major.minor plugin for Jenkins

~~Recently, I’ve been tasked with setting up a build environment at work and we decided to go with Hudson and now Jenkins. I think the best part of Jenkins is its extensibility in the form of writing plugins to make it do exactly what you want. So my first plugin was to change the build numbers that Jenkins uses like #1, #2 etc. to something more meaningful for our scenario and so was born the major.minor plugin.

The premise of the plugin is quite simple. In our projects, we would like to see build names of the form major.minor.revision. We use subversion for source code management and so the revision number here refers to the svn revision number. The major and the minor numbers are configured when the build is initially setup and are initialized to 1 and 00 respectively. So, the first build name might be something like 1.00.23 if the svn revision at that point happened to be 23.

At some point down the line in the project cycle, we might like to increment the minor or major number and this can be done manually after a build by using already Jenkins feature to edit the build name. Since the plugin picks up the major and minor part of the build name from the previous build of the project, subsequent builds will now have the correct major and minor sections.

Now that the build name has been changed, when you browse through the builds directory for your project, it will be hard for you to figure out which build is what because Jenkins only creates directories using the build number like #2, #3 etc. and the date/time when the build was executed. To make it easier, the plugin also creates a new symbolic link with the build name in the builds directory. Now the Jenkins UI and builds directory matches and its easier for you to get to the right build.

When you enable this plugin, you get a new configuration section for your project. In this section, you will configure a regex to match build names against. I’ve made it a regex so that it is a little bit more flexible and can be still be used even if your organization does not use a major.minor.revision format for naming builds. The important thing is that you add a capturing group in your build name regex which is used to insert the new revision number into the build name. Note that if you don’t use svn for scm, the plugin still works and inserts the build number in place of the revision number. The other configuration is for setting the initial build name for your project like 1.00.00.

The plugin also makes available a BUILD_NAME environment variable for any scripts that might need it.

Hope this plugin helps anyone looking for nicer build names and thanks to the Jenkins project for a great build tool.

The plugin source is available on Github and you are free to fork and tinker with it suit your needs.