Firebase Google Login on Android

Introduction

This guide will help you integrate Google Sign-In with Firebase Authentication on Android. I assume you have already completed the general Firebase Google setup

Note

I will assume that you have not yet created your Android app in the Firebase Console. If you have, your steps will be slightly different.

Setup Steps

1. Go to your project overview over at console.cloud.google.com

   

2. Click on the Add app button

   

   Note

   It is possible that you will have to look here for this button. This applies only if you have already created a different app in the Firebase Console.

   

3. Select Android

   

4. Fill the first part of the form

   1. Fill the Android package name
      1. Open Android Studio at your app using npx cap open android
      2. At the very bottom of the navigator, find the Gradle Scripts
      3. Find build.gradle for the module app
      4. Copy the android.defaultConfig.applicationId. This will be your package name in the Firebase console

      Note

      The ID shown here will differ from the one I will use for the rest of the guide. I will use app.capgo.plugin.SocialLogin for the rest of the guide.

      5. Paste it in the Firebase console
   2. Click on the Register app button

5. Skip the Download and then add config file step

   

6. Skip the Add firebase SDK step

   

7. Click on the Continue to console button

   

8. If you do not get automatically authenticated, go to settings -> general -> your apps -> find your android app and click on it

   

9. Get your SHA1 fingerprint

   Follow steps 10-11 from the Google Login Android setup guide:

   1. Now, open the terminal. Make sure that you are in the android folder of your app and run ./gradlew signInReport

      

   2. Scroll to the top of this command. You should see the following. Copy the SHA1.

      

   Note

   I will use a slightly different SHA1 for the rest of the guide, because I have changed computes since writing the original Google login android setup guide.

   Caution

   The SHA1 is very important to get right. If you mess up, the authentication will fail in strange ways. Please READ THE GOOGLE LOGIN ANDROID SETUP GUIDE to get it right.

10. Add the SHA1 to the Firebase project

    1. Click on the Add fingerprint button
    2. Paste the SHA1 you copied in the previous step
    3. Click on the Save button

11. Get your web client ID

    1. Go to Build -> Authentication
    2. Click on the Sign-in method button
    3. Click on the Google provider
    4. Click on the Web SDK configuration button
    5. Copy the Web client ID. This will be your webClientId in the initialize method of the plugin.
    

12. Use the web client ID in JS.

    Note

    I recommend using the authenticateWithGoogle helper function available in the authUtils.ts file of the example app.

At this point, you are TECHNICALLY ready to use Google Sign-In with Firebase Authentication on Android. However, I would recommend double-checking the setup in the Google Cloud console as explained in the next step.

Double-check the setup in Google Cloud console

In order to make sure that the setup is correct, you should double-check the setup in the Google Cloud console.

1. Go to console.cloud.google.com

2. Find your project

   1. Click on the project selector
   2. Search up your project by the exact name of your Firebase project and click on it. In my case, it is sociallogin-tutorial-app.

3. Open the search bar and open credentials

   1. Open the search bar
   2. Search for credentials and click on the APIs and Services one (number 2 on the screenshot)

4. Verify that you see both the Android and Web client IDs in the list.

   

   Caution

   If you do not see both the Android and Web client IDs in the list, you have made a mistake in the setup. Please go back and check your steps.

   It is also possible, and it has happened to me, that you already have added the Android SHA1 hash with the same app ID in a different project. This will result in Firbase being unable to create an Android client ID. In this case, you will need to remove the SHA1 from the other project as well as on Firebase (using the Firebase console to remove the android app) and recreate it on Firbase

5. Verify that the Android client ID is correctly configured in the Firebase console.

   1. Click on the Android app
   2. Confirm that the SHA1 hash is correctly configured and that it matches the one you copied in the previous steps.

6. Verify that the Web client ID is correctly configured in the Firebase console.

   1. Click on the Web app
   2. Confirm that the client ID matches the one you copied in the previous steps.

   Note

   Please ignore the rest of the settings of the web client. We will discuss this on the web setup guide.

Voila! You are now ready to use Google Sign-In with Firebase Authentication on Android.

Troubleshooting

If authentication hangs or fails:

• Verify the idToken audience matches your Firebase web client ID
• Check that Google Sign-In is enabled in Firebase Console
• Ensure the SHA-1 fingerprint is correctly configured
• Review the example app code for reference