Automatic per-variant google_services.json configurations with Gradle

build.gradle

//append code below to existing build.gradle

def appModuleRootFolder = '.'
def srcDir = 'src'
def googleServicesJson = 'google-services.json'

task switchToDebug(type: Copy) {
    def buildType = 'debug'
    description = 'Switches to DEBUG google-services.json'
    from "${srcDir}/${buildType}"
    include "$googleServicesJson"
    into "$appModuleRootFolder"
}

task switchToRelease(type: Copy) {
    def buildType = 'release'
    description = 'Switches to RELEASE google-services.json'
    from "${srcDir}/${buildType}/"
    include "$googleServicesJson"
    into "$appModuleRootFolder"
}

afterEvaluate {
    processDebugGoogleServices.dependsOn switchToDebug
    processReleaseGoogleServices.dependsOn switchToRelease
}