We now query the external auth provider for the external service's identifier before adding the linking row into the database. This fixes the case where the external service resolves a different identifier for the same username.
Fixes#1477
When the user commits the configuration, if they have chosen a non-DB auth system, we now auto-link the superuser account to that auth system, to ensure they can login again after restart.
This authentication system hits two HTTP endpoints to check and verify the existence of users:
Existance endpoint:
GET http://endpoint/ with Authorization: Basic (username:) =>
Returns 200 if the username/email exists, 4** otherwise
Verification endpoint:
GET http://endpoint/ with Authorization: Basic (username:password) =>
Returns 200 and a signed JWT with the user's username and email address if the username+password validates, 4** otherwise with the body containing an optional error message
The JWT produced by the endpoint must be issued with an issuer matching that configured in the config.yaml, and the audience must be "quay.io/jwtauthn". The JWT is signed using a private key and then validated on the Quay.io side with the associated public key, found as "jwt-authn.cert" in the conf/stack directory.
