Prepare your project to use the maven-release-plugin

To be able to make a solid start with the maven-release-plugin, there are 2 things you should include in our pom:

• the scm-section with a developerConnection
• the maven-release-plugin with a locked version

The developerConnection contains the URL of the Source Control Management system pointing to the folder containing this pom.xml This URL is prefixed with scm:[scm-provider] so the plugin can pick the right implementation for committing and tagging. The Maven SCM-page contains an overview all the supported SCMs, per SCM you can see how the URL should look like.

<project>
  ...
  <scm>
    <developerConnection>scm:svn:https://svn.mycompany.com/repos/myapplication/trunk/mycomponent/</developerConnection>
  </scm>
  
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-release-plugin</artifactId>
        <version>2.5.3</version>
      </plugin>
    </plugins>
    ...
  </build>
  ...
</project>

The following are some common scenarios in preparing a release.

Use a different username in the SCM server than the one in the operating system

Most of the SCMs are simply executed as an external command as the current user on your system. If this username is not the same as the SCM username, you may need to set the following option:

mvn -Dusername=your_scm_username release:prepare

Set where to tag the files in Subversion

This example shows how to set the repository location for all tags to be created in Subversion. Note that this is not needed if you use the standard SVN layout, where the root project is in trunk, and there is a sibling tags directory.

<project>
  ...
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-release-plugin</artifactId>
        <version>2.5.3</version>
        <configuration>
          <tagBase>https://svn.mycompany.com/repos/myapplication/releases</tagBase>
        </configuration>
      </plugin>
    </plugins>
    ...
  </build>
  ...
</project>

Do a Dry Run

Since the Release Plugin performs a number of operations that change the project, it may be wise to do a dry run before a big release or on a new project. To do this, commit all of your files as if you were about to run a full release and run:

mvn release:prepare -DdryRun=true

This will ask all the same questions, run the same tests, and output a copy of how the POMs will look after transformation. You can check the output and review the POMs, then run:

mvn release:clean

This will remove all of the files created above, and the project will be ready to execute the proper release.

Run in Batch Mode

Sometimes it is desirable to do the commit/tag process on a regular interval (e.g. to produce nightly or integration builds through a build server). To use the default inputs for the versions and tag information and not prompt for any values, use Maven's --batch-mode setting:

mvn --batch-mode release:prepare

Use a staging repository

Sometimes it is desirable to deploy a pre-release to be approved before made publicly available. One option is to create release candidates versions using the release:perform goal, but the final deployed artifact will NOT be the exact one that has been approved as RCx.

A common solution is to use a staging repository, where a test-version is deployed with it's documentation for review. If all is fine, it is then copied to the public repository. Using this strategy, the artifact that has been tested IS the one that is deployed.

The release:stage goal uses this strategy. It replaces the release:perform goal and does the same tasks, but requires a stagingRepository parameter. It will automatically re-configure the deploy and site-deploy goals to use the staging strategy.

After the release is complete, the release.properties and other release files will NOT be removed, so that you can still execute a release:rollback if some error has been detected and a new candidate must be created after some fixes. You just need to use a distinct tag in SCM, or rename the one that has been created if the SCM provider supports renaming tags.