I maintain a one-time password library that integrates with Ecto.

I haven’t used it with Guardian, so I can’t help you there. As for the workflow, I’m working on a guide to that at the moment - for another library I maintain. I’ll let you know when I get it ready.

Guardian has nodda at all to do with Google style 2fa. Guardian is a way to encode a JWT/Token for cross domain message passing, it is not an authentication thing.

You could do it in Ueberauth pretty easily though, it would fit in a strategy if using a library like what @riverrun has inside it.

I’m interested in implementing 2FA myself. I see it only as an extra step during login, not something to integrate with Guardian to verify on every request. E.g. if the token verification succeeds, then use Guardian to sign-in user. If someone could share a tutorial it will be much appreciated!

From the Guardian repo:

An authentication library for use with Elixir applications.