables the instrumentation of requests handled by Spring MVC.
When management.metrics.web.server.request.autotime.enabled
is true
, this instrumentation occurs for all requests.
Alternatively, when set to false
, you can enable instrumentation by adding @Timed
to a request-handling method:
@RestController
@Timed (1)
public class MyController {
@GetMapping("/api/people")
@Timed(extraTags = { "region", "us-east-1" }) (2)
@Timed(value = "all.people", longTask = true) (3)
public List<Person> listPeople() { ... }
}
1 | A controller class to enable timings on every request handler in the controller. |
2 | A method to enable for an individual endpoint. This is not necessary if you have it on the class, but can be used to further customize the timer for this particular endpoint. |
3 | A method with longTask = true to enable 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, metrics are generated with the name, http.server.requests
.
The name can be customized by setting the management.metrics.web.server.request.metric-name
property.
By default, Spring MVC-related metrics are tagged with the following information:
Tag | Description |
---|---|
|
Simple class name of any exception that was thrown while handling the request. |
|
Request’s method (for example, |
|
Request’s outcome based on the status code of the response.
1xx is |
|
Response’s HTTP status code (for example, |
|
Request’s URI template prior to variable substitution, if possible (for example, |
To customize the tags, provide a @Bean
that implements WebMvcTagsProvider
.
Spring WebFlux Metrics
Auto-configuration enables the instrumentation of all requests handled by 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.metrics.web.server.request.metric-name
property.
By default, WebFlux-related metrics are tagged with the following information:
Tag | Description |
---|---|
|
Simple class name of any exception that was thrown while handling the request. |
|
Request’s method (for example, |
|
Request’s outcome based on the status code of the response.
1xx is |
|
Response’s HTTP status code (for example, |
|
Request’s URI template prior to variable substitution, if possible (for example, |
To customize the tags, provide a @Bean
that implements WebFluxTagsProvider
.
Jersey Server Metrics
When Micrometer’s micrometer-jersey2
module is on the classpath, auto-configuration enables the instrumentation of requests handled by the Jersey JAX-RS implementation.
When management.metrics.web.server.request.autotime.enabled
is true
, this instrumentation occurs for all requests.
Alternatively, when set to false
, you can enable instrumentation by adding @Timed
to a request-handling method:
@Component
@Path("/api/people")
@Timed (1)
public class Endpoint {
@GET
@Timed(extraTags = { "region", "us-east-1" }) (2)
@Timed(value = "all.people", longTask = true) (3)
public List<Person> listPeople() { ... }
}
1 | On a resource class to enable timings on every request handler in the resource. |
2 | On a method to enable for an individual endpoint. This is not necessary if you have it on the class, but can be used to further customize the timer for this particular endpoint. |
3 | On a method with longTask = true to enable 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, metrics are generated with the name, http.server.requests
.
The name can be customized by setting the management.metrics.web.server.request.metric-name
property.
By default, Jersey server metrics are tagged with the following information:
Tag | Description |
---|---|
|
Simple class name of any exception that was thrown while handling the request. |
|
Request’s method (for example, |
|
Request’s outcome based on the status code of the response.
1xx is |
|
Response’s HTTP status code (for example, |
|
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 both RestTemplate
and WebClient
.
For that, you have to get injected with an auto-configured builder and use it to create instances:
-
RestTemplateBuilder
forRestTemplate
-
WebClient.Builder
forWebClient
It is also possible to apply manually the customizers responsible for this instrumentation, namely MetricsRestTemplateCustomizer
and MetricsWebClientCustomizer
.
By default, metrics are generated with the name, http.client.requests
.
The name can be customized by setting the management.metrics.web.client.request.metric-name
property.
By default, metrics generated by an instrumented client are tagged with the following information:
Tag | Description |
---|---|
|
Host portion of the URI |
|
Request’s method (for example, |
|
Request’s outcome based on the status code of the response.
1xx is |
|
Response’s HTTP status code if available (for example, |
|
Request’s URI template prior to variable substitution, if possible (for example, |
To customize the tags, and depending on your choice of client, you can provide a @Bean
that implements RestTemplateExchangeTagsProvider
or WebClientExchangeTagsProvider
.
There are convenience static functions in RestTemplateExchangeTags
and WebClientExchangeTags
.
Cache Metrics
Auto-configuration enables the instrumentation of all available Cache
s 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:
-
Caffeine
-
EhCache 2
-
Hazelcast
-
Any compliant JCache (JSR-107) implementation
Metrics are tagged by the name of the cache and by the name of the CacheManager
that 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, e.g. 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.
|
DataSource Metrics
Auto-configuration enables the instrumentation of all available DataSource
objects with metrics prefixed with jdbc.connections
.
Data source instrumentation results in gauges representing 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 isn’t supported out of the box.
See DataSourcePoolMetadataProvidersConfiguration for examples.
|
Also, Hikari-specific metrics are exposed with a hikaricp
prefix.
Each metric is tagged by the name of the Pool (can be controlled with spring.datasource.name
).
Hibernate Metrics
Auto-configuration enables the instrumentation of all available Hibernate EntityManagerFactory
instances that have statistics enabled with a metric named hibernate
.
Metrics are also tagged by the name of the EntityManagerFactory
that 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
as shown in the following example:
spring.jpa.properties.hibernate.generate_statistics=true
5.6.4. Registering custom metrics
To register custom metrics, inject MeterRegistry
into your component, as shown in the following example:
class Dictionary {
private final List<String> words = new CopyOnWriteArrayList<>();
Dictionary(MeterRegistry registry) {
registry.gaugeCollectionSize("dictionary.size", Tags.empty(), this.words);
}
// …
}
If you find that you repeatedly instrument a suite of metrics across components or applications, you may encapsulate this suite in a MeterBinder
implementation.
By default, metrics from all MeterBinder
beans will be automatically bound to the Spring-managed MeterRegistry
.
5.6.5. Customizing individual metrics
If you need to apply customizations to specific Meter
instances you can use the io.micrometer.core.instrument.config.MeterFilter
interface.
By default, all MeterFilter
beans will be automatically applied to the micrometer MeterRegistry.Config
.
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:
@Bean
public MeterFilter renameRegionTagMeterFilter() {
return MeterFilter.renameTag("com.example", "mytag.region", "mytag.area");
}
Common tags
Common tags are generally used for dimensional drill-down on the operating environment like host, instance, region, stack, etc. Commons tags are applied to all meters and can be configured as shown in the following example:
management.metrics.tags.region=us-east-1
management.metrics.tags.stack=prod
The example above adds region
and stack
tags to all meters with a value of us-east-1
and prod
respectively.
The order of common tags is important if you are using Graphite.
As the order of common tags cannot be guaranteed using this approach, Graphite users are advised to define a custom MeterFilter instead.
|
Per-meter properties
In addition to MeterFilter
beans, it’s also possible to apply a limited set of customization on a per-meter basis using properties.
Per-meter customizations apply to any all meter IDs that start with the given name.
For example, the following will disable any meters that have an ID starting with example.remote
management.metrics.enable.example.remote=false
The following properties allow per-meter customization:
Property | Description |
---|---|
|
Whether to deny meters from emitting any metrics. |
|
Whether to publish a histogram suitable for computing aggregable (across dimension) percentile approximations. |
|
Publish less histogram buckets by clamping the range of expected values. |
|
Publish percentile values computed in your application |
|
Publish a cumulative histogram with buckets defined by your SLAs. |
For more details on concepts behind percentiles-histogram
, percentiles
and sla
refer to the "Histograms and percentiles" section of the micrometer documentation.
5.6.6. Metrics endpoint
Spring Boot provides a metrics
endpoint that can be used 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, e.g. /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 it is shipped to.
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, e.g. /actuator/metrics/jvm.memory.max?tag=area:nonheap
.
The reported measurements are the sum of the statistics of all meters matching the meter name and any tags that have been applied.
So in the example above, the returned "Value" statistic is the sum of the maximum memory footprints of "Code Cache", "Compressed Class Space", and "Metaspace" areas of the heap.
If you just wanted to see the maximum size for the "Metaspace", you could add an additional |
5.7. 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.
Auditing can be enabled 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.
5.7.1. 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
).
5.8. HTTP Tracing
HTTP Tracing can be enabled by providing a bean of type HttpTraceRepository
in your application’s configuration.
For convenience, Spring Boot offers an InMemoryHttpTraceRepository
that stores traces for the last 100 request-response exchanges, by default.
InMemoryHttpTraceRepository
is limited compared to other tracing solutions and we recommend using it only for development environments.
For production environments, use of a production-ready tracing or observability solution, such as Zipkin or Spring Cloud Sleuth, is recommended.
Alternatively, create your own HttpTraceRepository
that meets your needs.
The httptrace
endpoint can be used to obtain information about the request-response exchanges that are stored in the HttpTraceRepository
.
5.9. 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 containing the application PID (by default, in the application directory with a file name ofapplication.pid
). -
WebServerPortFileWriter
creates a file (or files) containing 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:
5.9.1. Extending Configuration
In the META-INF/spring.factories
file, you can activate the listener(s) that writes a PID file, as shown in the following example:
org.springframework.context.ApplicationListener=\ org.springframework.boot.context.ApplicationPidFileWriter,\ org.springframework.boot.web.context.WebServerPortFileWriter
5.10. 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 may include full health information instead of the typical “running” or “stopped” status.
The /cloudfoundryapplication path is not directly accessible to regular users.
In order to use the endpoint, a valid UAA token must be passed with the request.
|
5.10.1. 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
5.10.2. 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
5.10.3. Custom context path
If the server’s context-path has been configured to anything other than /
, the Cloud Foundry endpoints will not be available at the root of the application.
For example, if server.servlet.context-path=/app
, Cloud Foundry endpoints will be 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 will need to explicitly configure that in your application.
The configuration will differ depending on the web server in use.
For Tomcat, the following configuration can be added:
@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 (c, 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("/*");
};
}
5.11. 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.
6. 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 container images (such as Docker), or to virtual/real machines.
This section covers some of the more common deployment scenarios.
6.1. Deploying to Containers
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. The simplest way to run an unpacked archive is by starting the appropriate launcher, as follows:
$ jar -xf myapp.jar $ java org.springframework.boot.loader.JarLauncher
This is actually slightly faster on startup (depending on the size of the jar) than running from an unexploded archive. At runtime you shouldn’t 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
More efficient container images can also be created by copying the dependencies to the image as a separate layer from the application classes and resources (which normally change more frequently).
There is more than one way to achieve this layer separation.
For example, using a Dockerfile
you could express it in this form:
FROM openjdk:8-jdk-alpine AS builder WORKDIR target/dependency ARG APPJAR=target/*.jar COPY ${APPJAR} app.jar RUN jar -xf ./app.jar FROM openjdk:8-jre-alpine VOLUME /tmp ARG DEPENDENCY=target/dependency COPY --from=builder ${DEPENDENCY}/BOOT-INF/lib /app/lib COPY --from=builder ${DEPENDENCY}/META-INF /app/META-INF COPY --from=builder ${DEPENDENCY}/BOOT-INF/classes /app ENTRYPOINT ["java","-cp","app:app/lib/*","com.example.MyApplication"]
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 APPJAR=path/to/myapp.jar .
6.2. 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 simple application that we developed in the “Getting Started” section up and running in the Cloud.
6.2.1. 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 1.8.0_121 from https://java-buildpack.cloudfoundry.org/openjdk/trusty/x86_64/openjdk-1.8.0_121.tar.gz (found in cache) 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: $VCAP_SERVICES
).
This architecture decision is due to Cloud Foundry’s polyglot (any language and platform can be supported as a buildpack) nature.
Process-scoped environment variables are language agnostic.
Environment variables do not always make for the easiest API, so Spring Boot automatically extracts them and flattens the data into properties that can be accessed through Spring’s Environment
abstraction, as shown in the following example:
@Component
class MyBean implements EnvironmentAware {
private String instanceId;
@Override
public void setEnvironment(Environment environment) {
this.instanceId = environment.getProperty("vcap.application.instance_id");
}
// ...
