This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Boot 3.3.2! |
Build
Spring Boot includes build plugins for Maven and Gradle. This section answers common questions about these plugins.
Generate Build Information
Both the Maven plugin and the Gradle plugin allow generating build information containing the coordinates, name, and version of the project.
The plugins can also be configured to add additional properties through configuration.
When such a file is present, Spring Boot auto-configures a BuildProperties
bean.
To generate build information with Maven, add an execution for the build-info
goal, as shown in the following example:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>3.4.0-M1</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. |
Generate Git Information
Both Maven and Gradle allow generating a git.properties
file containing information about the state of your git
source code repository when the project was built.
For Maven users, the spring-boot-starter-parent
POM includes a pre-configured plugin to generate a git.properties
file.
To use it, add the following declaration for the Git Commit Id Plugin
to your POM:
<build>
<plugins>
<plugin>
<groupId>io.github.git-commit-id</groupId>
<artifactId>git-commit-id-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
Gradle users can achieve the same result by using the gradle-git-properties
plugin, as shown in the following example:
plugins {
id "com.gorylenko.gradle-git-properties" version "2.4.1"
}
Both the Maven and Gradle plugins allow the properties that are included in git.properties
to be configured.
The commit time in git.properties is expected to match the following format: yyyy-MM-dd’T’HH:mm:ssZ .
This is the default format for both plugins listed above.
Using this format lets the time be parsed into a Date and its format, when serialized to JSON, to be controlled by Jackson’s date serialization configuration settings.
|
Customize Dependency Versions
The spring-boot-dependencies
POM manages the versions of common dependencies.
The Spring Boot plugins for Maven and Gradle allow these managed dependency versions to be customized using build properties.
Each Spring Boot release is designed and tested against this specific set of third-party dependencies. Overriding versions may cause compatibility issues. |
To override dependency versions with Maven, see Using the Plugin in the Maven plugin’s documentation.
To override dependency versions in Gradle, see Customizing Managed Versions in the Gradle plugin’s documentation.
Create an Executable JAR with Maven
The spring-boot-maven-plugin
can be used to create an executable “fat” JAR.
If you use the spring-boot-starter-parent
POM, you can declare the plugin and your jars are repackaged as follows:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
If you do not use the parent POM, you can still use the plugin.
However, you must additionally add an <executions>
section, as follows:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<version>3.4.0-M1</version>
<executions>
<execution>
<goals>
<goal>repackage</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
See the plugin documentation for full usage details.
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>
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>
Create a Non-executable JAR with Exclusions
Often, if you have an executable and a non-executable jar as two separate build products, the executable version has additional configuration files that are not needed in a library jar.
For example, the application.yaml
configuration file might be excluded from the non-executable JAR.
In Maven, the executable jar must be the main artifact and you can add a classified jar for the library, as follows:
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<executions>
<execution>
<id>lib</id>
<phase>package</phase>
<goals>
<goal>jar</goal>
</goals>
<configuration>
<classifier>lib</classifier>
<excludes>
<exclude>application.yaml</exclude>
</excludes>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
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.
Build an Executable Archive From Ant without Using spring-boot-antlib
To build with Ant, you need to grab dependencies, compile, and then create a jar or war archive.
To make it executable, you can either use the spring-boot-antlib
module or you can follow these instructions:
-
If you are building a jar, package the application’s classes and resources in a nested
BOOT-INF/classes
directory. If you are building a war, package the application’s classes in a nestedWEB-INF/classes
directory as usual. -
Add the runtime dependencies in a nested
BOOT-INF/lib
directory for a jar orWEB-INF/lib
for a war. Remember not to compress the entries in the archive. -
Add the
provided
(embedded container) dependencies in a nestedBOOT-INF/lib
directory for a jar orWEB-INF/lib-provided
for a war. Remember not to compress the entries in the archive. -
Add the
spring-boot-loader
classes at the root of the archive (so that theMain-Class
is available). -
Use the appropriate launcher (such as
JarLauncher
for a jar file) as aMain-Class
attribute in the manifest and specify the other properties it needs as manifest entries — principally, by setting aStart-Class
property.
The following example shows how to build an executable archive with Ant:
<target name="build" depends="compile">
<jar destfile="target/${ant.project.name}-${spring-boot.version}.jar" compress="false">
<mappedresources>
<fileset dir="target/classes" />
<globmapper from="*" to="BOOT-INF/classes/*"/>
</mappedresources>
<mappedresources>
<fileset dir="src/main/resources" erroronmissingdir="false"/>
<globmapper from="*" to="BOOT-INF/classes/*"/>
</mappedresources>
<mappedresources>
<fileset dir="${lib.dir}/runtime" />
<globmapper from="*" to="BOOT-INF/lib/*"/>
</mappedresources>
<zipfileset src="${lib.dir}/loader/spring-boot-loader-jar-${spring-boot.version}.jar" />
<manifest>
<attribute name="Main-Class" value="org.springframework.boot.loader.launch.JarLauncher" />
<attribute name="Start-Class" value="${start-class}" />
</manifest>
</jar>
</target>