com.lukegb.mojo:gitdescribe-maven-plugin 2.0

This plugin is designed to give you a build number. So when you might make 100 builds of version 1.0-SNAPSHOT, you can differentiate between them all. It does this by taking the output of git describe and saving it into a Maven build variable, so you can reference the value in your POM.

<plugin>
    <groupId>com.lukegb.mojo</groupId>
    <artifactId>gitdescribe-maven-plugin</artifactId>
    <version>2.0</version>
</plugin>