}
All Cloud Foundry properties are prefixed with vcap
.
You can use vcap
properties to access application information (such as the public URL of the application) and service information (such as database credentials).
See the ‘CloudFoundryVcapEnvironmentPostProcessor’ Javadoc for complete details.
The Java CFEnv project is a better fit for tasks such as configuring a DataSource. |
6.2.2. Heroku
Heroku is another popular PaaS platform.
To customize Heroku builds, you provide a Procfile
, which provides the incantation required to deploy an application.
Heroku assigns a port
for the Java application to use and then ensures that routing to the external URI works.
You must configure your application to listen on the correct port.
The following example shows the Procfile
for our starter REST application:
web: java -Dserver.port=$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 master 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 1.8... done -----> Installing Maven 3.3.1... 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] master -> master
Your application should now be up and running on Heroku. For more details, refer to Deploying Spring Boot Applications to Heroku.
6.2.3. OpenShift
OpenShift is the Red Hat public (and enterprise) extension of the Kubernetes container orchestration platform. Similarly to Kubernetes, OpenShift has many options for installing Spring Boot based applications.
OpenShift has many resources describing how to deploy Spring Boot applications, including:
6.2.4. 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 only the simplest option: 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.
6.2.5. Boxfuse and Amazon Web Services
Boxfuse 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. Boxfuse 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. Boxfuse 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 Boxfuse account, connected it to your AWS account, installed the latest version of the Boxfuse 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, Boxfuse activates a Spring profile named boxfuse on startup.
If your executable jar or war contains an application-boxfuse.properties file, Boxfuse bases its configuration on the properties it contains.
|
At this point, boxfuse
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 Boxfuse Spring Boot integration to get started with a Maven build to run the app.
6.2.6. 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 run in App Engine, you can create a project in the UI first, which sets up a unique identifier for you and also sets up HTTP routes. Add a Java app to the project and leave it empty and then use the Google Cloud SDK to push your Spring Boot app into that slot from the command line or CI build.
App Engine Standard requires you to use WAR packaging. Follow these steps to deploy App Engine Standard application to Google Cloud.
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: java
env: flex
runtime_config:
jdk: openjdk8
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>1.3.0</version>
<configuration>
<project>myproject</project>
</configuration>
</plugin>
Then deploy with mvn appengine:deploy
(if you need to authenticate first, the build fails).
6.3. Installing Spring Boot Applications
In addition to running Spring Boot applications by using java -jar
, it is also possible to make fully executable applications for Unix systems.
A fully executable jar can be executed like any other executable binary or it can be registered with init.d
or systemd
.
This makes it very easy to install and manage Spring Boot applications in common production environments.
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:
bootJar {
launchScript()
}
You can then run your application by typing ./my-application.jar
(where my-application
is the name of your artifact).
The directory containing the jar is used as your application’s working directory.
6.3.1. Supported Operating Systems
The default script 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 embeddedLaunchScript
.
6.3.2. Unix/Linux Services
Spring Boot application can be easily started as Unix/Linux services by using either init.d
or systemd
.
Installation as an init.d
Service (System V)
If you configured Spring Boot’s Maven or Gradle plugin to generate a fully executable jar, and you do not use a custom embeddedLaunchScript
, your application can be used as an init.d
service.
To do so, symlink the jar to init.d
to support the standard start
, stop
, restart
, and status
commands.
The script 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’s 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
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.
Although you can continue to use init.d
scripts with systemd
, it is also possible to launch Spring Boot applications by using systemd
‘service’ scripts.
Assuming that you have a Spring Boot application installed in /var/myapp
, to install a Spring Boot application 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 [Service] User=myapp ExecStart=/var/myapp/myapp.jar SuccessExitStatus=143 [Install] WantedBy=multi-user.target
Remember to change the Description , User , 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.
|
Note that, unlike when running as an init.d
service, 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
Refer to man systemctl
for more details.
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. |
|
|
|
The |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Single-line version of |
|
|
|
|
|
|
|
|
|
|
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 |
||
|
Default value for |
||
|
Default value for |
||
|
Default value for |
||
|
Default value for the name of the PID file in |
||
|
Whether the |
|
|
|
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.
6.3.3. 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.
6.4. What to Read Next
Check out 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 Spring Boot CLI, or you can jump ahead to read about build tool plugins.
7. Spring Boot CLI
The Spring Boot CLI is a command line tool that you can use if you want to quickly develop a Spring application. It lets you run Groovy scripts, which means that you have a familiar Java-like syntax without so much boilerplate code. You can also bootstrap a new project or write your own command for it.
7.1. 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.
7.2. 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 simple help screen is displayed, as follows:
$ spring usage: spring [--help] [--version] <command> [<args>] Available commands are: run [options] <files> [--] [args] Run a spring groovy script ... more command help is shown here
You can type spring help
to get more details about any of the supported commands, as shown in the following example:
$ spring help run spring run - Run a spring groovy script usage: spring run [options] <files> [--] [args] Option Description ------ ----------- --autoconfigure [Boolean] Add autoconfigure compiler transformations (default: true) --classpath, -cp Additional classpath entries --no-guess-dependencies Do not attempt to guess dependencies --no-guess-imports Do not attempt to guess imports -q, --quiet Quiet logging -v, --verbose Verbose logging of dependency resolution --watch Watch the specified file for changes
The version
command provides a quick way to check which version of Spring Boot you are using, as follows:
$ spring version Spring CLI v2.3.0.M2
7.2.1. Running Applications with the CLI
You can compile and run Groovy source code by using the run
command.
The Spring Boot CLI is completely self-contained, so you do not need any external Groovy installation.
The following example shows a “hello world” web application written in Groovy:
@RestController
class WebApplication {
@RequestMapping("/")
String home() {
"Hello World!"
}
}
To compile and run the application, type the following command:
$ spring run hello.groovy
To pass command-line arguments to the application, use --
to separate the commands from the “spring” command arguments, as shown in the following example:
$ spring run hello.groovy -- --server.port=9000
To set JVM command line arguments, you can use the JAVA_OPTS
environment variable, as shown in the following example:
$ JAVA_OPTS=-Xmx1024m spring run hello.groovy
When setting JAVA_OPTS on Microsoft Windows, make sure to quote the entire instruction, such as set "JAVA_OPTS=-Xms256m -Xmx2048m" .
Doing so ensures the values are properly passed to the process.
|
Deduced “grab” Dependencies
Standard Groovy includes a @Grab
annotation, which lets you declare dependencies on third-party libraries.
This useful technique lets Groovy download jars in the same way as Maven or Gradle would but without requiring you to use a build tool.
Spring Boot extends this technique further and tries to deduce which libraries to “grab” based on your code.
For example, since the WebApplication
code shown previously uses @RestController
annotations, Spring Boot grabs "Tomcat" and "Spring MVC".
The following items are used as “grab hints”:
Items | Grabs |
---|---|
|
JDBC Application. |
|
JMS Application. |
|
Caching abstraction. |
|
JUnit. |
|
RabbitMQ. |
extends |
Spock test. |
|
Spring Batch. |
|
Spring Integration. |
|
Spring MVC + Embedded Tomcat. |
|
Spring Security. |
|
Spring Transaction Management. |
See subclasses of CompilerAutoConfiguration in the Spring Boot CLI source code to understand exactly how customizations are applied.
|
Deduced “grab” Coordinates
Spring Boot extends Groovy’s standard @Grab
support by letting you specify a dependency without a group or version (for example, @Grab('freemarker')
).
Doing so consults Spring Boot’s default dependency metadata to deduce the artifact’s group and version.
The default metadata is tied to the version of the CLI that you use. It changes only when you move to a new version of the CLI, putting you in control of when the versions of your dependencies may change. A table showing the dependencies and their versions that are included in the default metadata can be found in the appendix. |
Default Import Statements
To help reduce the size of your Groovy code, several import
statements are automatically included.
Notice how the preceding example refers to @Component
, @RestController
, and @RequestMapping
without needing to use fully-qualified names or import
statements.
Many Spring annotations work without using import statements.
Try running your application to see what fails before adding imports.
|
Automatic Main Method
Unlike the equivalent Java application, you do not need to include a public static void main(String[] args)
method with your Groovy
scripts.
A SpringApplication
is automatically created, with your compiled code acting as the source
.
Custom Dependency Management
By default, the CLI uses the dependency management declared in spring-boot-dependencies
when resolving @Grab
dependencies.
Additional dependency management, which overrides the default dependency management, can be configured by using the @DependencyManagementBom
annotation.
The annotation’s value should specify the coordinates (groupId:artifactId:version
) of one or more Maven BOMs.
For example, consider the following declaration:
@DependencyManagementBom("com.example.custom-bom:1.0.0")
The preceding declaration picks up custom-bom-1.0.0.pom
in a Maven repository under com/example/custom-versions/1.0.0/
.
When you specify multiple BOMs, they are applied in the order in which you declare them, as shown in the following example:
@DependencyManagementBom(["com.example.custom-bom:1.0.0",
"com.example.another-bom:1.0.0"])
The preceding example indicates that the dependency management in another-bom
overrides the dependency management in custom-bom
.
You can use @DependencyManagementBom
anywhere that you can use @Grab
.
However, to ensure consistent ordering of the dependency management, you can use @DependencyManagementBom
at most once in your application.
7.2.2. Applications with Multiple Source Files
You can use “shell globbing” with all commands that accept file input. Doing so lets you use multiple files from a single directory, as shown in the following example:
$ spring run *.groovy
7.2.3. Packaging Your Application
You can use the jar
command to package your application into a self-contained executable jar file, as shown in the following example:
$ spring jar my-app.jar *.groovy
The resulting jar contains the classes produced by compiling the application and all of the application’s dependencies so that it can then be run by using java -jar
.
The jar file also contains entries from the application’s classpath.
You can add and remove explicit paths to the jar by using --include
and --exclude
.
Both are comma-separated, and both accept prefixes, in the form of “+” and “-”, to signify that they should be removed from the defaults.
The default includes are as follows:
public/**, resources/**, static/**, templates/**, META-INF/**, *
The default excludes are as follows:
.*, repository/**, build/**, target/**, **/*.jar, **/*.groovy
Type spring help jar
on the command line for more information.
7.2.4. 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 8 and war
packaging:
$ spring init --build=gradle --java-version=1.8 --dependencies=websocket --packaging=war sample-app.zip Using service at https://start.spring.io Content saved to 'sample-app.zip'
7.2.5. 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 (v2.3.0.M2) 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 v2.3.0.M2
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
.
7.2.6. Adding Extensions to the CLI
You can add extensions to the CLI by using the install
command.
The command takes one or more sets of artifact coordinates in the format group:artifact:version
, as shown in the following example:
$ spring install com.example:spring-boot-cli-extension:1.0.0.RELEASE
In addition to installing the artifacts identified by the coordinates you supply, all of the artifacts' dependencies are also installed.
To uninstall a dependency, use the uninstall
command.
As with the install
command, it takes one or more sets of artifact coordinates in the format of group:artifact:version
, as shown in the following example:
$ spring uninstall com.example:spring-boot-cli-extension:1.0.0.RELEASE
It uninstalls the artifacts identified by the coordinates you supply and their dependencies.
To uninstall all additional dependencies, you can use the --all
option, as shown in the following example:
$ spring uninstall --all
7.3. Developing Applications with the Groovy Beans DSL
Spring Framework 4.0 has native support for a beans{}
“DSL” (borrowed from Grails), and you can embed bean definitions in your Groovy application scripts by using the same format.
This is sometimes a good way to include external features like middleware declarations, as shown in the following example:
@Configuration(proxyBeanMethods = false)
class Application implements CommandLineRunner {
@Autowired
SharedService service
@Override
void run(String... args) {
println service.message
}
}
import my.company.SharedService
beans {
service(SharedService) {
message = "Hello World"
}
}
You can mix class declarations with beans{}
in the same file as long as they stay at the top level, or, if you prefer, you can put the beans DSL in a separate file.
