Maven Assembly: Error There is more than one file in input

I have a Maven project that builds an Ear. We then need to package that ear up into a zip file with a few other files (shell scripts, etc.).

My project looks like this:

foo-parent
- foo-jar
- foo-sar
- foo-ear

The jar, sar, and ears all build. The ear contains the jar and the sar that from the other submodules. Now, all I have to do is package that ear with a few other files and zip it up.

Originally, I put the assembly in foo-parent, but then ran into the problem that foo-parent was running the package phase on itself before building the jar, sar, and ear. Reading up a bit, I was told to put the assembly in one of the submodules, so I picked foo-ear.

I am now getting the error:

Failed to execute goal org.apache.maven.plugins:maven-assembly-plugin:2.6:single
(foo-services-zip) on project foo-ear: Failed to create assembly: 
Error creating assembly archive foo-services-dist: There is more
than one file in input.

I am not sure what There is more than one file in input means.

My foo-ear POM looks like this:

<project>
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>com.vegicorp.foo</groupId>
        <artifactId>foo-parent</artifactId>
        <version>1.0.0</version>
        <relativePath>..</relativePath>
    </parent>
    <artifactId>foo-ear</artifactId>
    <packaging>ear</packaging>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-ear-plugin</artifactId>
                <version>2.10.1</version>
                [...]
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-assembly-plugin</artifactId>
                <executions>
                    <execution>
                        <id>build-foo-zip</id>
                        <phase>package</phase>
                        <goals>
                            <goal>single</goal>
                        </goals>
                        <configuration>
                            <descriptors>
                                <descriptor>src/assembly/foo-zip.xml</descriptor>
                            </descriptors>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
    <dependencies>
    [...]
    </dependencies>
</project>

My src/assembly/foo-zip.xml file looks like this:

<assembly>
    <id>foo-zip</id>
    <formats>
        <format>gzip</format>
    </formats>
    <includeBaseDirectory>true</includeBaseDirectory>
    <fileSets>
        <fileSet>
            <directory>src/dist-files</directory>
            <outputDirectory></outputDirectory>
        </fileSet>
    </fileSets>
    <moduleSets>
        <moduleSet>
            <useAllReactorProjects>true</useAllReactorProjects>
            <includes>
                <include>com.vegicorp.foo:foo-ear</include>
            </includes>
            <binaries>
                 <includeDependencies>false</includeDependencies>
                <outputDirectory>data/ear-dir</outputDirectory>
                <unpack>true</unpack>
            </binaries>
        </moduleSet>
    </moduleSets>
</assembly>

Yes, I know I could use just <file> or another <fileSet>, but the ear needs to be unpacked inside of the gzip file, so I need to use <moduleSets>. I am not sure understand how <binary> or how <moduleSets> works, and I believe my error is somewhere in that configuration.

Solution

Found the problem. The assembly file had a format of gzip. This is actually an invalid format, but the Assembly still takes it. If you have more than a single file in your assembly, the assembly will fail. I changed the format to zip and everything works -- including the module stuff which I thought was the issue.

This maybe a bug in the Assembly plugin. I'll have to investigate.