We want to copy some documents, namely a releasenote.txt, into a doc directory inside the zip file that our build creates. I’m using the assembly plugin to create the zip file, and the assembly descriptor specifies the release note file to copy and filter

The tokens I’ve got in the release notes are:

• @version@
• @currentdate@
• @build.number@

And I have defined the values in the pom:

<currentdate>${maven.build.timestamp}</currentdate>

<build.number>${p4.revision}</build.number>

<version>5.0.0</version>

Now, if I copy the release note using the maven resource plugin, which by default copies resources to the classes output directory, the filtering works fine. This is how I defined it in the pom:

<resources>
<resource>
<directory>src/main/resources</directory>
<filtering>true</filtering>
<includes>
<include>RELEASENOTE.txt</include>
</includes>
</resource>
</resources>

Unfortunately I don’t want to copy it to the classes directory, I want it to go in the zip assembly, in a docs directory, hence the definition in the assembly descriptor (called kit.xml). The full kit.xml can be seen at the end of this post. So, the suggested thing to do is specify the file you want to copy, and set <filtered> to true, like this:

<file>
<source>src/main/resources/RELEASENOTE.txt</source>
<outputDirectory>doc</outputDirectory>
<filtered>true</filtered>
</file>

Of course, it doesn’t work. And here’s why – unlike the maven resource plugin, the assembly plugin’s filtering doesn’t seem to work with tokens in the @bla@ format, but instead insists on using ${bla} instead. And not only that, but it won’t read my properties and values that I’ve defined in my pom either, it requires you to create a filter.properties file which defines variables/values in the style:

variable1=value1

variable2=-value2

Obviously I don’t want to do that, I’ve already got them defined in my pom and I hate duplication (think DRY principle!). So that left me with 2 options. I could explicitly define the maven resource plugin, like this:

<plugin>
        <artifactId>maven-resources-plugin</artifactId>
        <version>2.5</version>
        <executions>
          <execution>
            <id>copy-resources</id>
            <phase>prepare-package</phase>
            <goals>
              <goal>copy-resources</goal>
            </goals>
            <configuration>
              <outputDirectory>some/other/dir</outputDirectory>
              <resources>
                <resource>
                  <directory>src/main/resources</directory>
                  <filtering>true</filtering>
                </resource>
              </resources>
            </configuration>
          </execution>
        </executions>
      </plugin>

and tell it to copy my releasenote.txt file to some directory, and do the filtering on it in the process, and then bind it to a phase which happens before my assembly plugin is called (as shown above). I would then need to change my assembly descriptor to tell it where to find the new, properly filtered releasenote.txt file and copy it to the doc dir, like this:

<file>
<source>src/main/resources/RELEASENOTE.txt</source>
<outputDirectory>doc</outputDirectory>
<filtered>true</filtered>
</file>

An alternative, and this is the one I went for, is to let the maven resource filtering copy the file from src/main/resources into the target/classes directory as it does by default, and then tell the assembly descriptor to copy it from there to the doc directory:

<file>
<source>src/main/resources/RELEASENOTE.txt</source>
<outputDirectory>doc</outputDirectory>
</file>

It’s far from ideal and it’s very annoying that the maven assembly plugin does filtering differently, but in the end it gets the job done.

My full assembly descriptor, kit.xml:

<assembly>
<id>kit</id>
<formats>
<format>zip</format>
</formats>
<fileSets>
<fileSet>
<directory>src/main/resources</directory>
<outputDirectory>doc</outputDirectory>
<includes>
<include>*.*</include>
</includes>
<excludes>
<exclude>latest.properties</exclude>
<exclude>RELEASENOTE.txt</exclude>
</excludes>
</fileSet>
</fileSets>
<files>
<file>
<source>target/classes/RELEASENOTE.txt</source>
<outputDirectory>doc</outputDirectory>
<filtered>true</filtered>
</file>
<file>
<source>target/${artifactId}-${version}.${packaging}</source>
<outputDirectory>/</outputDirectory>
<destName>container-filtering-module.jar</destName>
</file>
</files>
</assembly>