7.4. Configuring the CLI with settings.xml
The Spring Boot CLI uses Aether, Maven’s dependency resolution engine, to resolve dependencies.
The CLI makes use of the Maven configuration found in ~/.m2/settings.xml
to configure Aether.
The following configuration settings are honored by the CLI:
-
Offline
-
Mirrors
-
Servers
-
Proxies
-
Profiles
-
Activation
-
Repositories
-
-
Active profiles
See Maven’s settings documentation for further information.
7.5. What to Read Next
There are some sample groovy scripts available from the GitHub repository that you can use to try out the Spring Boot CLI. There is also extensive Javadoc throughout the source code.
If you find that you reach the limit of the CLI tool, you probably want to look at converting your application to a full Gradle or Maven built “Groovy project”. The next section covers Spring Boot’s "Build tool plugins", which you can use with Gradle or Maven.
8. 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 “Using Spring Boot” section first.
8.1. 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 3.2 (or later).
See the Spring Boot Maven Plugin Documentation for complete plugin documentation. |
8.1.1. Including the Plugin
To use the Spring Boot Maven Plugin, include the appropriate XML in the plugins
section of your pom.xml
, as shown in the following example:
<?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>
<!-- ... -->
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>2.3.0.M2</version>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
The preceding configuration repackages a jar or war that is built during the package
phase of the Maven lifecycle.
The following example shows both the repackaged jar as well as the original jar in the target
directory:
$ mvn package $ ls target/*.jar target/myproject-1.0.0.jar target/myproject-1.0.0.jar.original
If you do not include the <execution/>
configuration, as shown in the prior example, you can run the plugin on its own (but only if the package goal is used as well), as shown in the following example:
$ mvn package spring-boot:repackage $ ls target/*.jar target/myproject-1.0.0.jar target/myproject-1.0.0.jar.original
If you use a milestone or snapshot release, you also need to add the appropriate pluginRepository
elements, as shown in the following listing:
<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>
8.1.2. Packaging Executable Jar and War Files
Once spring-boot-maven-plugin
has been included in your pom.xml
, it automatically tries to rewrite archives to make them executable by using the spring-boot:repackage
goal.
You should configure your project to build a jar or war (as appropriate) by using the usual packaging
element, as shown in the following example:
<?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">
<!-- ... -->
<packaging>jar</packaging>
<!-- ... -->
</project>
Your existing archive is enhanced by Spring Boot during the package
phase.
The main class that you want to launch can be specified either by using a configuration option, as shown below, or by adding a Main-Class
attribute to the manifest.
If you do not specify a main class, the plugin searches for a class with a public static void main(String[] args)
method.
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<mainClass>com.example.app.Main</mainClass>
</configuration>
</plugin>
To build and run a project artifact, you can type the following:
$ mvn package $ java -jar target/mymodule-0.0.1-SNAPSHOT.jar
To build a war file that is both executable and deployable into an external container, you need to mark the embedded container dependencies as “provided”, as shown in the following example:
<?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">
<!-- ... -->
<packaging>war</packaging>
<!-- ... -->
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
<scope>provided</scope>
</dependency>
<!-- ... -->
</dependencies>
</project>
See the “Create a Deployable War File” section for more details on how to create a deployable war file. |
Advanced configuration options and examples are available in the plugin info page.
8.2. 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 6.x (5.6 is also supported but this support is deprecated and will be removed in a future release).
Please refer to the plugin’s documentation to learn more:
8.3. 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 <folder containing spring-boot-antlib-2.3.0.M2.jar>
The “Using Spring Boot” section includes a more complete example of using Apache Ant with spring-boot-antlib .
|
8.3.1. Spring Boot Ant Tasks
Once the spring-boot-antlib
namespace has been declared, the following additional tasks are available:
spring-boot:exejar
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>
8.3.2. spring-boot:findmainclass
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" />
8.4. 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.
8.4.1. 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.
8.4.2. 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
.
8.4.3. 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.
8.4.4. Example Repackage Implementation
The following example shows a typical repackage implementation:
Repackager repackager = new Repackager(sourceJarFile);
repackager.setBackupSource(false);
repackager.repackage(new Libraries() {
@Override
public void doWithLibraries(LibraryCallback callback) throws IOException {
// Build system specific implementation, callback for each dependency
// callback.library(new Library(nestedFile, LibraryScope.COMPILE));
}
});
8.5. 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, you can check out the “how-to” guides.
9. “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 out 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.
9.1. Spring Boot Application
This section includes topics relating directly to Spring Boot applications.
9.1.1. 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 simply implement BeanFactoryAware or EnvironmentAware respectively.
|
9.1.2. 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
.
9.1.3. 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, per application, by setting the
context.initializer.classes
orcontext.listener.classes
properties. -
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 EnvironmentPostProcessorExample 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) {
if (!path.exists()) {
throw new IllegalArgumentException("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);
}
}
}
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.
|
9.1.4. 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.
9.1.5. 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 (e.g. 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.
9.2. Properties and Configuration
This section includes topics about setting and reading properties and configuration settings and their interaction with Spring Boot applications.
9.2.1. 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:
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 ${placeholder} ) in your configuration.
If that property is not set to false , these may be expanded by the build.
|
Automatic Property Expansion Using Gradle
You can automatically expand properties from the Gradle project by configuring the Java plugin’s processResources
task to do so, as shown in the following example:
processResources {
expand(project.properties)
}
You can then refer to your Gradle project’s properties by using placeholders, as shown in the following example:
app.name=${name}
app.description=${description}
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: \${..} .
|
9.2.2. Externalize the Configuration of SpringApplication
A SpringApplication
has bean properties (mainly 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
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 the values specified with the Java API, with the notable exception of the sources used to create the ApplicationContext
.
Consider the following application:
new SpringApplicationBuilder()
.bannerMode(Banner.Mode.OFF)
.sources(demo.MyApp.class)
.run(args);
Now consider the following configuration:
spring.main.sources=com.acme.Config,com.acme.ExtraConfig
spring.main.banner-mode=console
The actual application now shows the banner (as overridden by configuration) and uses three sources for the ApplicationContext
(in the following order): demo.MyApp
, com.acme.Config
, and com.acme.ExtraConfig
.
9.2.3. 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 ‘.yml’ extension are also added to the list.
Spring Boot logs the configuration files that are loaded at the DEBUG
level and the candidates it has not found at TRACE
level.
See ConfigFileApplicationListener
for more detail.
9.2.4. 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}
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.
|
9.2.5. 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:
driverClassName: com.mysql.jdbc.Driver
url: jdbc:mysql://localhost/test
server:
port: 9000
Create a file called application.yml
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 “Using YAML Instead of Properties” in the ‘Spring Boot features’ section for more information about YAML.
9.2.6. 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
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.
9.2.7. Change Configuration Depending on the Environment
A YAML file is actually a sequence of documents separated by ---
lines, and each document is parsed separately to a flattened map.
If a YAML document contains a spring.profiles
key, then the profiles value (a comma-separated list of profiles) is fed into the Spring Environment.acceptsProfiles()
method.
If any of those profiles is active, that document is included in the final merge (otherwise, it is not), as shown in the following example:
server:
port: 9000
---
spring:
profiles: development
server:
port: 9001
---
spring:
profiles: 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 YAML documents are merged in the order in which they are encountered. Later values override earlier values. |
To do the same thing with properties files, you can use application-${profile}.properties
to specify profile-specific values.
9.2.8. Discover Built-in Options for External Properties
Spring Boot binds external properties from application.properties
(or .yml
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".
9.3. 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.
9.3.1. 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 exclude the default dependencies in addition to including the one you need. Spring Boot provides separate starters for HTTP servers to help make this process as easy as possible.
The following Maven example shows how to exclude Tomcat and include Jetty for Spring MVC:
<properties>
<servlet-api.version>3.1.0</servlet-api.version>
</properties>
<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 version of the Servlet API has been overridden as, unlike Tomcat 9 and Undertow 2.0, Jetty 9.4 does not support Servlet 4.0. |
The following Gradle example shows how to exclude Netty and include Undertow for Spring WebFlux:
dependencies {
implementation('org.springframework.boot:spring-boot-starter-webflux') {
exclude group: 'org.springframework.boot', module: 'spring-boot-starter-reactor-netty'
}
// Use Undertow instead
implementation 'org.springframework.boot:spring-boot-starter-undertow'
// ...
}
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.
|
9.3.2. 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
9.3.3. 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.
9.3.4. Use a Random Unassigned HTTP Port
To scan for a free port (using OS natives to prevent clashes) use server.port=0
.
9.3.5. Discover the HTTP Port at Runtime
You can access the port the server is running on from log output or from the ServletWebServerApplicationContext
through its WebServer
.
The best way to get that and be sure that it has been initialized is to add a @Bean
of type ApplicationListener<ServletWebServerInitializedEvent>
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)
public class MyWebIntegrationTests {
@Autowired
ServletWebServerApplicationContext server;
@LocalServerPort
int port;
// ...
}
|
9.3.6. Enable HTTP Response Compression
HTTP response compression is supported by Jetty, Tomcat, and Undertow.
It can be enabled in application.properties
, as follows:
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.
9.3.7. Configure SSL
SSL can be configured declaratively by setting the various server.ssl.*
properties, typically in application.properties
or application.yml
.
The following example shows setting SSL properties in application.properties
:
server.port=8443
server.ssl.key-store=classpath:keystore.jks
server.ssl.key-store-password=secret
server.ssl.key-password=another-secret
See Ssl
for details of all of the supported properties.
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.
9.3.8. Configure HTTP/2
You can enable HTTP/2 support in your Spring Boot application with the server.http2.enabled
configuration property.
This support depends on the chosen web server and the application environment, since that protocol is not supported out-of-the-box by JDK8.
Spring Boot does not support |
HTTP/2 with Undertow
As of Undertow 1.4.0+, HTTP/2 is supported without any additional requirement on JDK8.
HTTP/2 with Jetty
As of Jetty 9.4.8, HTTP/2 is also supported with the Conscrypt library.
To enable that support, your application needs to have two additional dependencies: org.eclipse.jetty:jetty-alpn-conscrypt-server
and org.eclipse.jetty.http2:http2-server
.
HTTP/2 with Tomcat
Spring Boot ships by default with Tomcat 9.0.x which supports HTTP/2 out of the box when using JDK 9 or later.
Alternatively, HTTP/2 can be used on JDK 8 if the libtcnative
library and its dependencies are installed on the host operating system.
The library folder 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.
Starting Tomcat 9.0.x on JDK 8 without that native support logs the following error:
ERROR 8787 --- [ main] o.a.coyote.http11.Http11NioProtocol : The upgrade handler [org.apache.coyote.http2.Http2Protocol] for [h2] only supports upgrade via ALPN but has been configured for the ["https-jsse-nio-8443"] connector that does not support ALPN.
This error is not fatal, and the application still starts with HTTP/1.1 SSL support.
HTTP/2 with Reactor Netty
The spring-boot-webflux-starter
is using by default Reactor Netty as a server.
Reactor Netty can be configured for HTTP/2 using the JDK support with JDK 9 or later.
For JDK 8 environments, or for optimal runtime performance, this server also supports HTTP/2 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).
9.3.9. 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.yml
, or environment, etc. 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 doesn’t 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
}
}
In addition Spring Boot provides:
Server | Servlet stack | Reactive stack |
---|---|---|
Tomcat |
|
|
Jetty |
|
|
Undertow |
|
|
Reactor |
N/A |
|
Once you’ve got access to a WebServerFactory
, you can often add customizers to it to configure specific parts, like connectors, server resources, or the server itself - all using server-specific APIs.
As a last resort, you can also declare your own WebServerFactory
component, which will override the one provided by Spring Boot.
In this case, you can’t rely on configuration properties in the server
namespace anymore.
9.3.10. Add a Servlet, Filter, or Listener to an Application
In a servlet stack application, i.e. 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:
@Bean
public FilterRegistrationBean registration(MyFilter filter) {
FilterRegistrationBean registration = new FilterRegistrationBean(filter);
registration.setEnabled(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.
