Gestion des dépendances multi-module avec plug-in Maven Assembly

Question

J'utilise le plugin de montage Maven pour créer un assemblage pour mon projet multi-module. Il existe deux applications distinctes construites à partir de ce projet multi-module, chacun ayant un ensemble de dépendances séparé. J'ai fait un descripteur d'assemblage personnalisé qui assemble deux répertoires (pour chaque application) avec des bâtiments de module et leurs dépendances respectives. Il fait tout ce qui va bien mais une chose - il met des dépendances pour les deux modules à l'assemblage de chacun.

Ce qui suit est une version simplifiée de mon projet, qui a exactement le même comportement.

Considérons un projet composé de deux modules et d'un module d'assemblage:

APP
  module1
  module2
  assembly

J'ai ajouté des dépendances purement pour la démonstration:

com.test.app:module1:jar:1.0
\- commons-cli:commons-cli:jar:1.2:compile

com.test.app:module2:jar:1.0
\- commons-daemon:commons-daemon:jar:1.0.8:compile

Voici le parent POM:

<project>
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.test</groupId>
  <artifactId>app</artifactId>
  <version>1.0</version>
  <packaging>pom</packaging>

  <modules>
    <module>module1</module>
    <module>module2</module>
    <module>assembly</module>
  </modules>
</project>

module1 pom:

<project>
  <parent>
    <groupId>com.test</groupId>
    <artifactId>app</artifactId>
    <version>1.0</version>
  </parent>

  <modelVersion>4.0.0</modelVersion>

  <groupId>com.test.app</groupId>
  <artifactId>module1</artifactId>
  <version>1.0</version>
  <packaging>jar</packaging>

  <dependencies>
    <dependency>
      <groupId>commons-cli</groupId>
      <artifactId>commons-cli</artifactId>
      <version>1.2</version>
    </dependency>
  </dependencies>
</project>

Module2 POM:

<project>
  <parent>
    <groupId>com.test</groupId>
    <artifactId>app</artifactId>
    <version>1.0</version>
  </parent>

  <modelVersion>4.0.0</modelVersion>

  <groupId>com.test.app</groupId>
  <artifactId>module2</artifactId>
  <version>1.0</version>
  <packaging>jar</packaging>

  <dependencies>
    <dependency>
      <groupId>commons-daemon</groupId>
      <artifactId>commons-daemon</artifactId>
      <version>1.0.8</version>
    </dependency>
  </dependencies>
</project>

Assemblage POM:

<project>
  <parent>
    <groupId>com.test</groupId>
    <artifactId>app</artifactId>
    <version>1.0</version>
  </parent>

  <modelVersion>4.0.0</modelVersion>

  <groupId>com.test.app</groupId>
  <artifactId>assembly</artifactId>
  <version>1.0</version>
  <packaging>pom</packaging>

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>2.2.2</version>

        <executions>
          <execution>
            <id>make-assembly</id>
            <phase>package</phase>

            <goals>
              <goal>single</goal>
            </goals>
          </execution>
        </executions>

        <configuration>
          <appendAssemblyId>false</appendAssemblyId>

          <descriptors>
            <descriptor>src/main/assembly/descriptor.xml</descriptor>
          </descriptors>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

et enfin, le descripteur d'assemblage:

<assembly>
  <id>distribution</id>
  <includeBaseDirectory>false</includeBaseDirectory>

  <formats>
    <format>dir</format>
  </formats>

  <moduleSets>
    <moduleSet>
      <useAllReactorProjects>true</useAllReactorProjects>

      <includes>
        <include>com.test.app:module1:jar</include>
      </includes>

      <binaries>
        <outputDirectory>module1</outputDirectory>
        <unpack>false</unpack>

        <dependencySets>
          <dependencySet>
            <unpack>false</unpack>
          </dependencySet>
        </dependencySets>
      </binaries>
    </moduleSet>

