Release Plugin

The release plugin allows you to perform software releases it follows a series of steps to perform a release of your current project. The release plugin saves a lot of repetitive, manual work, releasing a project is made in two steps: prepare and perform.

Release Process Overview

The release plugin basically releases versions of you project, for example the process would be as follows

version 1.0.0-SNAPSHOT - the current version of your project
version 1.0.0 - when you perform a release this will be the version
version 1.0.1-SNAPSHOT - all the POMs will then needs to be updated to the next development release

Trying to perform the above manually (a lot of repeative tasks) would be very error prone, tis is where the release plugin comes into play. The two steps are below

Prepare Release	Perform Release
Check no uncommitted changes Check no snapshots Update release version Run tests Tag in SCM Next snapshot version Commit	Checkout of SCM with SCM tag Run release goals (default deploy site deploy) Remove release files Checkout SCM master

If there are any problems a release rollback (release:rollback)might be needed

will revert POM's back to the pre-release state
SCM tag may be removed (you might have to remove it manually)
rollback will not work if release:clean has been run

release:clean will perform the following

cleans up release files (removes release.properties and any backed up POM's

SCM Plugin Setup

The Source Control Management plugin can be used to work with the companies SCM solution (example Github or GitLab), it fully suports a number of of SCM versions (for example Git, CVS, Subversion, etc).

To configure the SCM we need to perform the following, you will also need to setup the SCM in the settings.xml file

Define the SCM in the SCM section of the POM
define the URL in the connection property
the developerConnection element defines the write URL
the URL is prefixed with scm:[scm-provider]:[SCM URL]
the tag element defines the tag project is under
the url element defines the public repository URL

First we add a propery called project.scm.id that points to the settimgs.xml git setup (see below), then we add the scm element (right-hand screenshot), all three pieces allows you to connect to github for source control management.

The settings.xml github setup

Release Plugin Setup

To setup the release plugin in the POM file we need to add an additional plugin as per below

Release Prepare, Perform and Rollback

Now that Maven is setup we can start to run the commands to prepare and perform a release

prepare

mvn clean release:prepare

Note: Maven will ask you for the release (select default) and the snapshot (select default), 
two files will be created a backup of the POM and a release.properties file.

prepare (dryrun)

mvn release:prepare -DdryRun=true

Note: dryRun will will put not change anything but ive us the output, good for checking before you run for real.

perform

mvn release:perform

Note: This will also deploy (Packagecloud or Nexus for example)

After the perform the POM version will be updated

If you need to rollback a release (cannot do if you have run release:clean)

rollback

mvn release:rollback

Note: this will remove the backup POM, remove the release.properties file and rollback the <version>, 
however it won't update github this has to be done manually.