9.3.11. 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 ms)
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 ms)
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
By default, logs are redirected to System.err
.
For more details, see the Jetty documentation.
9.3.12. 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.
You can register it as a Servlet Filter in your application by setting server.forward-headers-strategy
is set to FRAMEWORK
.
If your application runs in Cloud Foundry or Heroku, 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
Tomcat is also configured with a default regular expression that matches internal proxies that are to be trusted.
By default, IP addresses in 10/8
, 192.168/16
, 169.254/16
and 127/8
are trusted.
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}
The double backslashes are required only when you use a properties file for configuration.
If you use YAML, single backslashes are sufficient, and a value equivalent to that shown in the preceding example would be 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 in a TomcatServletWebServerFactory
bean.
9.3.13. 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:
@Bean
public ServletWebServerFactory servletContainer() {
TomcatServletWebServerFactory tomcat = new TomcatServletWebServerFactory();
tomcat.addAdditionalTomcatConnectors(createSslConnector());
return tomcat;
}
private Connector createSslConnector() {
Connector connector = new Connector("org.apache.coyote.http11.Http11NioProtocol");
Http11NioProtocol protocol = (Http11NioProtocol) connector.getProtocolHandler();
try {
File keystore = new ClassPathResource("keystore").getFile();
File truststore = new ClassPathResource("keystore").getFile();
connector.setScheme("https");
connector.setSecure(true);
connector.setPort(8443);
protocol.setSSLEnabled(true);
protocol.setKeystoreFile(keystore.getAbsolutePath());
protocol.setKeystorePass("changeit");
protocol.setTruststoreFile(truststore.getAbsolutePath());
protocol.setTruststorePass("changeit");
protocol.setKeyAlias("apitester");
return connector;
}
catch (IOException ex) {
throw new IllegalStateException("can't access keystore: [" + keystore
+ "] or truststore: [" + truststore + "]", ex);
}
}
9.3.14. Use Tomcat’s LegacyCookieProcessor
By default, the embedded Tomcat used by Spring Boot does not support "Version 0" of the Cookie format, so you may see the following error:
java.lang.IllegalArgumentException: An invalid character [32] was present in the Cookie value
If at all possible, you should consider updating your code to only store values compliant with later Cookie specifications.
If, however, you cannot change the way that cookies are written, you can instead configure Tomcat to use a LegacyCookieProcessor
.
To switch to the LegacyCookieProcessor
, use an WebServerFactoryCustomizer
bean that adds a TomcatContextCustomizer
, as shown in the following example:
@Bean
public WebServerFactoryCustomizer<TomcatServletWebServerFactory> cookieProcessorCustomizer() {
return (factory) -> factory
.addContextCustomizers((context) -> context.setCookieProcessor(new LegacyCookieProcessor()));
}
9.3.15. 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 to expose metrics via Micrometer, you must use the server.tomcat.mbeanregistry.enabled
property to do so, as shown in the following example:
server.tomcat.mbeanregistry.enabled=true
9.3.16. Enable Multiple Listeners with Undertow
Add an UndertowBuilderCustomizer
to the UndertowServletWebServerFactory
and add a listener to the Builder
, as shown in the following example:
@Bean
public UndertowServletWebServerFactory servletWebServerFactory() {
UndertowServletWebServerFactory factory = new UndertowServletWebServerFactory();
factory.addBuilderCustomizers(new UndertowBuilderCustomizer() {
@Override
public void customize(Builder builder) {
builder.addHttpListener(8080, "0.0.0.0");
}
});
return factory;
}
9.3.17. 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:
@Bean
public ServerEndpointExporter serverEndpointExporter() {
return new 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.
9.4. 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.
9.4.1. 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();
}
}
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.
9.4.2. 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;
// .. getters and setters
}
JAXB is only available out of the box with Java 8. If you’re using a more recent Java generation, add the following dependency to your project:
<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).
|
9.4.3. 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
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 simple on/off features that can be used to configure various aspects of its processing.
These features are described in six enums (in Jackson) that map onto properties in the environment:
Enum | Property | Values |
---|---|---|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
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.
9.4.4. 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.
9.4.5. Handling Multipart File Uploads
Spring Boot embraces the Servlet 3 javax.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. |
9.4.6. 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=/acme
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
.
9.4.7. 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.
9.4.8. 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 ‘master’ 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:
9.5. 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.
@Test
@WithMockUser(roles="ADMIN")
public void requestProtectedUrlWithUser() throws Exception {
mvc
.perform(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, refer to Spring Security’s reference documentation).
9.6. Jersey
9.6.1. 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 JerseyConfig extends ResourceConfig {
public JerseyConfig() {
register(Endpoint.class);
setProperties(Collections.singletonMap("jersey.config.server.response.setStatusOverSendError", true));
}
}
9.6.2. 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);
}
}
9.7. HTTP Clients
Spring Boot offers a number of starters that work with HTTP clients. This section answers questions related to using them.
9.7.1. 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.
The following example configures HttpComponentsClientRequestFactory
with an HttpClient
that uses a proxy for all hosts except 192.168.0.5
:
static class ProxyCustomizer implements RestTemplateCustomizer {
@Override
public void customize(RestTemplate restTemplate) {
HttpHost proxy = new HttpHost("proxy.example.com");
HttpClient httpClient = HttpClientBuilder.create().setRoutePlanner(new DefaultProxyRoutePlanner(proxy) {
@Override
public HttpHost determineProxy(HttpHost target, HttpRequest request, HttpContext context)
throws HttpException {
if (target.getHostName().equals("192.168.0.5")) {
return null;
}
return super.determineProxy(target, request, context);
}
}).build();
restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory(httpClient));
}
}
9.7.2. 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
:
@Bean
ClientHttpConnector clientHttpConnector(ReactorResourceFactory resourceFactory) {
TcpClient tcpClient = TcpClient.create(resourceFactory.getConnectionProvider())
.runOn(resourceFactory.getLoopResources()).option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 60000)
.doOnConnected((connection) -> connection.addHandlerLast(new ReadTimeoutHandler(60)));
return new ReactorClientHttpConnector(HttpClient.from(tcpClient));
}
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.
|
9.8. 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 simplest 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
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.
9.8.1. Configure Logback for Logging
If you need to apply customizations to logback beyond those that can be achieved with application.properties
, you’ll 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 be included
from 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. -
${ROLLING_FILE_NAME_PATTERN}
: Whetherlogging.pattern.rolling-file-name
was set in Boot’s external configuration.
Spring Boot also provides some nice ANSI color terminal output on a console (but not in a log file) by using a custom Logback converter.
See the CONSOLE_LOG_PATTERN
in the defaults.xml
configuration for an example.
If Groovy is on the classpath, you should be able to configure Logback with logback.groovy
as well.
If present, this setting is given preference.
Spring extensions are not supported with Groovy configuration.
Any logback-spring.groovy files will not be detected.
|
Configure Logback for File-only Output
If you want to disable console logging and write output only to a file, you need a custom logback-spring.xml
that imports file-appender.xml
but not console-appender.xml
, as shown in the following example:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<include resource="org/springframework/boot/logging/logback/defaults.xml" />
<property name="LOG_FILE" value="${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
, as shown in the following example:
logging.file.name=myapplication.log
9.8.2. 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 simplest path is probably through the starters, even though it requires some jiggling with excludes. 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>
And the following example shows one way to set up the starters in Gradle:
dependencies {
implementation 'org.springframework.boot:spring-boot-starter-web'
implementation 'org.springframework.boot:spring-boot-starter-log4j2'
}
configurations {
all {
exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
}
}
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).
|
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 .
|
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 |
|
|
JSON |
|
|
9.9. Data Access
Spring Boot includes a number of starters for working with data sources. This section answers questions related to doing so.
9.9.1. 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:
@Bean
@ConfigurationProperties(prefix="app.datasource")
public DataSource dataSource() {
return new FancyDataSource();
}
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
Assuming that your FancyDataSource
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.
The regular database initialization also happens (so the relevant sub-set of spring.datasource.*
can still be used with your custom configuration).
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’s 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
:
@Bean
@ConfigurationProperties("app.datasource")
public 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
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.maximum-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
:
@Bean
@ConfigurationProperties("app.datasource")
public HikariDataSource dataSource() {
return DataSourceBuilder.create().type(HikariDataSource.class).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:
@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();
}
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
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.
9.9.2. 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:
@Bean
@Primary
@ConfigurationProperties("app.datasource.first")
public DataSourceProperties firstDataSourceProperties() {
return new DataSourceProperties();
}
@Bean
@Primary
@ConfigurationProperties("app.datasource.first.configuration")
public HikariDataSource firstDataSource() {
return firstDataSourceProperties().initializeDataSourceBuilder().type(HikariDataSource.class).build();
}
@Bean
@ConfigurationProperties("app.datasource.second")
public BasicDataSource secondDataSource() {
return DataSourceBuilder.create().type(BasicDataSource.class).build();
}
firstDataSourceProperties has to be flagged as @Primary so that the database initializer feature uses your copy (if you use the initializer).
|
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
You can apply the same concept to the secondary DataSource
as well, as shown in the following example:
@Bean
@Primary
@ConfigurationProperties("app.datasource.first")
public DataSourceProperties firstDataSourceProperties() {
return new DataSourceProperties();
}
@Bean
@Primary
@ConfigurationProperties("app.datasource.first.configuration")
public HikariDataSource firstDataSource() {
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() {
return secondDataSourceProperties().initializeDataSourceBuilder().type(BasicDataSource.class).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.
9.9.3. 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 @Repositories
are included in the same package (or a sub-package) of your @EnableAutoConfiguration
class.
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, etc.
To get started, create some repository interfaces to handle your @Entity
objects.
Spring Boot tries to guess the location of your @Repository
definitions, based on the @EnableAutoConfiguration
it finds.
To get more control, use the @EnableJpaRepositories
annotation (from Spring Data JPA).
For more about Spring Data, see the Spring Data project page.
9.9.4. Separate @Entity Definitions from Spring Configuration
Spring Boot tries to guess the location of your @Entity
definitions, based on the @EnableAutoConfiguration
it finds.
To get more control, you can use the @EntityScan
annotation, as shown in the following example:
@Configuration(proxyBeanMethods = false)
@EnableAutoConfiguration
@EntityScan(basePackageClasses=City.class)
public class Application {
//...
}
9.9.5. 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
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.
|
9.9.6. 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 SpringPhysicalNamingStrategy
.
This implementation provides the same table structure as Hibernate 4: all dots are replaced by underscores and camel casing is replaced by underscores as well.
By default, all table names are generated in lower case, but it is possible to override that flag if your schema requires it.
For example, a TelephoneNumber
entity is mapped to the telephone_number
table.
If you prefer to use Hibernate 5’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:
@Bean
public PhysicalNamingStrategy physicalNamingStrategy() {
return new PhysicalNamingStrategyStandardImpl();
}
See HibernateJpaAutoConfiguration
and JpaBaseConfiguration
for more details.
9.9.7. 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.
If you’re using JCache, this is pretty easy.
First, make sure that org.hibernate:hibernate-jcache
is available on the classpath.
Then, add a HibernatePropertiesCustomizer
bean as shown in the following example:
@Configuration(proxyBeanMethods = false)
public class HibernateSecondLevelCacheExample {
@Bean
public HibernatePropertiesCustomizer hibernateSecondLevelCacheCustomizer(JCacheCacheManager cacheManager) {
return (properties) -> properties.put(ConfigSettings.CACHE_MANAGER, cacheManager.getCacheManager());
}
}
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, refer to the Hibernate user guide.
9.9.8. 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 behaviour by registering a HibernatePropertiesCustomizer
that removes or changes the hibernate.resource.beans.container
property.
9.9.9. 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.
9.9.10. Use Two EntityManagers
Even if the default EntityManagerFactory
works fine, you need to define a new one.
Otherwise, the presence of the second bean of that type switches off the default.
To make it easy to do, you can use the convenient EntityManagerBuilder
provided by Spring Boot.
