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Aggregating PMD reports for Multi-Module-Projects

For example, consider the following directory structure:

Project
  |-- pom.xml
  |-- Module1
  |   `-- pom.xml
  |   `-- Module 2
  |       `-- pom.xml
  |   `-- Module 3
  |       `-- pom.xml
  |-- Module4
  |   `-- pom.xml
  `-- Module5
    `-- pom.xml

Since 3.15.0 the aggregate has changed a little bit. It'll generate aggregated reports at every level. To get only an aggregated project at root level, you need to configure the pom like:

<project>
  ...
  <reporting>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-pmd-plugin</artifactId>
        <version>3.23.0</version>
        <reportSets>
          <reportSet>
            <id>aggregate</id>
            <inherited>false</inherited> <!-- don't run aggregate in child modules -->
            <reports>
              <report>aggregate-pmd</report>
              <report>aggregate-cpd</report>
            </reports>
          </reportSet>
          <reportSet>
            <id>default</id>
            <reports>
              <report>pmd</report>
              <report>cpd</report>
            </reports>
          </reportSet>
        </reportSets>
      </plugin>
    </plugins>
    ...
  </reporting>
  ...
</project>

Using The aggregate Goals

The <aggregate/> parameter doesn't make sure, that the project is compiled before executing PMD which might lead to wrong results. Therefore the report goals aggregate-pmd and aggregate-cpd have been introduced. You could define these goals in the <build/> element (using the <execution/> tag) or <reporting/> element (using the <reportSet/> tag) as shown below.

<project>
  ...
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-pmd-plugin</artifactId>
        <version>3.23.0</version>
        <configuration>
          <!-- Default configuration for all reports -->
          ...
        </configuration>
        <executions>
          <execution>
            <id>aggregate</id>
            <goals>
              <goal>aggregate-pmd</goal>
              <goal>aggregate-cpd</goal>
            </goals>
            <phase>site</phase>
            <configuration>
              <!-- Specific configuration for the aggregate report -->
              ...
            </configuration>
          </execution>
          ...
        </executions>
      </plugin>
      ...
    </plugins>
  </build>
  ...
</project>

<project>
  ...
  <reporting>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-pmd-plugin</artifactId>
        <version>3.23.0</version>
        <configuration>
          <!-- Default configuration for all reports -->
          ...
        </configuration>
        <reportSets>
          <reportSet>
            <id>non-aggregate</id>
            <configuration>
              <!-- Specific configuration for the non aggregate report -->
              ...
            </configuration>
            <reports>
              <report>pmd</report>
              <report>cpd</report>
            </reports>
          </reportSet>
          <reportSet>
            <id>aggregate</id>
            <configuration>
              <!-- Specific configuration for the aggregate report -->
              ...
            </configuration>
            <reports>
              <report>aggregate-pmd</report>
              <report>aggregate-cpd</report>
            </reports>
          </reportSet>
          ...
        </reportSets>
      </plugin>
      ...
    </plugins>
  </reporting>
  ...
</project>

Generate aggregate PMD without duplicate execution of phase test-compile

  • The standard goal aggregate-pmd invokes separate lifecyle test-compile.
  • In a CI environment you now might execute something like mvn clean deploy site site-deploy.
  • During site build the standard reports will trigger test-compile again, depending on your build this may take some time, because stuff like enforcer or generating stubs from a WDSL will be invoked again, which may lead to longer build times.
  • As of version 3.15.0 a new report is defined, aggregate-pmd-no-fork which will not trigger above phases a second time.
  • Note: This is only a problem for PMD report. CPD does not invoke a separate lifecycle.
  • Configure this in your reporting section as follows: 
    <project>
  ...
  <reporting>
    <excludeDefaults>true</excludeDefaults>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-pmd-plugin</artifactId>
        <version>3.23.0</version>
        <reportSets>
          <reportSet>
            <reports>
              <report>aggregate-pmd-no-fork</report>
              <report>aggregate-cpd</report>
            </reports>
          </reportSet>
        </reportSets>
      </plugin>
    </plugins>
  </reporting>
  ...
</project>