[Flutter/dart] Use google_sign_in in 2 firebase projects（Android）

Overview

If you're using firebase, you want to separate your development environment from your production environment.

In this process in Flutter, I stumbled on Android's google_sign_in

Detail

Create two firebase projects, one for development and one for production, and start them in debug mode. Then, I get the following error in google_sign_in.

Unhandled Exception: PlatformException(sign_in_failed, com.google.android.gms.common.api.ApiException: 10: , null, null)

This is because in google_sing_in (in firebase?) the combination of the application id (like com. ***) and the SHA1 fingerprint cannot be duplicated.

(See here for details. However, the error did not go away even with the measures described here.）

Solution

As a workaround, change the application id when in debug mode.

Write as follows in /android/app/build.gradle.

defaultConfig {
    applicationId "com.xxx.yyy"
    ・・・
}
buildTypes {
    debug {
        applicationIdSuffix ".debug"
    }
    ・・・    
}

Also, modify /android/app/src/debug/google-service.json as follows.

"client": [
  {
    "client_info": {
      ・・・
      "android_client_info": {
        "package_name": "com.xxx.yyy.debug"
      }
    },

Without this modification, you get the following error.

Execution failed for task ':app:processDebugGoogleServices'.

> No matching client found for package name 'com.xxx.yyy

After taking the above measures, I was able to sign in with google safely.