As I was working with a team on a project using Git, I decided to somehow automate labeling builds like projectname-1.0.3.516. With SVN this is easily achieved as each revision has its ordinal number, but in Git a revision is instead indentified by a SHA hash, and branching is used commonly and extensively, which further complicates things. So I searched around on StackOverflow and composed the following workflow:

• Any "milestone" version changes (i.e. first 2 or 3 numbers) are set manually via tags on branch master.
• Each commit on the current branch subsequent to the last tag on master adds to the build number. Lightweight tags are ignored.
• If building from a separate branch, its name should be included in the version.

Example:
On master, the last tag is named v1.0 and 3 commits have been made since that tag. You are working on a branch feature (beginning from the last commit in master) and have made 2 commits to it. Full version number for your build becomes feature-1.0.5. If you switch back to master, full version number will become 1.0.3.

This is partially achieved by command git describe. But as I am usually working on a Java project in Eclipse, I want an Ant build script; from Ant I can call custom java code, but the current version of JGit doesn't support describe. I also find it comfortable to manage the repository via Eclipse's egit, so I don't need to actually install Git and, on Windows, have it in my PATH environment variable, which means that I can't call <exec executable="git"/> from the Ant script.

Having considered all that, I created this custom Ant task.

Download the jar from the Releases page or build it from source, include it along with JGit and gitective in your project (the jars with licenses can be found in this repo's lib folder). Example of your Ant target:

<taskdef name="jgitversion" classname="hunternif.jgitversion.JGitVersionTask">
    <classpath>
        <pathelement path="path/to/jgitversion.jar"/>
        <pathelement path="path/to/gitective.jar"/>
        <pathelement path="path/to/jgit.jar"/>
    </classpath>
</taskdef>

<target name="build-release">
    <jgitversion dir="." property="build.version"/>
    <echo message="${build.version}" />
    ...
</target>

The dir property must be set to point to the root of your local git repository clone. The property property is the name of the property into which the calculated version name will be written.