Custom Maven Assembly Descriptors

External

• Custom assembly descriptor reference http://maven.apache.org/components/plugins/maven-assembly-plugin/assembly.html

Internal

• Maven assembly Plugin

Overview

Aside from pre-defined assembly descriptors, Maven allows creation of custom assembly descriptors. Custom assembly descriptors are conventionally placed under src/assembly of the module that executes the plugin.

Assembly Descriptors and System Properties

Maven resolves system properties referred from values specified in the assembly descriptors. This helps with enforcing the pattern where module versions are specified in only one place - the parent project pom.xml. For more details, see "Multi-module maven projects versioning" section.

Example

This is an example of a custom assembly descriptor, used to build a complex release artifact for a multi-module project:

https://github.com/NovaOrdis/events/blob/master/release/src/assembly/release.xml

Elements

<id>

The <id> element in the assembly descriptor specifies the value of the assembly ID. The presence of the <id> element in the assembly descriptor is mandatory, if it is not specified, Maven will generate a parsing error. The assembly ID will become the assembly artifact classifier, present between the version and the extension. For more details on assembly artifact naming rules, see "The Name of the Assembly Artifact" section.

<format>

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

Multiple formats can be provided, and the plugin will generate an archive for each of them.

Archive Base Directory

The plugin is capable of creating an archive with an embedded base directory. This is useful for binaries distributions, to prevent a situation when unziping will "taint" a current directory, by placing unexpected files in it.

<includeBaseDirectory>true</includeBaseDirectory> will trigger the feature. If no <baseDirectory> is explicitly specified, ${project.build.finalName} will be used by default, otherwise the value of the base directory can be customized. <includeBaseDirectory>true</includeBaseDirectory> with no explicit <baseDirectory> is a good default.

File Sets

A <fileSet> allows the inclusion of groups of files into the assembly.

<fileSets>
    <fileSet>
        <directory>${project.build.directory}/bin</directory>
        <outputDirectory>/bin</outputDirectory>
        <includes>
            <include>*.sh</include>
        </includes>
        <fileMode>0755</fileMode>
    </fileSet>
    ...
</fileSets>

Individual Files

<files>
    <file>
        <source>../api/target/events-api-${module.api.version}.jar</source>
        <outputDirectory>lib</outputDirectory>
    </file>
    ...
</files>