Automatic versioning of Android build using git describe with Gradle

Put the following in your build.gradle file for the project. There’s no need to modify the manifest directly: Google provided the necessary hooks into their configuration.

def getVersionCode = { ->
    try {
        def code = new ByteArrayOutputStream()
        exec {
            commandLine 'git', 'tag', '--list'
            standardOutput = code
        }
        return code.toString().split("\n").size()
    }
    catch (ignored) {
        return -1;
    }
}

def getVersionName = { ->
    try {
        def stdout = new ByteArrayOutputStream()
        exec {
            commandLine 'git', 'describe', '--tags', '--dirty'
            standardOutput = stdout
        }
        return stdout.toString().trim()
    }
    catch (ignored) {
        return null;
    }
}
android {
    defaultConfig {
        versionCode getVersionCode()
        versionName getVersionName()
    }
}

Note that if git is not installed on the machine, or there is some other error getting the version name/code, it will default to what is in your android manifest.