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The Multi Module Maven Release Plugin for Git

This plugin is an alternative to the maven-release-plugin which was created with the following principles:

  • It should be trivial to release modules from a multi-module plugin, and only those modules that have changes should be released
  • No commits should be made to a repo during a release
  • Maven conventions such as developing against SNAPSHOT versions should be retained
  • Git should not need to be installed on the system.

See the introductory blog post for more background.

The plugin works with the idea that a software module has two types of versions: the “business version” and the “build number”. The business version is used for semantic versioning, and may be something like “1.0”, “1.1.0”, etc. During development, the version in the pom is the business version with -SNAPSHOT appended. During a release, module version becomes business-version.build-number and this is what the repo is tagged with, and this is what the pom version becomes in the deployed artifact (however this version is not committed as a change to your pom).

This plugin automatically generates build numbers, starting from 0 and incrementing each time, by looking at previous releases in the Git history. Alternatively, you can use a number that increments on each release - like your CI server’s build number for example.

Quickstart

Add the following to your plugins section:

<plugin>
    <groupId>com.github.danielflower.mavenplugins</groupId>
    <artifactId>multi-module-maven-release-plugin</artifactId>
    <version>3.0.0</version>
</plugin>

Release your project by running mvn releaser:release

See usage for more details.

Differences with the maven-release-plugin

  • Only Git is supported
  • Each module released will have a separate tag with its artifact ID and version so that it is easy to see when a version of a module was released
  • A module is only released if there are changes to it
  • The release version of the pom is not committed back to the repository
  • Tests are run once by default (or optionally not at all)

Prerequisites

The plugin requires Maven 3.0.1 or later and Java 8 or later. If you need Java 6 support, then use version 1.4.6. If you need Java 7 support, then use version 2.1.3.