Authenticate Using Google Play Games Services on Android

You can use Google Play Games services to sign players in to an Android game built on Firebase. To use Google Play Games services sign-in with Firebase, first sign the player in with Google Play Games, and request an OAuth 2.0 auth code when you do so. Then, pass the auth code to PlayGamesAuthProvider to generate a Firebase credential, which you can use to authenticate with Firebase.

Before you begin

Set up your Android project

  1. If you haven't already, add Firebase to your Android project.

  2. In your module (app-level) Gradle file (usually <project>/<app-module>/build.gradle.kts or <project>/<app-module>/build.gradle), add the dependency for the Firebase Authentication library for Android. We recommend using the Firebase Android BoM to control library versioning.

    Also, as part of setting up Firebase Authentication, you need to add the Google Play services SDK to your app.

    dependencies {
    // Import the BoM for the Firebase platform
    implementation(platform("com.google.firebase:firebase-bom:33.7.0"))

    // Add the dependency for the Firebase Authentication library
    // When using the BoM, you don't specify versions in Firebase library dependencies
    implementation("com.google.firebase:firebase-auth")
    
    // Also add the dependency for the Google Play services library and specify its version
    implementation("com.google.android.gms:play-services-auth:21.3.0")    
}

    By using the Firebase Android BoM, your app will always use compatible versions of Firebase Android libraries.

    (Alternative)  Add Firebase library dependencies without using the BoM

    If you choose not to use the Firebase BoM, you must specify each Firebase library version in its dependency line.

    Note that if you use multiple Firebase libraries in your app, we strongly recommend using the BoM to manage library versions, which ensures that all versions are compatible. 

    dependencies {
    // Add the dependency for the Firebase Authentication library
    // When NOT using the BoM, you must specify versions in Firebase library dependencies
    implementation("com.google.firebase:firebase-auth:23.1.0")
    
    // Also add the dependency for the Google Play services library and specify its version
    implementation("com.google.android.gms:play-services-auth:21.3.0")    
}
         Looking for a Kotlin-specific library module? Starting in October 2023 (Firebase BoM 32.5.0), both Kotlin and Java developers can depend on the main library module (for details, see the FAQ about this initiative).

Set up your Firebase project

  1. Set your game's SHA-1 fingerprint from the Settings page of the Firebase console.

    You can get the SHA hash of your signing certificate with the gradle signingReport command: 

    ./gradlew signingReport

  2. Enable Google Play Games as a sign-in provider:

    1. Find your project's web server client ID and client secret. The web server client ID identifies your Firebase project to the Google Play auth servers.

      To find these values:

      1. Open your Firebase project in the Google APIs console credentials page.
      2. In the OAuth 2.0 client IDs section, open the Web client (auto created by Google Service) details page. This page lists your web server client ID and secret.

    2. Then, in the Firebase console, open the Authentication section.

    3. On the Sign in method tab, enable the Play Games sign-in provider. You will need to specify your project's web server client ID and client secret, which you got from the APIs console.

Configure Play Games services with your Firebase app information

  1. In the Google Play Console, open your Google Play app or create one.

  2. In the Grow section, click Play Games services > Setup & Management > Configuration.

  3. Click Yes, my game already uses Google APIs, select your Firebase project from the list, and then click Use.

  4. On the Play Games services configuration page, click Add Credential.

    1. Select the Game server type.
    2. In the OAuth client field, select your project's web client ID. Be sure this is the same client ID you specified when you enabled Play Games sign-in.
    3. Save your changes.

  5. Still on the Play Games services configuration page, click Add Credential again.

    1. Select the Android type.
    2. In the OAuth client field, select your project's Android client ID. (If you don't see your Android client ID, be sure you set your game's SHA-1 fingerprint in the Firebase console.)
    3. Save your changes.

  6. On the Testers page, add the email addresses of any users who need to be able to sign in to your game before you release it on the Play Store.

Integrate Play Games sign-in into your game

First, integrate Play Games sign-in into your app. See Sign in to Android Games for complete instructions.

In your integration, when you build the GoogleSignInOptions object, use the DEFAULT_GAMES_SIGN_IN configuration and call requestServerAuthCode:

Kotlin

val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_GAMES_SIGN_IN)
    .requestServerAuthCode(getString(R.string.default_web_client_id))
    .build()
MainActivity.kt

Java

GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_GAMES_SIGN_IN)
        .requestServerAuthCode(getString(R.string.default_web_client_id))
        .build();
MainActivity.java

You must pass your web server client ID to the requestServerAuthCode method. This is the ID that you provided when you enabled Play Games sign-in in the Firebase console.

Authenticate with Firebase

After you add Play Games sign-in to your app, you need to set up Firebase to use the Google account credentials that you get when a player signs in successfully with Play Games.