Alternatively, you can just the LocalContainerEntityManagerFactoryBean
directly from Spring ORM, as shown in the following example:
// add two data sources configured as above
@Bean
public LocalContainerEntityManagerFactoryBean customerEntityManagerFactory(
EntityManagerFactoryBuilder builder) {
return builder
.dataSource(customerDataSource())
.packages(Customer.class)
.persistenceUnit("customers")
.build();
}
@Bean
public LocalContainerEntityManagerFactoryBean orderEntityManagerFactory(
EntityManagerFactoryBuilder builder) {
return builder
.dataSource(orderDataSource())
.packages(Order.class)
.persistenceUnit("orders")
.build();
}
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.
On the other hand, properties that get applied to the auto-configured EntityManagerFactoryBuilder , which are specified via spring.jpa.properties , will automatically be applied, provided you use the auto-configured EntityManagerFactoryBuilder to build the LocalContainerEntityManagerFactoryBean bean.
|
The configuration above almost works on its own.
To complete the picture, you need to configure TransactionManagers
for the two EntityManagers
as well.
If you mark one of them as @Primary
, it could be picked up by the default JpaTransactionManager
in Spring Boot.
The other would have to be explicitly injected into a new instance.
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 example:
@Configuration(proxyBeanMethods = false)
@EnableJpaRepositories(basePackageClasses = Customer.class,
entityManagerFactoryRef = "customerEntityManagerFactory")
public class CustomerConfiguration {
...
}
@Configuration(proxyBeanMethods = false)
@EnableJpaRepositories(basePackageClasses = Order.class,
entityManagerFactoryRef = "orderEntityManagerFactory")
public class OrderConfiguration {
...
}
9.9.11. 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.
9.9.12. 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, Solr, and others). To work with them, change the names of the annotations and flags accordingly.
9.9.13. 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.
9.9.14. 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.
|
9.9.15. 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
static class ElasticsearchEntityManagerFactoryDependsOnPostProcessor
extends EntityManagerFactoryDependsOnPostProcessor {
ElasticsearchEntityManagerFactoryDependsOnPostProcessor() {
super("elasticsearchClient");
}
}
9.9.16. Configure jOOQ with Two DataSources
If you need to use jOOQ with multiple data sources, you should create your own DSLContext
for each one.
Refer to 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 .
|
9.10. 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.
9.10.1. 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.
9.10.2. 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.
hsqldb
, h2
, and derby
are embedded, 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).
9.10.3. Initialize a Database
Spring Boot can automatically create the schema (DDL scripts) of your DataSource
and initialize it (DML scripts).
It loads SQL from the standard root classpath locations: schema.sql
and data.sql
, respectively.
In addition, Spring Boot processes the schema-${platform}.sql
and data-${platform}.sql
files (if present), where platform
is the value of spring.datasource.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).
Spring Boot automatically creates the schema of an embedded spring.datasource.initialization-mode=always |
By default, Spring Boot enables the fail-fast feature of the Spring JDBC initializer.
This means that, if the scripts cause exceptions, the application fails to start.
You can tune that behavior by setting spring.datasource.continue-on-error
.
In a JPA-based app, you can choose to let Hibernate create the schema or use schema.sql , but you cannot do both.
Make sure to disable spring.jpa.hibernate.ddl-auto if you use schema.sql .
|
9.10.4. 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.initialize-schema=always
You can also switch off the initialization explicitly by setting spring.batch.initialize-schema=never
.
9.10.5. 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 folder 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
You can also add a special {vendor}
placeholder to use vendor-specific scripts.
Assume the following:
spring.flyway.locations=classpath:db/migration/{vendor}
Rather than using db/migration
, the preceding configuration sets the folder 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
folder.
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 be 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
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.
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.[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 be 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.
9.11. Messaging
Spring Boot offers a number of starters that include messaging. This section answers questions that arise from using messaging with Spring Boot.
9.11.1. 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:
@Bean
public DefaultJmsListenerContainerFactory jmsListenerContainerFactory(
ConnectionFactory connectionFactory,
DefaultJmsListenerContainerFactoryConfigurer configurer) {
DefaultJmsListenerContainerFactory listenerFactory =
new 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.
9.12. Batch Applications
A number of questions often arise when people use Spring Batch from within a Spring Boot application. This section addresses those questions.
9.12.1. 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, implement BatchConfigurer
.
See The Javadoc of @EnableBatchProcessing
for more details.
For more info about Spring Batch, see the Spring Batch project page.
9.12.2. Running Spring Batch Jobs on Startup
Spring Batch auto-configuration is enabled by adding @EnableBatchProcessing
to one of your @Configuration
classes.
By default, it executes all Jobs
in the application context on startup (see JobLauncherApplicationRunner
for details).
You can narrow down to a specific job or jobs by specifying spring.batch.job.names
(which takes a comma-separated list of job name patterns).
See BatchAutoConfiguration and @EnableBatchProcessing for more details.
9.12.3. 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 (i.e. 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
.
9.12.4. 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.
9.13. Actuator
Spring Boot includes the Spring Boot Actuator. This section answers questions that often arise from its use.
9.13.1. 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.
9.13.2. 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 a simple 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.
9.13.3. Sanitize sensible values
Information returned by the env
and configprops
endpoints can be somewhat sensitive so keys matching a certain pattern are sanitized by default (i.e. their values are replaced by ******
).
Spring Boot uses sensible defaults for such keys: for instance, any key ending with the word "password", "secret", "key" or "token" is sanitized.
It is also possible to use a regular expression instead, such as *credentials.*
to sanitize any key that holds the word credentials
as part of the key.
The patterns to use can be customized using the management.endpoint.env.keys-to-sanitize
and management.endpoint.configprops.keys-to-sanitize
respectively.
9.14. 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.
9.14.1. Switch off the Spring Boot Security Configuration
If you define a @Configuration
with a WebSecurityConfigurerAdapter
in your application, it switches off the default webapp security settings in Spring Boot.
9.14.2. 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.
9.14.3. 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
(The presence of either of those properties switches on the valve.
Alternatively, you can add the RemoteIpValve
by adding a TomcatServletWebServerFactory
bean.)
To configure Spring Security to require a secure channel for all (or some) requests, consider adding your own WebSecurityConfigurerAdapter
that adds the following HttpSecurity
configuration:
@Configuration(proxyBeanMethods = false)
public class SslWebSecurityConfigurerAdapter extends WebSecurityConfigurerAdapter {
@Override
protected void configure(HttpSecurity http) throws Exception {
// Customize the application security
http.requiresChannel().anyRequest().requiresSecure();
}
}
9.15. Hot Swapping
Spring Boot supports hot swapping. This section answers questions about how it works.
9.15.1. 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.
9.15.2. 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.
9.15.3. 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.
9.16. Build
Spring Boot includes build plugins for Maven and Gradle. This section answers common questions about these plugins.
9.16.1. 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>2.3.0.M2</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. |
9.16.2. 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 to your POM:
<build>
<plugins>
<plugin>
<groupId>pl.project13.maven</groupId>
<artifactId>git-commit-id-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 "1.5.1"
}
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.
|
9.16.3. Customize Dependency Versions
If you use a Maven build that inherits directly or indirectly from spring-boot-dependencies
(for instance, spring-boot-starter-parent
) but you want to override a specific third-party dependency, you can add appropriate <properties>
elements.
Browse the Version properties
for a complete list of version properties.
For example, to pick a different slf4j
version, you would add the following property:
<properties>
<slf4j.version>1.7.5<slf4j.version>
</properties>
Doing so only works if your Maven project inherits (directly or indirectly) from spring-boot-dependencies .
If you have added spring-boot-dependencies in your own dependencyManagement section with <scope>import</scope> , you have to redefine the artifact yourself instead of overriding the property.
|
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 in Gradle, see this section of the Gradle plugin’s documentation.
9.16.4. 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>2.3.0.M2</version>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
See the plugin documentation for full usage details.
9.16.5. 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>
9.16.6. 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>
9.16.7. 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.yml
configuration file might by 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.yml</exclude>
</excludes>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
9.16.8. 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.
9.16.9. 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-${spring-boot.version}.jar" />
<manifest>
<attribute name="Main-Class" value="org.springframework.boot.loader.JarLauncher" />
<attribute name="Start-Class" value="${start-class}" />
</manifest>
</jar>
</target>
9.17. Traditional Deployment
Spring Boot supports traditional deployment as well as more modern forms of deployment. This section answers common questions about traditional deployment.
9.17.1. 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 Application extends SpringBootServletInitializer {
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(Application.class);
}
public static void main(String[] args) {
SpringApplication.run(Application.class, 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.
9.17.2. Convert an Existing Application to Spring Boot
For a non-web application, it should be easy to convert an existing Spring application to a Spring Boot application.
To do so, throw away 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 Application 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 (via @SpringBootApplication)
// we actually don't 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, simple 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(Application.class, 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
|
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
.
9.17.3. 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:
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
import org.springframework.web.WebApplicationInitializer;
@SpringBootApplication
public class MyApplication extends SpringBootServletInitializer implements 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>
9.17.4. 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 these dependencies to help make this process as easy as possible.
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'
// ...
