Feature request: dynamic username support for credential rotation

Greetings!

I have noticed that the password option can be set to a function, allowing for a seamless way to reconnect when credentials are rotated. In my current workflow, we also rotate usernames. For example, we use user_1 and user_2, but only one of them is allowed to log in at a given time (let's say it's user_1).

When we need to rotate credentials, we generate a random password for user_2 and enable it for login. We then update the secrets with username = user_2 and the new password, notifying applications of the credential change. After a brief grace period, user_1 is disabled until the next rotation.

My issue is that while the password can be dynamically set, the username cannot. Is there a workaround for this, or could support for a dynamic username option be implemented? This feature would greatly enhance the flexibility and security of our credential management process.

Thank you for considering this request.

Start by locating the existing handling for the password option and how reconnects obtain credentials. Determine how a dynamic username should be evaluated during credential rotation, then verify that reconnects use the updated username and password without breaking static username behavior.