Deploying to track based on Git Branch

build.gradle

// Deployment
play {
    track = getDeploymentTrack()
    serviceAccountCredentials = file(System.getenv("PRIVATE_KEY") ?: "deployment_private_key.json")
    defaultToAppBundles = true
    resolutionStrategy = "ignore"
}

// The deployment track is based on the branch.
static def getDeploymentTrack() {
    def branch = gitBranch()
    def track = 'internal'
    if (branch.equals("master")) {
        track = "beta"
    } else if (branch.equals("release")) {
        track = "alpha"
    }
    println("DEPLOYMENT TRACK: " + track)
    return track
}

static def gitBranch() {
    def branch = ""
    def proc = "git rev-parse --abbrev-ref HEAD".execute()
    proc.in.eachLine { line -> branch = line }
    proc.err.eachLine { line -> println line }
    proc.waitFor()
    println("BRANCH: " + branch)
    branch
}