  1. First, in your sign-in activity's onCreate method, get the shared instance of the FirebaseAuth object:

Kotlin

private lateinit var auth: FirebaseAuth
// ...
// Initialize Firebase Auth
auth = Firebase.auth
GoogleSignInActivity.kt

Java

private FirebaseAuth mAuth;
// ...
// Initialize Firebase Auth
mAuth = FirebaseAuth.getInstance();
GoogleSignInActivity.java
  1. When initializing your Activity, check to see if the player is already signed in with Firebase:

Kotlin

override fun onStart() {
    super.onStart()
    // Check if user is signed in (non-null) and update UI accordingly.
    val currentUser = auth.currentUser
    updateUI(currentUser)
}
GoogleSignInActivity.kt

Java

@Override
public void onStart() {
    super.onStart();
    // Check if user is signed in (non-null) and update UI accordingly.
    FirebaseUser currentUser = mAuth.getCurrentUser();
    updateUI(currentUser);
}
GoogleSignInActivity.java
 
If the player isn't signed in, present the player with your game's
signed-out experience, including the option to sign in.
  1. After a player signs in with Play Games either silently or interactively, get the auth code from the GoogleSignInAccount object, exchange it for a Firebase credential, and authenticate with Firebase using the Firebase credential:

Kotlin

// Call this both in the silent sign-in task's OnCompleteListener and in the
// Activity's onActivityResult handler.
private fun firebaseAuthWithPlayGames(acct: GoogleSignInAccount) {
    Log.d(TAG, "firebaseAuthWithPlayGames:" + acct.id!!)

    val auth = Firebase.auth
    val credential = PlayGamesAuthProvider.getCredential(acct.serverAuthCode!!)
    auth.signInWithCredential(credential)
        .addOnCompleteListener(this) { task ->
            if (task.isSuccessful) {
                // Sign in success, update UI with the signed-in user's information
                Log.d(TAG, "signInWithCredential:success")
                val user = auth.currentUser
                updateUI(user)
            } else {
                // If sign in fails, display a message to the user.
                Log.w(TAG, "signInWithCredential:failure", task.exception)
                Toast.makeText(
                    baseContext,
                    "Authentication failed.",
                    Toast.LENGTH_SHORT,
                ).show()
                updateUI(null)
            }

            // ...
        }
}
MainActivity.kt

Java

// Call this both in the silent sign-in task's OnCompleteListener and in the
// Activity's onActivityResult handler.
private void firebaseAuthWithPlayGames(GoogleSignInAccount acct) {
    Log.d(TAG, "firebaseAuthWithPlayGames:" + acct.getId());

    final FirebaseAuth auth = FirebaseAuth.getInstance();
    AuthCredential credential = PlayGamesAuthProvider.getCredential(acct.getServerAuthCode());
    auth.signInWithCredential(credential)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (task.isSuccessful()) {
                        // Sign in success, update UI with the signed-in user's information
                        Log.d(TAG, "signInWithCredential:success");
                        FirebaseUser user = auth.getCurrentUser();
                        updateUI(user);
                    } else {
                        // If sign in fails, display a message to the user.
                        Log.w(TAG, "signInWithCredential:failure", task.getException());
                        Toast.makeText(MainActivity.this, "Authentication failed.",
                                Toast.LENGTH_SHORT).show();
                        updateUI(null);
                    }

                    // ...
                }
            });
}
MainActivity.java

If the call to signInWithCredential succeeds you can use the getCurrentUser method to get the user's account data.

Next steps

After a user signs in for the first time, a new user account is created and linked to their Play Games ID. This new account is stored as part of your Firebase project, and can be used to identify a user across every app in your project.

In your game, you can get the user's Firebase UID from the FirebaseUser object:

Kotlin

val user = auth.currentUser
user?.let {
    val playerName = it.displayName

    // The user's Id, unique to the Firebase project.
    // Do NOT use this value to authenticate with your backend server, if you
    // have one; use FirebaseUser.getIdToken() instead.
    val uid = it.uid
}

MainActivity.kt

Java

FirebaseUser user = mAuth.getCurrentUser();
String playerName = user.getDisplayName();

// The user's Id, unique to the Firebase project.
// Do NOT use this value to authenticate with your backend server, if you
// have one; use FirebaseUser.getIdToken() instead.
String uid = user.getUid();
MainActivity.java

In your Firebase Realtime Database and Cloud Storage Security Rules, you can get the signed-in user's unique user ID from the auth variable, and use it to control what data a user can access.

To get a user's Play Games player information or to access Play Games services, use the APIs provided by the Google Play Games SDK.

To sign out a user, call FirebaseAuth.signOut():

Kotlin

Firebase.auth.signOut()
MainActivity.kt

Java

FirebaseAuth.getInstance().signOut();
MainActivity.java