Maven – Example: Maven 3 lifecycle extension

Example: Using Maven 3 lifecycle extension

Lifecyle Participation

You can extend multiple classes depending on your needs:

Build your extension

Create a Maven project with a dependency on org.apache.maven:maven-core:3.8.1 and other dependencies:

    <groupId>org.apache.maven.extensions</groupId>
    <artifactId>beer-maven-lifecycle</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependency>
      <groupId>org.apache.maven</groupId>
      <artifactId>maven-core</artifactId>
      <version>3.8.1</version>
    </dependency>

    <!-- dependency for plexus annotation -->
    <dependency>
      <groupId>org.codehaus.plexus</groupId>
      <artifactId>plexus-component-annotations</artifactId>
      <version>1.7.1</version>
    </dependency>

Create your extension class

// your extension must be a "Plexus" component so mark it with the annotation
@Component( role = AbstractMavenLifecycleParticipant.class, hint = "beer")
public class BeerMavenLifecycleParticipant extends AbstractMavenLifecycleParticipant
{

    @Override
    public void afterSessionStart( MavenSession session )
        throws MavenExecutionException
    {
      // start the beer machine
    }


    @Override
    public void afterProjectsRead( MavenSession session )
        throws MavenExecutionException
    {
      // ask a beer to the machine
    }

}

Generate plexus metadata during the build of your extension jar:

  <build>
    ...
    <plugins>
      ...
      <plugin>
        <groupId>org.codehaus.plexus</groupId>
        <artifactId>plexus-component-metadata</artifactId>
        <version>1.7.1</version>
        <executions>
          <execution>
            <goals>
              <goal>generate-metadata</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
      ...
    </plugins>
    ...
  </build>

Use your extension in your build(s)

You have 3 ways to use your extension within your builds:

add your extension jar in ${maven.home}/lib/ext,
add it as a build extension in your pom,
(since Maven 3.3.1) configure your extension in .mvn/extensions.xml.

NOTE: if you use the build extension mechanism, the method afterSessionStart won't be called since the extension is loaded later in the build

To use a build extension in your project, declare it in your pom as:

   <build>
     ...
     <extensions>
       ...
       <extension>
         <groupId>org.apache.maven.extensions</groupId>
         <artifactId>beer-maven-lifecycle</artifactId>
         <version>1.0-SNAPSHOT</version>
       </extension>
       ...
     </extensions>
    ...
   </build>