Maven Release Plugin

This post describes the installation and usage of the Maven Release Plugin. The plugin uses behind the scene a GIT repository configured in the SCM (Source Code Management) section of the POM (Project Object Model).

In your project's main pom.xml, add the following plugin inside you build / pluginManagement / plugins node.

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-release-plugin</artifactId>
    <version>2.5.3</version>
    <configuration>
        <goals>deploy</goals>
        <autoVersionSubmodules>true</autoVersionSubmodules>
    </configuration>
    <dependencies>
        <dependency>
            <groupId>org.apache.maven.scm</groupId>
            <artifactId>maven-scm-api</artifactId>
            <version>1.8.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.maven.scm</groupId>
            <artifactId>maven-scm-provider-gitexe</artifactId>
            <version>1.8.1</version>
        </dependency>
    </dependencies>
</plugin>

Although there is no explicit reference to the Maven SCM plugin, the Release plugin makes use of the SCM API and GIT provider packages.

Further in the pom.xml, we define the GIT repository to use:

<scm>
    <developerConnection>scm:git:https://server/your-repository.git</developerConnection>
    <tag>HEAD</tag>
</scm>

If distribution of binaries is enabled (e.g. using Artifactory), you can configure this under node distributionManagement in your pom.xml:

<distributionManagement>
    <snapshotRepository>
        <id>my-artifactory</id>
        <url>http://my-server/snapshot</url>
    </snapshotRepository>
    <repository>
        <id>my-artifactory</id>
        <url>http://my-server/release</url>
    </repository>
</distributionManagement>

Configure the credentials for repository in your ~/.m2/settings.xml file:

<server>
    <id>my-artifactory</id>
    <username>my-user</username>
    <password>UNENCRYPTED_PASSWORD</password>
</server>

Using the Maven Release Plugin

1. Make sure that:
a) all your stuff is checked in. Releases cannot be performed if any file not checked in/committed;
b) you have Java 1.8 and your JAVA_HOME points to it;

2. Go to command line (either PC or Mac… the commands are the same)

3. Go to the project you want to release (to root folder that contains the main pom.xml).
E.g.:
/Projects/rootFolder

4. Run command
mvn release:prepare

There will be tons of stuff going on, but this is an interactive process. You can select the release name, new SCM code name, next version development name, etc. AFAIK, all the defaults are fine. So don’t mess with this unless there is some good reason (such as you want to change the release name because something happened and a name is already taken)

5A. If command at #4 executed successfully, run command:
mvn release:perform

This will do the actual release, check-in stuff, upload bunch of deliverables to artifactory, etc.
If this step is successful, you’re done. No need for anything else. Check SourceTree (browse GIT) and marvel at your new release.
Note that currently the release is done in GIT under the name of the current user. This can be changed and be performed by some service account (but that is not the case for now). So the user running this command has to be able to check-out/check-in stuff in GIT.

5B. If command at #4 or #5A failed, run command:
mvn release:rollback

This will delete a bunch of temporary files and put the old version back in the POMs. You should run rollback before correcting any errors thrown during the release. Only after running ‘rollback’, proceed to change, fix and checkin/commit stuff.

6. Optional - run command:
mvn release:clean

This deletes a bunch of temporary directories used during the release/deploy phases. Not mandatory.