Firebase Auth (OTP) -> Supabase Auth

[Yehuda-Edelstein]

I have a Firebase app that allows for OTP phone verification and I would like to use it with my Supabase project -- Supabase offers 4 different SMS providers, but I don't understand why Firebase Auth wouldn't also work. Perhaps I'm not understanding, but a user signs up or signs in using their phone number (via Firebase) and if they are verified, a uid from Firebase is returned; can't we use this in the users table and follow Supabase's normal session logic? What specifically is different about Firebase phone OTP?

[GaryAustin1]

You can't use Supabase Auth with another complete Auth system. The users in auth.users have to be created with Supabase Auth.

There is an option though for third party Auth: https://supabase.com/docs/guides/auth/third-party/overview
And for Firebase: https://supabase.com/docs/guides/auth/third-party/firebase-auth

These don't allow you to use the session handling from Supabase Auth, but do allow you to access the Supabase resources with your JWT from those providers.

[Yehuda-Edelstein]

Again, I'm not sure I understand, but why can't we create a user when a Firebase user is created (via phone) return the firebase_id and then create a Supabase user with that as a separate column -- once the user is verified, whether new or returning, their firebase_id will always match, let's say, with their user_id? I guess I'm not understanding why once it's verified via Firebase, we can't tell Supabase this is a new/returning user, check the ids and give them a session?

[GaryAustin1]

You seem to want to use a UUID in place of one generated by Supabase Auth. That is currently not possible if the user is signed in or generated with Supabase Auth. And there is no way to generate a Supabase Auth session (different from providing a JWT in the authorization header) from a 3rd party Auth system. You could certainly create a Supabase user and add another UUID in app metadata or in a table to link it to the Supabase created user. You can't add another column to the Supabase users table, but you can use app metadata.