}
10. Appendices
Appendix A: Common Application properties
Various properties can be specified inside your application.properties
file, inside your application.yml
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. |
10.A.1. Core properties
Key | Default Value | Description |
---|---|---|
|
|
Enable debug logs. |
|
Arbitrary properties to add to the info endpoint. |
|
|
Location of the logging configuration file. For instance, `classpath:logback.xml` for Logback. |
|
|
|
Conversion word used when logging exceptions. |
|
|
Whether to clean the archive log files on startup. Only supported with the default logback setup. |
|
|
Maximum number of days archive log files are kept. Only supported with the default logback setup. |
|
|
Maximum log file size. Only supported with the default logback setup. |
|
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`. |
|
|
|
Total size of log backups to be kept. Only supported with the default logback setup. |
|
Log groups to quickly change multiple loggers at the same time. For instance, `logging.group.db=org.hibernate,org.springframework.jdbc`. |
|
|
Log levels severity mapping. For instance, `logging.level.org.springframework=DEBUG`. |
|
|
|
Appender pattern for output to the console. 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. |
|
|
Pattern for rolled-over log file names. Supported only with the default Logback setup. |
|
|
Register a shutdown hook for the logging system when it is initialized. |
|
|
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. |
|
|
The bit depth to use for ANSI colors. Supported values are 4 (16 color) or 8 (256 color). |
|
Height of the banner image in chars (default based on image height). |
|
|
|
Whether images should be inverted for dark terminal themes. |
|
|
Banner image file location (jpg or png can also be used). |
|
|
Left hand image margin in chars. |
|
|
The pixel mode to use when rendering the image. |
|
|
Width of the banner image in chars. |
|
|
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. By default this is not set, in which case individual codec defaults apply. Most codecs are limited to 256K by default. |
|
|
Config file locations used in addition to the defaults. |
|
|
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. |
|
|
MBeanServer bean name. |
|
|
Whether unique runtime object names should be ensured. |
|
|
Whether bean definition overriding, by registering a definition with the same name as an existing definition, is allowed. |
|
|
Mode used to display the banner when the application runs. |
|
|
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 profile expressions that at least one should match for the document to be included. |
|
|
Comma-separated list of active profiles. Can be overridden by a command line switch. |
|
|
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. |
|
|
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. |
|
|
Whether the Reactor Debug Agent should be enabled when reactor-tools is present. |
|
|
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. |
|
|
|
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. |
|
|
|
Prefix to use for the names of newly created threads. |
|
|
Enable trace logs. |
10.A.2. Cache properties
Key | Default Value | Description |
---|---|---|
|
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 EhCache. |
|
|
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. |
|
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. |
10.A.3. Mail properties
Key | Default Value | Description |
---|---|---|
|
|
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. |
10.A.4. JSON properties
Key | Default Value | Description |
---|---|---|
|
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. |
|
|
Date format string or a fully-qualified date format class name. For instance, `yyyy-MM-dd HH:mm:ss`. |
|
|
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 PropertyNamingStrategy. Can also be a fully-qualified class name of a PropertyNamingStrategy subclass. |
|
|
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. |
10.A.5. Data properties
Key | Default Value | Description |
---|---|---|
|
Couchbase nodes (host or IP address) to bootstrap from. |
|
|
|
Name of the bucket to connect to. |
|
Password of the bucket. |
|
|
Port for the HTTP bootstrap. |
|
|
Port for the HTTPS bootstrap. |
|
|
|
Number of sockets per node against the key/value service. |
|
|
Maximum number of sockets per node. |
|
|
Minimum number of sockets per node. |
|
|
Maximum number of sockets per node. |
|
|
Minimum number of sockets per node. |
|
Whether to enable SSL support. Enabled automatically if a "keyStore" is provided unless specified otherwise. |
|
|
Path to the JVM key store that holds the certificates. |
|
|
Password used to access the key store. |
|
|
|
Bucket connections timeouts. |
|
|
Blocking operations performed on a specific key timeout. |
|
|
N1QL query operations timeout. |
|
|
Socket connect connections timeout. |
|
|
Regular and geospatial view operations timeout. |
|
Cluster password when using role based access. |
|
|
Cluster username when using role based access. |
|
|
|
Whether to enable the PersistenceExceptionTranslationPostProcessor. |
|
|
Compression supported by the Cassandra binary protocol. |
|
Socket option: connection time out. |
|
|
Queries consistency level. |
|
|
|
Cluster node addresses in the form 'host:port'. |
|
Keyspace name to use. |
|
|
Datacenter that is considered "local". Contact points should be from this datacenter. |
|
|
|
Queries default page size. |
|
Login password of the server. |
|
|
|
Heartbeat interval after which a message is sent on an idle connection to make sure it's still alive. If a duration suffix is not specified, seconds will be used. |
|
|
Idle timeout before an idle connection is removed. If a duration suffix is not specified, seconds will be used. |
|
|
Maximum number of requests that get queued if no connection is available. |
|
Socket option: read time out. |
|
|
|
Type of Cassandra repositories to enable. |
|
|
Schema action to take at startup. |
|
Queries serial consistency level. |
|
|
Name of the Cassandra session. |
|
|
|
Enable SSL support. |
|
Login user of the server. |
|
|
|
Automatically create views and indexes. Use the meta-data provided by "@ViewIndexed", "@N1qlPrimaryIndexed" and "@N1qlSecondaryIndexed". |
|
|
Consistency to apply by default on generated queries. |
|
|
Type of Couchbase repositories to enable. |
|
|
Name of the field that stores the type information for complex types when using "MappingCouchbaseConverter". |
|
Connection timeout. |
|
|
Comma-separated list of the Elasticsearch endpoints to connect to. |
|
|
Credentials password. |
|
|
Read and Write Socket timeout. |
|
|
|
Whether the client should use SSL to connect to the endpoints. |
|
Credentials username. |
|
|
|
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. |
|
Authentication database name. |
|
|
Whether to enable auto-index creation. |
|
|
Database name. |
|
|
Fully qualified name of the FieldNamingStrategy to use. |
|
|
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. |
|
|
|
Type of Mongo repositories to enable. |
|
|
Mongo database URI. Cannot be set with host, port and credentials. |
|
Login user of the mongo server. Cannot be set with URI. |
|
|
|
Representation to use when converting a UUID to a BSON binary value. |
|
|
Auto index mode. |
|
|
Whether to enable embedded mode if the embedded driver is available. |
|
|
Register OpenSessionInViewInterceptor that binds a Neo4j Session to the thread for the entire processing of the request. |
|
Login password of the server. |
|
|
|
Whether to enable Neo4j repositories. |
|
URI used by the driver. Auto-detected by default. |
|
|
|
Whether to use Neo4j native types wherever possible. |
|
Login user of the server. |
|
|
|
Whether to enable Redis repositories. |
|
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. |
|
|
|
Solr host. Ignored if "zk-host" is set. |
|
|
Whether to enable Solr repositories. |
|
ZooKeeper host address in the form HOST:PORT. |
|
|
|
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. |
|
|
Whether to stop if an error occurs while initializing the database. |
|
Data (DML) script resource references. |
|
|
Password of the database to execute DML scripts (if different). |
|
|
Username of the database to execute DML scripts (if different). |
|
|
Commons DBCP2 specific settings |
|
|
Fully qualified name of the JDBC driver. Auto-detected based on the URL by default. |
|
|
|
Whether to generate a random datasource name. |
|
Hikari specific settings |
|
|
|
Initialize the datasource with available DDL and DML scripts. |
|
JNDI location of the datasource. Class, url, username and password are ignored when set. |
|
|
Name of the datasource. Default to "testdb" when using an embedded database. |
|
|
Login password of the database. |
|
|
|
Platform to use in the DDL or DML scripts (such as schema-${platform}.sql or data-${platform}.sql). |
|
Schema (DDL) script resource references. |
|
|
Password of the database to execute DDL scripts (if different). |
|
|
Username of the database to execute DDL scripts (if different). |
|
|
|
Statement separator in SQL initialization scripts. |
|
SQL scripts encoding. |
|
|
Tomcat datasource specific settings |
|
|
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. |
|
Credentials password. |
|
|
|
Read timeout. |
|
|
Comma-separated list of the Elasticsearch instances to use. |
|
Credentials username. |
|
|
|
Whether to enable the console. |
|
|
Path at which the console is available. |
|
|
Whether to enable trace output. |
|
|
Whether to enable remote access. |
|
Login password. |
|
|
URL of the InfluxDB instance to which to connect. |
|
|
Login user. |
|
|
|
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 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. |
|
|
Whether to use Hibernate's newer IdentifierGenerator for AUTO, TABLE and SEQUENCE. This is actually a shortcut for the "hibernate.id.new_generator_mappings" property. When not specified will default to "true". |
|
|
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. |
|
|
Comma-separated list of features to enable. Uses the defaults of the configured version by default. |
|
Directory used for data storage. |
|
|
Maximum size of the oplog. |
|
|
Name of the replica set. |
|
|
|
Version of Mongo to use. |
|
Client name to be set on connections with CLIENT SETNAME. |
|
|
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. |
|
|
|
Database index used by the connection factory. |
|
|
Redis server host. |
|
|
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. |
|
|
|
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. |
|
Name of the Redis server. |
|
|
Comma-separated list of "host:port" pairs. |
|
|
|
Whether to enable SSL support. |
|
Connection timeout. |
|
|
Connection URL. Overrides host, port, and password. User is ignored. Example: redis://user:[email protected]:6379 |
10.A.6. Transaction properties
Key | Default Value | Description |
---|---|---|
|
|
Timeout, in seconds, for borrowing connections from the pool. |
|
|
Whether to ignore the transacted flag when creating session. |
|
|
Whether local transactions are desired. |
|
|
Time, in seconds, between runs of the pool's maintenance thread. |
|
|
Time, in seconds, after which connections are cleaned up from the pool. |
|
|
Time, in seconds, that a connection can be pooled for before being destroyed. 0 denotes no limit. |
|
|
Maximum size of the pool. |
|
|
Minimum size of the pool. |
|
|
Reap timeout, in seconds, for borrowed connections. 0 denotes no limit. |
|
|
Unique name used to identify the resource during recovery. |
|
Vendor-specific implementation of XAConnectionFactory. |
|
|
Vendor-specific XA properties. |
|
|
|
Timeout, in seconds, for borrowing connections from the pool. |
|
|
Whether to use concurrent connection validation. |
|
Default isolation level of connections provided by the pool. |
|
|
|
Timeout, in seconds, for establishing a database connection. |
|
|
Time, in seconds, between runs of the pool's maintenance thread. |
|
|
Time, in seconds, after which connections are cleaned up from the pool. |
|
|
Time, in seconds, that a connection can be pooled for before being destroyed. 0 denotes no limit. |
|
|
Maximum size of the pool. |
|
|
Minimum size of the pool. |
|
|
Reap timeout, in seconds, for borrowed connections. 0 denotes no limit. |
|
SQL query or statement used to validate a connection before returning it. |
|
|
|
Unique name used to identify the resource during recovery. |
|
Vendor-specific implementation of XAConnectionFactory. |
|
|
Vendor-specific XA properties. |
|
|
|
Specify whether sub-transactions are allowed. |
|
|
Interval between checkpoints, expressed as the number of log writes between two checkpoints. A checkpoint reduces the log file size at the expense of adding some overhead in the runtime. |
|
|
Default timeout for JTA transactions. |
|
How long should normal shutdown (no-force) wait for transactions to complete. |
|
|
|
Whether to enable disk logging. |
|
|
Whether a VM shutdown should trigger forced shutdown of the transaction core. |
|
Directory in which the log files should be stored. Defaults to the current working directory. |
|
|
|
Transactions log file base name. |
|
|
Maximum number of active transactions. |
|
|
Maximum timeout that can be allowed for transactions. |
|
|
Delay between two recovery scans. |
|
|
Delay after which recovery can cleanup pending ('orphaned') log entries. |
|
|
Number of retry attempts to commit the transaction before throwing an exception. |
|
|
Delay between retry attempts. |
|
|
Whether sub-transactions should be joined when possible. |
|
Transaction manager implementation that should be started. |
|
|
|
Whether to use different (and concurrent) threads for two-phase commit on the participating resources. |
|
The transaction manager's unique name. Defaults to the machine's IP address. If you plan to run more than one transaction manager against one database you must set this property to a unique value. |
|
|
|
Number of connections to create when growing the pool. |
|
|
Time, in seconds, to wait before trying to acquire a connection again after an invalid connection was acquired. |
|
|
Timeout, in seconds, for acquiring connections from the pool. |
|
|
Whether the transaction manager should allow mixing XA and non-XA transactions. |
|
|
Whether the transaction timeout should be set on the XAResource when it is enlisted. |
|
|
Whether resources should be enlisted and delisted automatically. |
|
|
Whether producers and consumers should be cached. |
|
Underlying implementation class name of the XA resource. |
|
|
|
Whether the provider can run many transactions on the same connection and supports transaction interleaving. |
|
|
Whether this resource is disabled, meaning it's temporarily forbidden to acquire a connection from its pool. |
|
Properties that should be set on the underlying implementation. |
|
|
||
|
|
Whether recovery failures should be ignored. |
|
|
Time, in seconds, after which connections are cleaned up from the pool. |
|
|
Maximum size of the pool. 0 denotes no limit. |
|
|
Minimum size of the pool. |
|
Password to use to connect to the JMS provider. |
|
|
|
Whether connections in the ACCESSIBLE state can be shared within the context of a transaction. |
|
|
Whether connections should be tested when acquired from the pool. |
|
|
Position that this resource should take during two-phase commit (always first is Integer.MIN_VALUE, always last is Integer.MAX_VALUE). |
|
|
Unique name used to identify the resource during recovery. |
|
|
Whether TMJOIN should be used when starting XAResources. |
|
User to use to connect to the JMS provider. |
|
|
|
Number of connections to create when growing the pool. |
|
|
Time, in seconds, to wait before trying to acquire a connection again after an invalid connection was acquired. |
|
|
Timeout, in seconds, for acquiring connections from the pool. |
|
|
Whether the transaction manager should allow mixing XA and non-XA transactions. |
|
|
Whether the transaction timeout should be set on the XAResource when it is enlisted. |
|
|
Whether resources should be enlisted and delisted automatically. |
|
Underlying implementation class name of the XA resource. |
|
|
Default cursor holdability for connections. |
|
|
|
Whether the database can run many transactions on the same connection and supports transaction interleaving. |
|
|
Whether this resource is disabled, meaning it's temporarily forbidden to acquire a connection from its pool. |
|
