Authentication

When a client connection is established Supavisor needs to verify the credentials of the connection.

Credential verificiation is done either via user records or an auth_query.

Tenant User Record

If no auth_query exists on the tenant record credentials will be looked up from a user and verified against the client connection string credentials.

There must be one or more user records for a tenant where is_manager is false.

Authentication Query

If the user in the client connection is not found for a tenant it will use the user where is_manager is true and the auth_query on the tenant to return matching credentials from the tenant database.

A simple auth_query can be:

SELECT rolname, rolpassword FROM pg_authid WHERE rolname=$1

Alternatively, create a function to return a username and password for a user:

CREATE USER supavisor;

REVOKE ALL PRIVILEGES ON SCHEMA public FROM supavisor;

CREATE SCHEMA supavisor AUTHORIZATION supavisor;

CREATE OR REPLACE FUNCTION supavisor.get_auth(p_usename TEXT)
RETURNS TABLE(username TEXT, password TEXT) AS
$$
BEGIN
    RAISE WARNING 'Supavisor auth request: %', p_usename;

    RETURN QUERY
    SELECT usename::TEXT, passwd::TEXT FROM pg_catalog.pg_shadow
    WHERE usename = p_usename;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

REVOKE ALL ON FUNCTION supavisor.get_auth(p_usename TEXT) FROM PUBLIC;
GRANT EXECUTE ON FUNCTION supavisor.get_auth(p_usename TEXT) TO supavisor;

Update the auth_query on the tenant and it will use this query to match against client connection credentials.

SELECT * FROM supavisor.get_auth($1)