Remove email fallback

[Ithanil]

Don't fall back to email as identifier if no user with external_id found.

For more details see https://github.com/bigbluebutton/greenlight/issues/5872

On top of this change, I introduced the following mechanism for our setup, to allow users to log in if they received an email that was previously owned by a different external account (which has previously logged into Greenlight). Without this code, Greenlight will not create the new user due to conflicting email addresses.

    # Replace any existing email with "dummy" value
    email_user = User.find_by(email: user_info[:email], provider:)
    if email_user.present? && user_info[:external_id].present? && email_user.external_id != user_info[:external_id]
      email_user.update(email: "#{email_user.id}@example.net")
    end

This changes the email associated with that other account to a dummy value, which does not cause issues and will be updated on the next login. The only alternative would be to completely delete the other account in Greenlight.

@farhatahmad Let me know if you want this code in GL, maybe behind a config flag.

[FSeifer]

Hello @Ithanil

May I ask why this email fallback was removed?

This change broke our BBB-Setup, since we have an IDP configured for with pre-existing users and rely on this mechanism to set the external_id of a user that has not yet logged in via our IDP.

With this change, instead of a successful login, we get a generic error message and a support ticket...

Regards FSeifer

[Ithanil]

Hello @Ithanil

May I ask why this email fallback was removed?

This change broke our BBB-Setup, since we have an IDP configured for with pre-existing users and rely on this mechanism to set the external_id of a user that has not yet logged in via our IDP.

With this change, instead of a successful login, we get a generic error message and a support ticket...

Regards FSeifer

I'm sorry that the change broke your setup, that's why I proposed to use a config flag for this behavior. Regarding the rationale, see the corresponding issue that was linked above: https://github.com/bigbluebutton/greenlight/issues/5872