Designing a modular authentication server

I'm currently developing - a.k.a have a dirty prototype working of an authentication server.

What it does exactly is to store user data (whatever these are) in a hashtable in a redis DB. It will use some kind of ACL, which I want to be interchangeable (RBAC for example) and finally it will have an interface. It may be an oauth provider, a jwt provider, or a simple basic auth rest interface.

I write this in python, but I think it does not matter.

What I'm thinking of right now is to use an MVC design.

Model changes the user fields Controller changes the middleware (session support etc.) View is actually the authentication interface (rest, normal web, Unix sockets etc)