plugins - Maven assembly - Error reading assemblies

Question

I have defined a personalized jar-with-dependencies assembly descriptor. However, when I execute it with mvn assembly:assembly, I get :

...
[INFO] META-INF/ already added, skipping
[INFO] META-INF/MANIFEST.MF already added, skipping
[INFO] javax/ already added, skipping
[INFO] META-INF/ already added, skipping
[INFO] META-INF/MANIFEST.MF already added, skipping
[INFO] META-INF/maven/ already added, skipping
[INFO] [assembly:assembly {execution: default-cli}]
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Error reading assemblies: No assembly descriptors found.

My jar-with-dependencies.xml is in src/main/resources/assemblies/.

My assembly descriptor is the following :

<?xml version='1.0' encoding='UTF-8'?>
<assembly>
    <id>jar-with-dependencies</id>
    <formats>
        <format>jar</format>
    </formats>

    <dependencySets>
        <dependencySet>
            <scope>runtime</scope>
            <unpack>true</unpack>
            <unpackOptions>
                <excludes>
                    <exclude>**/LICENSE*</exclude>
                    <exclude>**/README*</exclude>
                </excludes>
            </unpackOptions>
        </dependencySet>
    </dependencySets>

    <fileSets>
        <fileSet>
            <directory>${project.build.outputDirectory}</directory>
            <outputDirectory>/</outputDirectory>
        </fileSet>
        <fileSet>
            <directory>src/main/resources/META-INF/services</directory>
            <outputDirectory>META-INF/services</outputDirectory>
        </fileSet>
    </fileSets>

</assembly>

And my project pom.xml is :

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-assembly-plugin</artifactId>
    <version>2.2-beta-5</version>
    <executions>
        <execution>
            <id>jar-with-dependencies</id>
            <phase>package</phase>
            <goals>
                <goal>single</goal>
            </goals>
            <configuration>
                <descriptors>
                    <descriptor>jar-with-dependencies.xml</descriptor>
                </descriptors>
                <archive>
                    <manifest>
                        <mainClass>org.my.app.HowTo</mainClass>
                    </manifest>
                </archive>
            </configuration>
        </execution>
    </executions>
</plugin>

When mvn assembly:assembly is performed, dependencies are unpacked and I get the previous error when unpack has finished.

Moreover, if I execute mvn -e assembly:assembly it is say that no descriptors has been found, however it try to unpack dependencies and a JAR with dependencies is created but it doesn't contain META-INF/services/* as specified in descriptor :

[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Error reading assemblies: No assembly descriptors found.

[INFO] ------------------------------------------------------------------------
[INFO] Trace
org.apache.maven.lifecycle.LifecycleExecutionException: Error reading assemblies: No assembly descriptors found.
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:719)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeStandaloneGoal(DefaultLifecycleExecutor.java:569)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:539)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:284)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
    at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
    at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
    at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
    at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: org.apache.maven.plugin.MojoExecutionException: Error reading assemblies: No assembly descriptors found.
    at org.apache.maven.plugin.assembly.mojos.AbstractAssemblyMojo.execute(AbstractAssemblyMojo.java:356)
    at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694)
    ... 17 more
Caused by: org.apache.maven.plugin.assembly.io.AssemblyReadException: No assembly descriptors found.
    at org.apache.maven.plugin.assembly.io.DefaultAssemblyReader.readAssemblies(DefaultAssemblyReader.java:206)
    at org.apache.maven.plugin.assembly.mojos.AbstractAssemblyMojo.execute(AbstractAssemblyMojo.java:352)
    ... 19 more

I don't see my error. Does someone has a solution ?

Answer 1

There are two problems here. First, when using your own descriptor, you must specify the path to your customized descriptor file (by the way, you can use any location but putting the descriptor in src/main/resources is maybe not the best choice, you don't really want the descriptor to be packaged in your application, I'd use the standard location which is src/main/assembly as mentioned in this page).

<descriptors>
  <descriptor>src/main/assembly/jar-with-dependencies.xml</descriptor>
</descriptors>

Second, your configuration element is currently inside an execution block and is thus specific to this execution. In other words, it won't apply if you run assembly:assembly on the command line. So, if you want to call assembly:assembly with a custom descriptor, either use:

mvn assembly:assembly -Ddescriptor=path/to/descriptor.xml

Or move the configuration outside the execution element (to make the configuration global):

<project>
  ...
  <build>
    ...
    <plugins>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>2.2-beta-5</version>
        <configuration>
          <descriptors>
            <descriptor>path/to/descriptor.xml</descriptor>
          </descriptors>
          ...
        </configuration>
      </plugin>
     </plugins>
     ...
   </build>
   ...
</project>