Mapping external usernames to database roles
In some cases, the authentication username is different from the PostgreSQL username. For instance, this can happen when using an external system for authentication, such as certificate authentication (as described in the previous recipe), or any other external or single sign-on (SSO) system authentication method from http://www.postgresql.org/docs/current/static/auth-methods.html (GSSAPI, Security Support Provider Interface (SSPI), Kerberos, Radius, or Privileged Access Management (PAM)). You may just need to enable an externally authenticated user to connect as multiple database users. In such cases, you can specify rules to map the external username to the appropriate database role.
Getting ready
Prepare a list of usernames from the external authentication system and decide which database users they are allowed to connect as—that is, which external users map to which database users.
How to do it…
Create a pg_ident...
