Maven - Depend on assembled zip

I'm trying to have a Project B pull down (and unpack) a ZIP built by Project A and deployed to a remote repository.

The ZIP is created and attached using the maven-assembly-plugin, with packaging type pom:

<artifactId>project-a</artifactId>
<name>ZIP</name>
<description>Used by Project B</description>
<packaging>pom</packaging>

...

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-assembly-plugin</artifactId>
  <executions>
    <execution>
      <id>distribution-package</id>
      <phase>package</phase>
      <goals>
        <goal>single</goal>
      </goals>
      <configuration>
        <descriptors>
          <descriptor>src/main/assembly/scripts.xml</descriptor>
        </descriptors>
        <tarLongFileMode>gnu</tarLongFileMode>
      </configuration>
    </execution>
  </executions>
</plugin>

Attempting to pull it down from Project B's pom with the maven-dependency-plugin:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-dependency-plugin</artifactId>
  <executions>
    <execution>
      <id>copy-scripts</id>
      <phase>package</phase>
      <goals>
        <goal>copy</goal>
      </goals>
      <configuration>
        <outputDirectory>${basedir}/target/staging</outputDirectory>
        <stripVersion>true</stripVersion>
        <artifactItems>
          <artifactItem>
            <groupId>...</groupId>
            <artifactId>...</artifactId>
            <version>...</version>
            <overWrite>true</overWrite>
            <type>zip</type>
          </artifactItem>
        </artifactItems>
      </configuration>
    </execution>
  </executions>
</plugin>

fails with: [ERROR] Failed to execute goal on project ...: Could not resolve dependencies for project group:artifact:pom:version: Could not find artifact group:project-a:zip:version in nexus (http://...:8081/nexus/content/groups/public) -> [Help 1]

I would assume this is because I specified Project A's packaging as pom and not zip, however I can't specify Project A as packaging type zip because it results in:

[ERROR]     Unknown packaging: zip @ line 13, column 13

Am I doing something wrong here or is this simply not possible? I just have a bunch of files that I want to bundle up into an artifact and allow multiple other projects to download and unpack them for use. Open to different suggestions...

I've also checked to make sure that the assembled zip is indeed in the nexus.

UPDATED WITH ANSWER

For anyone else's benefit, what I was missing is that the <classifier> of the dependency has to match the <id> of the assembly. Notice where thisistheattachedartifactsclassifier is specified in the following files.

scripts.xml (Project A):

<assembly>
  <id>thisistheattachedartifactsclassifier</id>
  <formats>
    <format>zip</format>
  </formats>

  <fileSets>
    <fileSet>
      <directory>src/main/resources</directory>
      ...
    </fileSet>
  </fileSets>
</assembly>

pom.xml (Project B):

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-dependency-plugin</artifactId>
  <executions>
    <execution>
      <id>copy-scripts</id>
      <phase>package</phase>
      <goals>
        <goal>copy</goal>
      </goals>
      <configuration>
        <outputDirectory>${basedir}/target/staging</outputDirectory>
        <stripVersion>true</stripVersion>
        <artifactItems>
          <artifactItem>
            <groupId>...</groupId>
            <artifactId>...</artifactId>
            <version>...</version>
            <classifier>thisistheattachedartifactsclassifier</classifier>
            <overWrite>true</overWrite>
            <type>zip</type>
          </artifactItem>
        </artifactItems>
      </configuration>
    </execution>
  </executions>
</plugin>

Solution 1:

Welcome to Stack Overflow :).

You are on the right way. Your real problem is using a zip.

The following configuration is ok and work great for me. It's an old one (2 years ago), and I'm not sure that match the best practices. But I Know that's working.

This allow me to share some resources between projects, especially for unit tests.

Zip Project :

pom.xml

<groupId>com.mycompany</groupId>
<artifactId>cfg_dev</artifactId>
<version>1.1.0</version>

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-assembly-plugin</artifactId>
            <executions>
                <execution>
                    <id>cfg-main-resources</id>
                    <goals>
                        <goal>single</goal>
                    </goals>
                    <phase>package</phase>
                    <configuration>
                        <descriptors>
                            <descriptor>/src/main/assembly/resources.xml</descriptor>
                        </descriptors>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Assembly descriptor : It will produce this artifact : cfg_dev-1.1.0-resources.zip Please, note that

this is a zip archive
the "classifier" is resources (like assembly name)

resources zip false src/main/resources

Main Project :

pom.xml

Please, note that

this depends on a zip archive

the dependency "classifier" is resources (like previous assembly name)

<!-- Unit test dependency -->
<dependency>
    <groupId>com.mycompany</groupId>
    <artifactId>cfg_dev</artifactId>
    <version>${project.version}</version>
    <classifier>resources</classifier>
    <type>zip</type>
    <scope>test</scope>
</dependency>

  ....

<build>
  <testResources>
    <!-- Ressources habituelles  -->
    <testResource>
        <directory>src/test/resources</directory>
        <filtering>true</filtering>
    </testResource>
    <!-- Unzipped resources from cfg_dev  -->
    <testResource>
        <directory>${project.build.directory}/test-resources</directory>
        <filtering>true</filtering>
    </testResource>
</testResources>

<plugins>

    <!-- Unzip shared resources -->
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-dependency-plugin</artifactId>
        <executions>
            <execution>
                <id>unpack-cfg-test-resources</id>
                <goals>
                    <goal>unpack-dependencies</goal>
                </goals>
                <phase>generate-test-resources</phase>
                <configuration>
                    <outputDirectory>${project.build.directory}/test-resources</outputDirectory>
                    <includeArtifactIds>cfg_dev</includeArtifactIds>
                    <includeGroupIds>${project.groupId}</includeGroupIds>
                    <excludeTransitive>true</excludeTransitive>
                    <excludeTypes>pom</excludeTypes>
                    <scope>test</scope>
                </configuration>
            </execution>
        </executions>
    </plugin>
  </plugins>

I hope this is clear and that will help you :)

Solution 2:

An alternate approach could be to give up on zipping entirely, use the standard Maven lifecycle to pack your files as resources in a jar file and access them from your other projects via classpath.

Unless you have specific packing requirements (including, excluding, etc.) this would require no additional configuration: just put your stuff in your project's src/main/resources directory.

This approach has the added benefit of working unchanged when invoked from within an IDE such as Eclipse.

Solution 3:

If you ever want to do something like this from the command line (e.g. from a script without having to write a pom.xml file), here's the way to do it...

You can either specify the individual properties:

mvn dependency:copy -DgroupId=org.apache.maven -DartifactId=maven-core -Dversion=2.2.1 -Dpackaging=zip -Dclassifier=thisistheattachedartifactsclassifier

Or specify them all in one artifact parameter:

mvn dependency:copy -Dartifact=org.apache.maven:maven-core:2.2.1:zip:thisistheattachedartifactsclassifier

With the latter, it is important to keep the classifier at the end, after the packaging/type attribute. Like this: -Dartifact=groupId:artifactId:version:type:classifier

You can also optionally specify the target directory using the -DoutputDirectory=<directory> parameter if required.