Both the Maven and Gradle plugin allow to generate build information containing the coordinates, name and version of the project. The plugin can also be configured to add additional properties through configuration. When such file is present, Spring Boot auto-configures a BuildProperties bean.

To generate build information with Maven, add an execution for the build-info goal:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <version>1.5.21.RELEASE</version>
            <executions>
                <execution>
                    <goals>
                        <goal>build-info</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

	Tip
	Check the Spring Boot Maven Plugin documentation for more details.

And to do the same with Gradle:

springBoot  {
    buildInfo()
}

Additional properties can be added using the DSL:

springBoot  {
    buildInfo {
        additionalProperties = [
            'foo': 'bar'
        ]
    }
}

Both Maven and Gradle allow to generate 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. Simply 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 using the gradle-git-properties plugin

plugins {
    id "com.gorylenko.gradle-git-properties" version "1.4.17"
}

	Tip
	The commit time in git.properties is expected to match the format yyyy-MM-dd’T’HH:mm:ssZ. This is the default format for both plugins listed above. Using this format allows the time to be parsed into a Date and its format when serialized to JSON to be controlled by Jackson’s date serialization configuration settings.

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 spring-boot-dependencies POM for a complete list of properties. For example, to pick a different slf4j version you would add the following:

<properties>
    <slf4j.version>1.7.5<slf4j.version>
</properties>

	Note
	This 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.

	Warning
	Each Spring Boot release is designed and tested against a specific set of third-party dependencies. Overriding versions may cause compatibility issues.

To override dependency versions in Gradle, you can specify a version as shown below:

ext['slf4j.version'] = '1.7.5'

For additional information, please refer to the Gradle Dependency Management Plugin documentation.

The spring-boot-maven-plugin can be used to create an executable ‘fat’ JAR. If you are using the spring-boot-starter-parent POM you can simply declare the plugin and your jars will be repackaged:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

If you are not using the parent POM you can still use the plugin, however, you must additionally add an <executions> section:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <version>1.5.21.RELEASE</version>
            <executions>
                <execution>
                    <goals>
                        <goal>repackage</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

See the plugin documentation for full usage details.

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 dependency.

To configure a classifier of exec in Maven, the following configuration can be used:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <classifier>exec</classifier>
            </configuration>
        </plugin>
    </plugins>
</build>

And when using Gradle, the following configuration can be used:

bootRepackage  {
    classifier = 'exec'
}

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.

	Warning
	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 unpack 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>

And to do that same with Gradle:

springBoot  {
    requiresUnpack = ['org.jruby:jruby-complete']
}

Often if you have an executable and a non-executable jar as build products, the executable version will have additional configuration files that are not needed in a library jar. E.g. the application.yml configuration file might excluded from the non-executable JAR.

Here’s how to do that in Maven:

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <classifier>exec</classifier>
            </configuration>
        </plugin>
        <plugin>
            <artifactId>maven-jar-plugin</artifactId>
            <executions>
                <execution>
                    <id>exec</id>
                    <phase>package</phase>
                    <goals>
                        <goal>jar</goal>
                    </goals>
                    <configuration>
                        <classifier>exec</classifier>
                    </configuration>
                </execution>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>jar</goal>
                    </goals>
                    <configuration>
                        <!-- Need this to ensure application.yml is excluded -->
                        <forceCreation>true</forceCreation>
                        <excludes>
                            <exclude>application.yml</exclude>
                        </excludes>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

In Gradle you can create a new JAR archive with standard task DSL features, and then have the bootRepackage task depend on that one using its withJarTask property:

jar {
    baseName = 'spring-boot-sample-profile'
    version =  '0.0.0'
    excludes = ['**/application.yml']
}

task('execJar', type:Jar, dependsOn: 'jar') {
    baseName = 'spring-boot-sample-profile'
    version =  '0.0.0'
    classifier = 'exec'
    from sourceSets.main.output
}

bootRepackage  {
    withJarTask = tasks['execJar']
}

To attach a remote debugger to a Spring Boot application started with Maven you can use the jvmArguments property of the maven plugin.

Check this example for more details.

To attach a remote debugger to a Spring Boot application started with Gradle you can use the jvmArgs property of bootRun task or --debug-jvm command line option.

build.gradle:

bootRun {
    jvmArgs "-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005"
}

Command line:

$ gradle bootRun --debug-jvm

Check Gradle Application Plugin for more details.

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:

Example:

<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>

The Ant Sample has a build.xml with a manual task that should work if you run it with

$ ant -lib <folder containing ivy-2.2.jar> clean manual

after which you can run the application with

$ java -jar target/*.jar

If you want to use Spring Boot with Java 6 there are a small number of configuration changes that you will have to make. The exact changes depend on your application’s functionality.