Overview

Google Sign-In allows players to log in with their Google account. This is similar to Platform: Google Play Games login, except is cross-platform, is less geared towards games and is more generic.

Setup

To use Google Sign-In, you need to:

1. Configure a Google API Console project.

   Follow instructions at https://developers.google.com/identity/sign-in/android/start-integrating.

   INFO

   Note: These are the same steps as with the 1. Create a Project in Google Play Console section of Platform: Google Play Games, so if you've done those before, no need to do it again!

2. Configure the game server to accept and validate Google Sign-In requests.

   In the relevant Options.<env>.yaml, set:

   GooglePlayStore:
     EnableGoogleAuthentication: true
     GooglePlayOAuth2ClientCredentialsPath: [Oauth 2.0 client credentials json created in step 1]

3. Implement the client-side logic.

   In the game UI, allow players to log in and log out. After a successful login, send a SocialAuthenticationClaimGoogleSignIn request.

Example Client Integration

In this example, we use the Google Sign-In plugin from https://github.com/googlesamples/google-signin-unity.

1. Configure the plugin once:

   GoogleSignIn.Configuration = new GoogleSignInConfiguration()
   {
       RequestIdToken = true,
       WebClientId = <Oauth 2.0 client id created in step 1>
   };

   Note that rather than hard-coding the WebClientId, client may also use MetaplaySDK.Connection.ServerOptions.GameServerGooglePlaySignInOAuthClientId after connection has been established.

2. On app launch, start opportunistic silent sign-in:

   GoogleSignIn.DefaultInstance.SignInSilently().ContinueWith(task =>
   {
       if (task.Status == TaskStatus.RanToCompletion)
       {
           OnGALoggedIn(task.Result);
       }
       else if (task.IsFaulted)
       {
           // Silent sign-in failed, do nothing but observe the exception
           _ = task.Exception;
       }
   });

3. On user UI action, perform new login and logout:

   // On sign-in button tapped: Perform log-in flow.
   // \note: Make sure to manually Sign-Out first to force new login flow and the
   //        generation of a new token.
   GoogleSignIn.DefaultInstance.SignOut();
   GoogleSignIn.DefaultInstance.SignIn().ContinueWith(task =>
   {
       if (task.Status == TaskStatus.RanToCompletion)
       {
           // login success
           OnGALoggedIn(task.Result);
       }
       else if (task.IsFaulted)
       {
           // Login failed
           _ = task.Exception;
       }
   });

   // On log-out button tapped: Sign out.
   GoogleSignIn.DefaultInstance.SignOut();
   OnGALoggedOut();

   DANGER

   Race Condition Warning: Task completions are not guaranteed to be executed on the Unity thread. Proper synchronization is required.

4. Handle passing the pending login state to the game server:

   void OnLoggedIn(GoogleSignInUser user)
   {
       string claimedId = user.UserId;
       string idToken = user.IdToken;
       var claim = new SocialAuthenticationClaimGoogleSignIn(claimedUserId, idToken)
       MetaplaySDK.MessageDispatcher.SendMessage(new SocialAuthenticateRequest(claim))
   }