Looks like I need to write first reply myself though I really hope others with experience will follow.
I was told that all the buzzwords are in my post. But my comment on this would be, not all of us are building yet another Blog site.

In relation to what I already wrote above, about what @josevalim wrote a while back, I really want to share first of such blog posts that I was able to find. Thanks to @iacobson a blog about joining Phx_gen_auth with Oauth. If there are more like this, please share them here.

Hey,

another one!

Phx.gen.Auth + JWT

Regards,
Tomaz

Hi,

I have implemented a RBAC based authentication and authorization service in Elixir and it’s used in production in our company.

I would suggest that if the use-case is a real production use and your requirements allow it, use existing solutions like Keycloak. Their authorization overview guide.

At least authorization for websockets works with Keycloak when using Nginx (Example). I don’t know if Liveview works too.

If it’s not possible to use existing solutions and since you are already using microservices(?) then I would suggest going for option 2. I’m not familiar with libraries in this area but I can say that authentication is easy, authorization can be easy but with RBAC, it usually gets complicated.

If you have only few services and aren’t using API gateway/reverse proxy solution, then you need to handle parsing request data in each service and making validation request to the authentication&authorization service. This means that you can use whatever means of communication between services (backend and frontend) but there’s more work for each service.

If you are using API gateway/reverse proxy solution like Nginx, then services can just make requests to each other without worrying (too much) about authentication and authorization since the gateway will handle it. Of course you need to implement necessary code in the gateway. This varies for each solution.

As for those OAuth, stateless, stateful, and other buzzwords, I would suggest that you evaluate your requirements and try to keep everything as simple as possible. OAuth + OpenID is complex and if you don’t have clear use-cases for it, then I wouldn’t choose it.

There’s not much difference between stateful and stateless authentication. If your requirements mandate that you must be able to easily revoke authentication, then I would suggest going for stateful authentication.

Basic flow with stateful authentication:

1. User logins to system
2. Save all required information (at least user_id, session_key) in database
3. Set user_id into httponly cookie which can be signed/encrypted
4. SPA knows that login was a success the request returns 200
5. The browser adds the cookie to each following request from the SPA to backend
6. The authentication and authorization service checks that cookie is in the request, it’s valid, and the information is valid.

I was able to successfully integrate Phx_gen_auth and Ueberauth, using the referenced @iacobson blog post, using the Google strategy in a new project.