    <moduleSet>
      <useAllReactorProjects>true</useAllReactorProjects>

      <includes>
        <include>com.test.app:module2:jar</include>
      </includes>

      <binaries>
        <outputDirectory>module2</outputDirectory>
        <unpack>false</unpack>

        <dependencySets>
          <dependencySet>
            <unpack>false</unpack>
          </dependencySet>
        </dependencySets>
      </binaries>
    </moduleSet>
  </moduleSets>
</assembly>

Comme vous pouvez le constater, l'assemblage est lié à la phase d'emballage. Donc, quand j'exécute

mvn package

du répertoire parent, j'ai l'assemblage suivant

module1/
  commons-cli-1.2.jar
  commons-daemon-1.0.8.jar
  module1-1.0.jar
module2/
  commons-cli-1.2.jar
  commons-daemon-1.0.8.jar
  module2-1.0.jar

Fondamentalement, le problème ici est que le module1 ne dépend pas du démon Commons-Daemon, mais le plugin d'assemblage a inclus la dépendance. De même, avec Module2 et Commons-CLI.

Quelqu'un peut-il expliquer pourquoi le plugin de montage se comporte de cette façon?

Quel serait une solution?

Answer 1

I've always had similar experiences using the assembly plugin with multi-module projects where the end result wasn't what I expected. I hope someone else can provide a more accurate answer as to why that's happening and how best to use those two concepts in tandem.

That said, a possible work-around would be to have module1 and module2 generate their own assembly artifacts which contain their respective jars and dependencies. Then you can modify the assembly sub-module pom file to have dependencies on the generated distribution artifacts from its sibling modules and then unpack those into a new assembly.

In both Module1 and Module2's pom files you can add an assembly plugin configuration to your package phase much like you did with the assembly sub-module.

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>2.2.2</version>

        <executions>
          <execution>
            <id>make-assembly</id>
            <phase>package</phase>
            <goals>
              <goal>single</goal>
            </goals>
          </execution>
        </executions>

        <configuration>
          <descriptors>
            <descriptor>src/main/assembly/descriptor.xml</descriptor>
          </descriptors>
        </configuration>
      </plugin>
    </plugins>
  </build>

Module1 would have a src/main/assembly/descriptor.xml like this

<assembly>
  <id>distribution</id>
  <includeBaseDirectory>false</includeBaseDirectory>

  <formats>
    <format>zip</format>
  </formats>

  <dependencySets>
    <dependencySet>
      <outputDirectory>module1</outputDirectory>
      <unpack>false</unpack>
    </dependencySet>
  </dependencySets>
</assembly>

And Module2 will have a similar src/main/assembly/descriptor.xml

<assembly>
  <id>distribution</id>
  <includeBaseDirectory>false</includeBaseDirectory>

  <formats>
    <format>zip</format>
  </formats>

  <dependencySets>
    <dependencySet>
      <outputDirectory>module2</outputDirectory>
      <unpack>false</unpack>
    </dependencySet>
  </dependencySets>
</assembly>

Then in the assembly/pom.xml you would add the Module 1 and 2 zip artifacts as dependencies

  <dependencies>
    <dependency>
      <groupId>com.test.app</groupId>
      <artifactId>module1</artifactId>
      <version>1.0</version>
      <type>zip</type>
      <classifier>distribution</classifier>
    </dependency>
    <dependency>
      <groupId>com.test.app</groupId>
      <artifactId>module2</artifactId>
      <version>1.0</version>
      <type>zip</type>
      <classifier>distribution</classifier>
    </dependency>
  </dependencies>

...and trim up the assembly/src/main/assembly/descriptor.xml file to look like this

<assembly>
  <id>distribution</id>
  <includeBaseDirectory>false</includeBaseDirectory>

  <formats>
    <format>dir</format>
  </formats>

  <dependencySets>
    <dependencySet>
      <useTransitiveDependencies>false</useTransitiveDependencies>
      <unpack>true</unpack>
    </dependencySet>
  </dependencySets>

</assembly>

Like I said this would be one possible work around and unfortunately adds a significant amount of additional XML configuration to your build process. But it works.