In my app, I'm already using the Firebase authentication with Google accounts, but I'd also like to authorize some users who have no Google account. So I'd like to manually add them to the authorized server from the firebase console and to enable the email authentication.
What I don't want is random users to be able to create an account on my app with their email.
Is it possible ? I didn't find a parameter to disable sign in...
I don't think this is possible who can sign in on an individual basis in Firebase Authentication.
Typically sign in to Firebase is either open or closed for everyone. Then you allow them access to specific resources on an individual basis.
For example, you use the Firebase Database or Cloud Firestore you could control access by having a whitelist of approved users in your security rules. See Restrict Firebase users by email
Alternatively, you can set a custom claim on the profiles that you want to grant access, and check that in your security rules: Firebase Authentication with whitelisted email addresses
I'm using passwordless Firebase Authentication and I hacked my way around this by using a callable cloud function that's triggered from my login form. The cloud function looks up the submitted email address in a whitelist firebase node and returns true or false. If true, do sign in. If false, I flash a "we're in closed beta" message.
I add emails to the whitelist node both manually and from a form within a protected admin route in my app.
Firebase Auth doesn't provide official tooling to limit email siginup to specific emails, or allow login but disable signup.
The next best things you could do is
Below is a sample code which limit signup to specific emails https://code.luasoftware.com/tutorials/firebase/setup-firebase-authentication-with-vuejs/
