The Spring Boot Gradle Plugin provides Spring Boot support in Gradle, allowing you to
package executable jar or war archives, run Spring Boot applications and use the
dependency management provided by spring-boot-dependencies
.
To use the Spring Boot Gradle Plugin configure it using the plugins
block:
plugins { id 'org.springframework.boot' version '1.5.18.RELEASE' }
The spring-boot
plugin automatically applies the
Dependency Management Plugin and configures it to import
the spring-boot-starter-parent
bom. This provides a similar dependency management
experience to the one that is enjoyed by Maven users. For example, it allows you to omit
version numbers when declaring dependencies that are managed in the bom. To make use of
this functionality, simply declare dependencies in the usual way, but leave the version
number empty:
dependencies { compile("org.springframework.boot:spring-boot-starter-web") compile("org.thymeleaf:thymeleaf-spring4") compile("nz.net.ultraq.thymeleaf:thymeleaf-layout-dialect") }
Note | |
---|---|
The version of the |
To learn more about the capabilities of the Dependency Management Plugin, please refer to its documentation.
Once the spring-boot
plugin has been applied to your project it will automatically
attempt to rewrite archives to make them executable using the
bootRepackage
task. You
should configure your project to build a jar or war (as appropriate) in the usual way.
The main class that you want to launch can either be specified using a configuration
option, or by adding a Main-Class
attribute to the manifest. If you don’t specify a
main class the plugin will search for a class with a
public static void main(String[] args)
method.
Tip | |
---|---|
Check Section 67.6, “Repackage configuration” for a full list of configuration options. |
To build and run a project artifact, you can type the following:
$ gradle build $ java -jar build/libs/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 belonging to the war plugin’s
providedRuntime
configuration, e.g.:
... apply plugin: 'war' war { baseName = 'myapp' version = '0.5.0' } repositories { jcenter() maven { url "https://repo.spring.io/libs-snapshot" } } dependencies { compile("org.springframework.boot:spring-boot-starter-web") providedRuntime("org.springframework.boot:spring-boot-starter-tomcat") ... }
Tip | |
---|---|
See the “Section 86.1, “Create a deployable war file”” section for more details on how to create a deployable war file. |
To run a project in place without building a jar first you can use the “bootRun” task:
$ gradle bootRun
If devtools
has been added to your project
it will automatically monitor your application for changes. Alternatively, you can also
run the application so that your static classpath resources (i.e. in src/main/resources
by default) are reloadable in the live application, which can be helpful at development
time.
bootRun { addResources = true }
Making static classpath resources reloadable means that bootRun
does not use the output
of the processResources
task, i.e., when invoked using bootRun
, your application will
use the resources in their unprocessed form.
The gradle plugin automatically extends your build script DSL with a springBoot
element
for global configuration of the Boot plugin. Set the appropriate properties as you would
with any other Gradle extension (see below for a list of configuration options):
springBoot { backupSource = false }
The plugin adds a bootRepackage
task which you can also configure directly, e.g.:
bootRepackage {
mainClass = 'demo.Application'
}
The following configuration options are available:
Name | Description |
---|---|
| Boolean flag to switch the repackager off (sometimes useful if you want the other Boot features but not this one) |
| The main class that should be run. If not specified, and you have applied the application
plugin, the |
| A file name segment (before the extension) to add to the archive, so that the original is
preserved in its original location. Defaults to |
| The name or value of the |
| The name of the custom configuration which is used to populate the nested lib directory (without specifying this you get all compile and runtime dependencies). |
| Boolean flag to indicate if jar files are fully executable on Unix like operating
systems. Defaults to |
| The embedded launch script to prepend to the front of the jar if it is fully executable. If not specified the 'Spring Boot' default script will be used. |
| Additional properties that to be expanded in the launch script. The default script
supports a |
| Boolean flag to indicate if the devtools jar should be excluded from the repackaged
archives. Defaults to |
Sometimes it may be more appropriate to not package default dependencies resolved from
compile
, runtime
and provided
scopes. If the created executable jar file
is intended to be run as it is, you need to have all dependencies nested inside it;
however, if the plan is to explode a jar file and run the main class manually, you may already
have some of the libraries available via CLASSPATH
. This is a situation where
you can repackage your jar with a different set of dependencies.
