Firebase SDK multiple projects in one apk

Question

I am trying to initialize the FirebaseApp, only by using the FirebaseOptions builder, like this(I use only applicationId and ApiKey, since I only want the analytics for start):

FirebaseOptions options = new FirebaseOptions.Builder()
.setApplicationId(applicationID) // Required for Analytics.
.setApiKey(apiKey) // Required for Auth.
.build();
FirebaseApp.initializeApp(context, options);

I do not have a google-services.json file in my project, I have removed the FirebaseInitProvider, like this, in my AndroidManifest.xml:

<provider android:name="com.google.firebase.provider.FirebaseInitProvider"
   android:authorities="${applicationId}.firebaseinitprovider"
   android:exported="false"
   tools:node="remove"/>

I would like to have the application id sent from my server, since I want more than one projects, and I don't really care if I lose some event during the initialization of the app. When starting the application, while trying to View events in the Android Studio debug log, like this:

adb shell setprop log.tag.FA VERBOSE

adb shell setprop log.tag.FA-SVC VERBOSE

adb logcat -v time -s FA FA-SVC

I get: Missing google_app_id. Firebase Analytics disabled.

I do not want to use google_app_id in a strings.xml static file since I want more than one projects. However I tried having all the app ids in an XML file and trying to change them using reflection before the FirebaseApp.initializeApp, but that doesn't seem to work.

Answer 1

the default FirebaseApp initialization looks alike this (this is being used when passing no name):

FirebaseApp fb = FirebaseApp.initializeApp(context, options, "[DEFAULT]");

The FirebaseOptions values used by the default app instance are read from string resources.

but ...one can instead assign custom names, in order not to read from string resources:

FirebaseApp fb01 = FirebaseApp.initializeApp(context, options, "primary");
FirebaseDatabase db01 = FirebaseDatabase.getInstance(fb01);

FirebaseApp fb02 = FirebaseApp.initializeApp(context, options, "secondary");
FirebaseDatabase db02 = FirebaseDatabase.getInstance(fb02);

found this Firebase Blog, which is the credible source requested.

also the documentation for FirebaseApp generally explains it.