Properties that should be set on the underlying implementation. |
|
|
|
Whether Connection.isValid() is called when acquiring a connection from the pool. |
|
||
|
|
Whether recovery failures should be ignored. |
|
Default isolation level for connections. |
|
|
Default auto-commit mode for local transactions. |
|
|
Timeout, in seconds, for establishing a database connection. |
|
|
|
Time, in seconds, after which connections are cleaned up from the pool. |
|
|
Maximum size of the pool. 0 denotes no limit. |
|
|
Minimum size of the pool. |
|
|
Target size of the prepared statement cache. 0 disables the cache. |
|
|
Whether connections in the ACCESSIBLE state can be shared within the context of a transaction. |
|
SQL query or statement used to validate a connection before returning it. |
|
|
|
Position that this resource should take during two-phase commit (always first is Integer.MIN_VALUE, and always last is Integer.MAX_VALUE). |
|
|
Unique name used to identify the resource during recovery. |
|
|
Whether TMJOIN should be used when starting XAResources. |
|
|
Whether to allow multiple LRC resources to be enlisted into the same transaction. |
|
|
Whether to enable asynchronously execution of two phase commit. |
|
|
Interval in seconds at which to run the recovery process in the background. |
|
|
Whether to recover only the current node. Should be enabled if you run multiple instances of the transaction manager on the same JMS and JDBC resources. |
|
|
Whether to log the creation and commit call stacks of transactions executed without a single enlisted resource. |
|
|
Default transaction timeout, in seconds. |
|
|
Whether to enable JMX support. |
|
Set the fully qualified name of the exception analyzer implementation to use. |
|
|
|
Whether to enable filtering of logs so that only mandatory logs are written. |
|
|
Whether disk forces are batched. |
|
|
Whether logs are forced to disk. |
|
|
Maximum amount of seconds the TM waits for transactions to get done before aborting them at shutdown time. |
|
JNDI name of the TransactionSynchronizationRegistry. |
|
|
JNDI name of the UserTransaction. |
|
|
|
Name of the journal. Can be 'disk', 'null', or a class name. |
|
|
Name of the first fragment of the journal. |
|
|
Name of the second fragment of the journal. |
|
|
Maximum size in megabytes of the journal fragments. |
|
ResourceLoader configuration file name. |
|
|
ASCII ID that must uniquely identify this TM instance. Defaults to the machine's IP address. |
|
|
|
Skip corrupted transactions log entries. Use only at last resort when all you have to recover is a pair of corrupted files. |
|
|
Whether to log a warning for transactions executed without a single enlisted resource. |
|
|
Whether to enable JTA support. |
|
Transaction logs directory. |
|
|
Transaction manager unique identifier. |
|
|
Default transaction timeout. If a duration suffix is not specified, seconds will be used. |
|
|
Whether to roll back on commit failures. |
10.A.7. Data migration properties
Key | Default Value | Description |
---|---|---|
|
|
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 Pro or Flyway Enterprise. |
|
|
|
Whether to check that migration scripts location exists. |
|
|
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. |
|
Default schema name managed by Flyway (case-sensitive). |
|
|
|
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 Pro or Flyway Enterprise. |
|
|
|
Whether to group all pending migrations together in the same transaction when applying them. |
|
|
Whether to ignore future migrations when reading the schema history table. |
|
|
Whether to ignore ignored migrations when reading the schema history table. |
|
|
Whether to ignore missing migrations when reading the schema history table. |
|
|
Whether to ignore pending migrations when reading the schema history table. |
|
SQL statements to execute to initialize a connection immediately after obtaining it. |
|
|
Username recorded in the schema history table as having applied the migration. |
|
|
Licence key for Flyway Pro or Flyway Enterprise. |
|
|
|
Locations of migrations scripts. Can contain the special "{vendor}" placeholder to use vendor-specific locations. |
|
|
Whether to allow mixing transactional and non-transactional statements within the same migration. |
|
Whether to enable support for Oracle SQL*Plus commands. Requires Flyway Pro or Flyway Enterprise. |
|
|
Whether to issue a warning rather than an error when a not-yet-supported Oracle SQL*Plus statement is encountered. Requires Flyway Pro or Flyway Enterprise. |
|
|
|
Whether to allow migrations to be run out of order. |
|
Login password of the database to migrate. |
|
|
|
Prefix of placeholders in migration scripts. |
|
|
Perform placeholder replacement in migration scripts. |
|
|
Suffix of placeholders in migration scripts. |
|
Placeholders and their replacements to apply to sql migration scripts. |
|
|
|
File name prefix for repeatable SQL migrations. |
|
Scheme names managed by Flyway (case-sensitive). |
|
|
|
Whether to skip default callbacks. If true, only custom callbacks are used. |
|
|
Whether to skip default resolvers. If true, only custom resolvers are used. |
|
|
File name prefix for SQL migrations. |
|
|
File name separator for SQL migrations. |
|
|
File name suffix for SQL migrations. |
|
Whether to stream SQL migrations when executing them. Requires Flyway Pro or Flyway Enterprise. |
|
|
|
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. |
|
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. |
|
|
|
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 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. |
10.A.8. Integration properties
Key | Default Value | Description |
---|---|---|
|
URL of the ActiveMQ broker. Auto-generated by default. |
|
|
|
Time to wait before considering a close complete. |
|
|
Whether the default broker URL should be in memory. Ignored if an explicit broker has been specified. |
|
|
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. |
|
|
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 broker host. |
|
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. |
|
|
Artemis broker port. |
|
Login user of the broker. |
|
|
|
Database schema initialization mode. |
|
|
Execute all Spring Batch jobs in the context on startup. |
|
Comma-separated list of job names to execute on startup (for instance, `job1,job2`). By default, all Jobs found in the context are executed. |
|
|
|
Path to the SQL file to use to initialize the database schema. |
|
Table prefix for all the batch meta-data tables. |
|
|
The location of the configuration file to use to initialize Hazelcast. |
|
|
|
Database schema initialization mode. |
|
|
Path to the SQL file to use to initialize the database schema. |
|
|
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. |
|
|
Acknowledge mode of the container. By default, the listener is transacted with automatic acknowledgment. |
|
|
|
Start the container automatically on startup. |
|
Minimum number of concurrent consumers. |
|
|
Maximum number of concurrent consumers. |
|
|
|
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. |
|
|
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. |
|
|
Time-to-live of a message when sending. Enables QoS (Quality of Service) when set. |
|
|
ID to pass to the server when making requests. Used for server-side logging. |
|
|
|
Whether to fail fast if the broker is not available on startup. |
|
Additional admin-specific properties used to configure the client. |
|
|
Password of the private key in the key store file. |
|
|
Location of the key store file. |
|
|
Store password for the key store file. |
|
|
Type of the key store. |
|
|
SSL protocol to use. |
|
|
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. |
|
|
Password of the private key in the key store file. |
|
|
Location of the key store file. |
|
|
Store password for the key store file. |
|
|
Type of the key store. |
|
|
SSL protocol to use. |
|
|
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". |
|
|
Prefix for the listener's consumer client.id property. |
|
|
Number of threads to run in the listener containers. |
|
|
Time between publishing idle consumer events (no data received). |
|
|
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. |
|
|
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. |
|
|
Password of the private key in the key store file. |
|
|
Location of the key store file. |
|
|
Store password for the key store file. |
|
|
Type of the key store. |
|
|
SSL protocol to use. |
|
|
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. |
|
|
Password of the private key in the key store file. |
|
|
Location of the key store file. |
|
|
Store password for the key store file. |
|
|
Type of the key store. |
|
|
SSL protocol to use. |
|
|
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 or not 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. |
|
|
Maximum memory size to be used for buffering across all threads. |
|
|
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. |
|
|
Password of the private key in the key store file. |
|
|
Location of the key store file. |
|
|
Store password for the key store file. |
|
|
Type of the key store. |
|
|
SSL protocol to use. |
|
|
Location of the trust store file. |
|
|
Store password for the trust store file. |
|
|
Type of the trust store. |
|
|
Directory location for the state store. |
|
|
Default topic to which messages are sent. |
|
|
Comma-separated list of addresses to which the client should connect. |
|
|
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. |
|
|
Connection timeout. Set it to zero to wait forever. |
|
|
|
Whether to create an AmqpAdmin bean. |
|
|
RabbitMQ host. |
|
Acknowledge mode of container. |
|
|
|
Whether to start the container automatically on startup. |
|
Number of consumers per queue. |
|
|
Whether rejected deliveries are re-queued by default. |
|
|
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 rejected deliveries are re-queued by default. |
|
|
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. |
|
|
Listener container type. |
|
|
Login to authenticate against the broker. |
|
|
RabbitMQ port. |
|
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. |
|
|
|
Whether to enable SSL support. |
|
Path to the key store that holds the SSL certificate. |
|
|
Password used to access the key store. |
|
|
|
Key store type. |
|
Trust store that holds SSL certificates. |
|
|
Password used to access the trust store. |
|
|
|
Trust store type. |
|
|
Whether to enable server side certificate validation. |
|
|
Whether to enable hostname verification. |
|
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. |
10.A.9. Web properties
Key | Default Value | Description |
---|---|---|
|
|
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. |
|
|
Whether the path extension in the URL path should be used to determine the requested media type. If enabled a request "/users.pdf" will be interpreted as a request for "application/pdf" regardless of the 'Accept' header. |
|
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. |
|
|
Date format to use. For instance, `dd/MM/yyyy`. |
|
|
|
Whether to dispatch OPTIONS requests to the FrameworkServlet doService method. |
|
|
Whether to dispatch TRACE requests to the FrameworkServlet doService method. |
|
|
Whether to enable Spring's FormContentFilter. |
|
|
Whether to enable Spring's HiddenHttpMethodFilter. |
|
|
Whether the content of the "default" model should be ignored during redirect scenarios. |
|
Locale to use. By default, this locale is overridden by the "Accept-Language" header. |
|
|
|
Define how the locale should be resolved. |
|
|
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`. |
|
|
|
Whether suffix pattern matching should work only against extensions registered with "spring.mvc.contentnegotiation.media-types.*". This is generally recommended to reduce ambiguity and to avoid issues such as when a "." appears in the path for other reasons. |
|
|
Whether to use suffix pattern match (".*") when matching patterns to requests. If enabled a method mapped to "/users" also matches to "/users.*". |
|
|
Whether to publish a ServletRequestHandledEvent at the end of each request. |
|
|
Load on startup priority of the dispatcher servlet. |
|
|
Path of the dispatcher servlet. |
|
|
Path pattern used for static resources. |
|
|
Whether a "NoHandlerFoundException" should be thrown if no Handler was found to process a request. |
|
Spring MVC view prefix. |
|
|
Spring MVC view suffix. |
|
|
|
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.resources.cache.cachecontrol' properties. |
|
|
|
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 HTML5 application cache manifest rewriting. |
|
|
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/]. |
|
|
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. |
|
Date format to use. For instance, `dd/MM/yyyy`. |
|
|
|
Whether to enable Spring's HiddenHttpMethodFilter. |
|
|
Path pattern used for static resources. |
10.A.10. Templating properties
Key | Default Value | Description |
---|---|---|
|
|
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. File system access enables hot detection of template changes. |
|
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. |
|
White list of 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. |
|
White list of 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. |
|
|
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 to apply to template names. |
|
Name of the RequestContext attribute for all views. |
|
|
|
Suffix to apply to template names. |
|
White list of 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. |
10.A.11. Server properties
Key | Default Value | Description |
---|---|---|
|
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. |
|
|
Include the "exception" attribute. |
|
|
When to include a "stacktrace" 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. |
|
|
Number of acceptor threads to use. When the value is -1, the default, the number of acceptors is derived from the operating environment. |
|
|
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 size of the form content in any HTTP post request. |
|
|
Maximum number of threads. |
|
|
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 thread idle time. |
|
|
Maximum size of the HTTP message header. |
|
Connection timeout of the Netty channel. |
|
|
|
Server HTTP port. |
|
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. |
|
|
||
|
|
Whether to enable http encoding support. |
|
||
|
||
|
||
|
||
|
|
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. |
|
Comment for the session cookie. |
|
|
Domain for the session cookie. |
|
|
Whether to use "HttpOnly" cookies for session cookies. |
|
|
Maximum age of the session cookie. If a duration suffix is not specified, seconds will be used. |
|
|
Session cookie name. |
|
|
Path of the session cookie. |
|
|
Whether to always mark the session 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. |
|
|
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. |
|
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 it 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. |
|
|
|
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 amount of request body to swallow. |
|
|
Maximum amount of worker threads. |
|
|
Whether Tomcat's MBean Registry should be enabled. |
|
|
Minimum amount of worker threads. |
|
|
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. |
|
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`. |
|
|
|
Whether static resource caching is permitted for this web application. |
|
Time-to-live of the static resource cache. |
|
|
|
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 server should decode percent encoded slash characters. Enabling encoded slashes can have security implications due to different servers interpreting the slash differently. Only enable this if you have a legacy application that requires it. |
|
|
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 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. |
|
Number of I/O threads to create for the worker. The default is derived from the number of available processors. |
|
|
|
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. |
|
|
||
|
||
|
|
Charset used to decode URLs. |
|
Number of worker threads. The default is 8 times the number of I/O threads. |
10.A.12. Security properties
Key | Default Value | Description |
---|---|---|
|
|
Whether read-only operations should use an anonymous environment. |
|
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. |
|
|