Using a custom
configuration will automatically disable dependency resolving from
compile
, runtime
and provided
scopes. Custom configuration can be either
defined globally (inside the springBoot
section) or per task.
task clientJar(type: Jar) { appendix = 'client' from sourceSets.main.output exclude('**/*Something*') } task clientBoot(type: BootRepackage, dependsOn: clientJar) { withJarTask = clientJar customConfiguration = "mycustomconfiguration" }
In above example, we created a new clientJar
Jar task to package a customized
file set from your compiled sources. Then we created a new clientBoot
BootRepackage task and instructed it to work with only clientJar
task and
mycustomconfiguration
.
configurations {
mycustomconfiguration.exclude group: 'log4j'
}
dependencies {
mycustomconfiguration configurations.runtime
}
The configuration that we are referring to in BootRepackage
is a normal
Gradle
configuration. In the above example we created a new configuration named
mycustomconfiguration
instructing it to derive from a runtime
and exclude the log4j
group. If the clientBoot
task is executed, the repackaged boot jar will have all
dependencies from runtime
but no log4j
jars.
The following configuration options are available:
Name | Description |
---|---|
| The main class that should be run by the executable archive. |
| The name of the provided configuration (defaults to |
| If the original source archive should be backed-up before being repackaged (defaults
to |
| The name of the custom configuration. |
| The type of archive, corresponding to how the dependencies are laid out inside (defaults to a guess based on the archive type). See available layouts for more details. |
| A layout factory that can be used if a custom layout is required. Alternative layouts
can be provided by 3rd parties. Layout factories are only used when |
| A list of dependencies (in the form “groupId:artifactId” that must be unpacked from fat jars in order to run. Items are still packaged into the fat jar, but they will be automatically unpacked when it runs. |
The layout
attribute configures the format of the archive and whether the bootstrap
loader should be included or not. The following layouts are available:
Name | Description | Executable |
---|---|---|
| Regular executable JAR layout. | Yes |
| Executable
WAR layout.
| Yes |
| Similar to | Yes |
| Bundle dependencies (excluding those with | No |
| Bundle all dependencies and project resources. | No |
If you have custom requirements for how to arrange the dependencies and loader classes
inside the repackaged jar, you can use a custom layout. Any library which defines one
or more LayoutFactory
implementations can be added to the build script dependencies
and then the layout factory becomes available in the springBoot
configuration.
For example:
buildscript { repositories { mavenCentral() } dependencies { classpath("org.springframework.boot:spring-boot-gradle-plugin:1.5.18.RELEASE") classpath("com.example:custom-layout:1.0.0") } } springBoot { layoutFactory = new com.example.CustomLayoutFactory() }
Note | |
---|---|
If there is only one custom |
When spring-boot
is applied to your Gradle project a default task named bootRepackage
is created automatically. The bootRepackage
task depends on Gradle assemble
task, and
when executed, it tries to find all jar artifacts whose qualifier is empty (i.e. tests and
sources jars are automatically skipped).
Due to the fact that bootRepackage
finds 'all' created jar artifacts, the order of
Gradle task execution is important. Most projects only create a single jar file, so
usually this is not an issue; however, if you are planning to create a more complex
project setup, with custom Jar
and BootRepackage
tasks, there are few tweaks to
consider.
If you are 'just' creating custom jar files from your project you can simply disable
default jar
and bootRepackage
tasks:
jar.enabled = false bootRepackage.enabled = false
Another option is to instruct the default bootRepackage
task to only work with a
default jar
task.
bootRepackage.withJarTask = jar
If you have a default project setup where the main jar file is created and repackaged,
'and' you still want to create additional custom jars, you can combine your custom
repackage tasks together and use dependsOn
so that the bootJars
task will run after
the default bootRepackage
task is executed:
task bootJars bootJars.dependsOn = [clientBoot1,clientBoot2,clientBoot3] build.dependsOn(bootJars)
All the above tweaks are usually used to avoid situations where an already created boot jar is repackaged again. Repackaging an existing boot jar will not break anything, but you may find that it includes unnecessary dependencies.
If you are declaring
dependencies without versions and you want to publish artifacts to a Maven repository
you will need to configure the Maven publication with details of Spring Boot’s
dependency management. This can be achieved by configuring it to publish poms that
inherit from spring-boot-starter-parent
or that import dependency management from
spring-boot-dependencies
. The exact details of this configuration depend on how you’re
using Gradle and how you’re trying to publish the artifacts.
The following is an example of configuring Gradle to generate a pom that inherits
from spring-boot-starter-parent
. Please refer to the
Gradle User Guide for further information.
uploadArchives { repositories { mavenDeployer { pom { project { parent { groupId "org.springframework.boot" artifactId "spring-boot-starter-parent" version "1.5.18.RELEASE" } } } } } }
The following is an example of configuring Gradle to generate a pom that imports
the dependency management provided by spring-boot-dependencies
. Please refer to the
Gradle User Guide for
further information.
uploadArchives { repositories { mavenDeployer { pom { project { dependencyManagement { dependencies { dependency { groupId "org.springframework.boot" artifactId "spring-boot-dependencies" version "1.5.18.RELEASE" type "pom" scope "import" } } } } } } } }