Execute Maven plugin goal on parent module, but not on children

Question

We have a multi-module maven project that uses a profile that defines a buildnumber-maven-plugin to increment a build number and then check it into source control.

If I define the plugin in the parent pom.xml it executes for all the child builds as well.

Here's my parent pom.xml

<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 
                      http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.webwars</groupId>
  <artifactId>parent</artifactId>
  <packaging>pom</packaging>
  <properties>
    <buildNumber.properties>${basedir}/../parent/buildNumber.properties</buildNumber.properties>
  </properties>
  <version>1.0-SNAPSHOT</version>
  <name>Parent Project</name>
  <profiles>
    <profile>
      <id>release</id>
      <build>
        <plugins>
          <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
              <debug>false</debug>
              <optimize>true</optimize>
            </configuration>
          </plugin>
          <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>buildnumber-maven-plugin</artifactId>
            <version>1.0-beta-3</version>
            <executions>
              <execution>
                <phase>validate</phase>
                <goals>
                  <goal>create</goal>
                </goals>
              </execution>
            </executions>
            <configuration>
              <buildNumberPropertiesFileLocation>${buildNumber.properties}</buildNumberPropertiesFileLocation>
              <getRevisionOnlyOnce>true</getRevisionOnlyOnce>
              <doCheck>false</doCheck>
              <doUpdate>false</doUpdate>
              <format>{0, number}</format>
              <items>
                <item>buildNumber</item>
              </items>
            </configuration>
          </plugin>
          <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-scm-plugin</artifactId>
            <executions>
              <execution>
                <phase>install</phase>
                <goals>
                  <goal>checkin</goal>
                </goals>
              </execution>
            </executions>
            <configuration>
              <basedir>${basedir}</basedir>
              <includes>buildNumber.properties</includes>
              <message>[Automated checkin] of ${basedir} Build version: ${major.version}.${minor.version}.${buildNumber}</message>
              <developerConnectionUrl>...</developerConnectionUrl>
            </configuration>
          </plugin>         
        </plugins>
      </build>
    </profile>
  </profiles>

  <modules>

    <module>../common</module>
    <module>../data</module>
    <module>../client</module>
    <module>../webplatform</module>
  </modules>
 ...
</project>

Answer 1

As documented in the Plugins section of the pom reference:

Beyond the standard coordinate of groupId:artifactId:version, there are elements which configure the plugin or this builds interaction with it.

• inherited: true or false, whether or not this plugin configuration should apply to POMs which inherit from this one.

So just add <inherited>false</inherited> to the buildnumber-maven-plugin configuration to avoid inheritance in children POMs:

      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>buildnumber-maven-plugin</artifactId>
        <version>1.0-beta-3</version>
        <inherited>false</inherited>
        ...
      </plugin>

Answer 2

You can add <inherited>false</inherited> to the plugin configuration to avoid inheritance in children POMs:

      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>buildnumber-maven-plugin</artifactId>
        <version>1.0-beta-3</version>
        <inherited>false</inherited>
        ...
      </plugin>

Or, if your plugin has multiple executions, you can control which executions are inherited and which are not by adding the inherited tag to the execution body:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-antrun-plugin</artifactId>
    <executions>
      <execution>
        <id>parent-only</id>
        <phase>initialize</phase>
        <inherited>false</inherited>
        <configuration>
          <target>
            <echo message="Echoed only by this module."/>
          </target>
        </configuration>
        <goals>
          <goal>run</goal>
        </goals>
      </execution>
      <execution>
        <id>all-modules</id>
        <phase>initialize</phase>
        <inherited>true</inherited> <!-- Defaults to true, so you could leave this line out -->
        <configuration>
          <target>
            <echo message="Echoed in this module and each child module."/>
          </target>
        </configuration>
        <goals>
          <goal>run</goal>
        </goals>
      </execution>
    </executions>
  </plugin>

Answer 3

There is a built-in maven option:

mvn --help
...
-N,--non-recursive    Do not recurse into sub-projects

Answer 4

Just an addition to the great answers here: note that per-execution inheritance is broken in Maven 2: http://jira.codehaus.org/browse/MNG-3959

Answer 5

If the plugin is custom one and you have access to plugin MOJO code, you can mark the plugin as aggregator; if the expected behavior is applicable for all projects where plugin is to be used.

As mentioned in Mojo API Specification ,

Flags this Mojo to run it in a multi module way, i.e. aggregate the build with the set of projects listed as modules.

Example,

@Mojo(name = "createHF", inheritByDefault = false, aggregator = true)
public class CreateHFMojo extends AbstractMojo {

..

public void execute() throws MojoExecutionException, MojoFailureException {
 ....
}

..

}

Detailed example on github.