LDAP URLs of the server. |
|
|
Login username of the server. |
|
|
|
Security filter chain dispatcher types. |
|
|
Security filter chain order. |
|
OAuth provider details. |
|
|
OAuth client registrations. |
|
|
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 Algorithm 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. |
|
|
|
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. |
|
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. |
|
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. |
|
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 store type. |
|
|
Session timeout. If a duration suffix is not specified, seconds will be used. |
10.A.13. RSocket properties
Key | Default Value | Description |
---|---|---|
|
Network address to which the server should bind. |
|
|
Path under which RSocket handles requests (only works with websocket transport). |
|
|
Server port. |
|
|
RSocket transport protocol. |
10.A.14. Actuator properties
Key | Default Value | Description |
---|---|---|
|
|
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. |
|
|
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. |
|
|
Keys that should be sanitized. Keys can be simple strings that the property ends with or regular expressions. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the env endpoint. |
|
|
Keys that should be sanitized. Keys can be simple strings that the property ends with or regular expressions. |
|
|
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. |
|
|
Roles used to determine whether or not 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. |
|
|
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 httptrace 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. |
|
Jolokia settings. Refer to the documentation of Jolokia for more details. |
|
|
|
Whether to enable the jolokia 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. |
|
|
Maximum time that a response can be cached. |
|
|
Whether to enable the prometheus endpoint. |
|
|
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 threaddump endpoint. |
|
Whether to enable or disable all endpoints by default. |
|
|
|
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 server.servlet.context-path or management.server.servlet.context-path if 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 origins to allow. '*' allows all origins. When not 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. |
|
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. |
|
|
|
Whether to enable Cassandra health check. |
|
|
Whether to enable Couchbase health check. |
|
|
Whether to enable database health check. |
|
|
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 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 Redis health check. |
|
|
Whether to enable Solr health check. |
|
|
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. |
|
Maximum value that meter IDs starting-with the specified name are expected to observe. The longest match wins. Values can be specified as a long 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 long or as a Duration value (for timer meters, defaulting to ms if no unit specified). |
|
|
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 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. |
|
|
Specific SLA 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 long 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. |
|
|
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. |
|
|
Tag that will be mapped to "@host" when shipping metrics to AppOptics. |
|
|
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 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. |
|
|
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. |
|
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. |
|
|
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 to ship metrics to. If you need to publish metrics to an internal proxy en-route to Datadog, you can define the location of the proxy with this. |
|
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. |
|
ID of the custom device that is exporting metrics to Dynatrace. |
|
|
|
Whether exporting of metrics to this backend is enabled. |
|
Group for exported metrics. Used to specify custom device group name in the Dynatrace UI. |
|
|
|
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. |
|
|
Technology type for exported metrics. Used to group metrics under a logical technology name in the Dynatrace UI. |
|
URI to ship metrics to. Should be used for SaaS, self managed instances or to en-route through an internal proxy. |
|
|
|
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, preceded by a '-'. |
|
|
Number of threads to use with the metrics publishing scheduler. |
|
Login password of the Elastic server. |
|
|
|
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. |
|
|
|
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. |
|
|
Ganglia protocol version. Must be either 3.1 or 3.0. |
|
|
Base time unit used to report rates. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
Time to live for metrics on Ganglia. Set the multi-cast 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. |
|
|
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 default naming convention, turn the specified tag keys into part of the metric prefix. |
|
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. |
|
|
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. |
|
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. |
|
|
Whether to create the Influx database if it does not exist before attempting to publish metrics to it. |
|
|
Number of measurements per request to use for this backend. If more measurements are found, then multiple requests will be made. |
|
|
Whether to enable GZIP compression of metrics batches published to Influx. |
|
|
Connection timeout for requests to this backend. |
|
|
Write consistency for each point. |
|
|
Tag that will be mapped to "host" when shipping metrics to Influx. |
|
|
Whether exporting of metrics to this backend is enabled. |
|
|
Number of threads to use with the metrics publishing scheduler. |
|
Login password of the Influx server. |
|
|
|
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. |
|
|
Retention policy to use (Influx writes to the DEFAULT retention policy if one is not specified). |
|
|
How many copies of the data are stored in the cluster. Must be 1 for a single node instance. |
|
|
Time range covered by a shard group. For instance 2w, check the influx documentation for more details on the duration format. |
|
|
|
Step size (i.e. reporting frequency) to use. |
|
|
URI of the Influx server. |
|
Login user of the Influx server. |
|
|
|
Metrics JMX domain name. |
|
|
Whether exporting of metrics to JMX 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. |
|
|
Number of threads to use with the metrics publishing scheduler. |
|
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. |
|
|
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. |
|
|
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. |
|
|
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 to ship metrics to. |
|
|
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 Prometheus is enabled. |
|
|
Base URL for the Pushgateway. |
|
|
Enable publishing via a Prometheus Pushgateway. |
|
Grouping key for the pushed metrics. |
|
|
Job identifier for this application instance. |
|
|
|
Frequency with which to push metrics. |
|
Operation that should be performed on shutdown. |
|
|
|
Step size (i.e. reporting frequency) to use. |
|
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. |
|
|
Number of threads to use with the metrics publishing scheduler. |
|
|
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, in the absence of any other exporter, exporting of metrics to an in-memory 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. |
|
|
Number of threads to use with the metrics publishing scheduler. |
|
Identifier of the Google Cloud project to monitor. |
|
|
|
Read timeout for requests to this backend. |
|
|
Monitored resource type. |
|
|
Step size (i.e. reporting frequency) to use. |
|
|
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. |
|
|
Whether to send unchanged meters to the StatsD server. |
|
API token used when publishing metrics directly to the Wavefront API host. |
|
|
|
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 white box instrumentation from those originating from other Wavefront integrations when viewed in the Wavefront UI. |
|
|
|
Number of threads to use with the metrics publishing scheduler. |
|
|
Read timeout for requests to this backend. |
|
Unique identifier for the app instance that is the source of metrics being published to Wavefront. Defaults to the local host name. |
|
|
|
Step size (i.e. reporting frequency) to use. |
|
|
URI to ship metrics to. |
|
Common tags that are applied to every meter. |
|
|
|
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. |
|
|
Whether to automatically time web client requests. |
|
Computed non-aggregable percentiles to publish. |
|
|
|
Whether percentile histograms should be published. |
|
|
Name of the metric for sent requests. |
|
|
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. |
|
|
Whether to automatically time web server requests. |
|
Computed non-aggregable percentiles to publish. |
|
|
|
Whether percentile histograms should be published. |
|
|
Whether the trailing slash should be ignored when recording metrics. |
|
|
Name of the metric for received requests. |
|
|
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 HTTP port (uses the same port as the application by default). Configure a different port to use management-specific SSL. |
|
|
Management endpoint context-path (for instance, `/management`). Requires a custom management.server.port. |
|
|
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. |
|
Trust store that holds SSL certificates. |
|
|
Password used to access the trust store. |
|
|
Provider for the trust store. |
|
|
Type of the trust store. |
|
|
|
Whether to enable HTTP request-response tracing. |
|
|
Items to be included in the trace. Defaults to request headers (excluding Authorization but including Cookie), response headers (including Set-Cookie), and time taken. |
10.A.15. Devtools properties
Key | Default Value | Description |
---|---|---|
|
|
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. |
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.yml
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.
10.B.1. Metadata Format
Configuration metadata files are located inside jars under META-INF/spring-configuration-metadata.json
.
They use a simple 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 application.properties
, as follows:
server.port=9090
server.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. |
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 app.acme.target
property was confusing and was renamed to app.acme.name
.
The following example shows how to handle that situation:
@ConfigurationProperties("app.acme")
public class AcmeProperties {
private String name;
public String getName() { ... }
public void setName(String name) { ... }
@DeprecatedConfigurationProperty(replacement = "app.acme.name")
@Deprecated
public String getTarget() {
return getName();
}
@Deprecated
public void setTarget(String target) {
setName(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.
10.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 sample.contexts
maps magic String
values to an integer, as shown in the following example:
@ConfigurationProperties("sample")
public class SampleProperties {
private Map<String,Integer> contexts;
// getters and setters
}
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": "sample.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": "javax.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"
}
]
}
]}
10.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.
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 4.5 and earlier, the dependency should be declared in the compileOnly
configuration, as shown in the following example:
dependencies {
compileOnly "org.springframework.boot:spring-boot-configuration-processor"
}
With Gradle 4.6 and later, 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:
compileJava.dependsOn(processResources)
This dependency ensures that the additional metadata is available when the annotation processor runs during compilation.
The processor picks up both classes and methods that are annotated with @ConfigurationProperties
.
The Javadoc for field values within configuration classes is used to populate the description
attribute.
You should only use simple text with @ConfigurationProperties field Javadoc, since they are not processed before being added to the JSON.
|
If the class has a single constructor with at least one parameters, one property is created per constructor parameter. Otherwise, properties are discovered through the presence of standard getters and setters with special handling for collection types (that is detected even if only a getter is present).
The annotation processor also supports the use of the @Data
, @Getter
, and @Setter
lombok annotations.
The annotation processor cannot auto-detect default values for Enum
s and Collections
s.
In the cases where a Collection
or Enum
property has a non-empty default value, manual metadata should be provided.
Consider the following class:
@ConfigurationProperties(prefix = "acme.messaging")
public class MessagingProperties {
private List<String> addresses = new ArrayList<>(Arrays.asList("a", "b"));
private ContainerType containerType = ContainerType.SIMPLE;
// ... getter and setters
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": "acme.messaging.addresses",
"defaultValue": ["a", "b"]
},
{
"name": "acme.messaging.container-type",
"defaultValue": "simple"
}
]}
Only the name
of the property is required to document additional fields with manual metadata.
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
|
Nested Properties
The annotation processor automatically considers inner classes as nested properties. Consider the following class:
@ConfigurationProperties(prefix="server")
public class ServerProperties {
private String name;
private Host host;
// ... getter and setters
public static class Host {
private String ip;
private int port;
// ... getter and setters
}
}
The preceding example produces metadata information for server.name
, server.host.ip
, and 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).
10.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.
10.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.
10.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
.
10.E.2. Spring Boot’s “JarFile” Class
The core class used to support loading nested jars is org.springframework.boot.loader.jar.JarFile
.
It lets you load jar content from a standard jar file or 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.JarFile
extends from java.util.jar.JarFile
and should work as a drop-in replacement.
The getURL()
method returns a URL
that opens a connection compatible with java.net.JarURLConnection
and can be used with Java’s URLClassLoader
.
10.E.3. Launching Executable Jars
The org.springframework.boot.loader.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 URLClassLoader
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.JarLauncher Start-Class: com.mycompany.project.MyApplication
For a war file, it would be as follows:
Main-Class: org.springframework.boot.loader.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.
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10.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 |
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Default arguments for the main method (space separated). |
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Name of main class to launch (for example, |
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Name of properties file (for example, |
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Path to properties file (for example, |
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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 fat 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 .
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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.
10.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.
10.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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10.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.
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