[Generic] Implement refresh_user to periodically refresh OAuth tokens

[jthiltges]

An attempt at OAuth token refresh, following the pattern in PR https://github.com/jupyterhub/oauthenticator/pull/287, without relying on tokens to be JWTs. This should address at least some of issue https://github.com/jupyterhub/oauthenticator/issues/398.

Requirements for token refresh:

• OAuth server response includes expires_in and refresh_token
• State is persisted on hub with c.Authenticator.enable_auth_state = True (to store the refresh_token)

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[kkaraivanov1]

As in the next release of jupyterhub there will be authenticator user group management https://github.com/jupyterhub/jupyterhub/pull/3548 what happens if we have manage_groups=true and the user's group membership changes after auth and before refresh? Your refresh code is not updating user_info['groups'] as it seem.

[jthiltges]

@kkaraivanov1 Thanks for looking at the PR. I agree that group data should be refreshed as well.

Is group membership info already being stored on authentication?

[kkaraivanov1]

The way I understand the intentions behind the PR I mention is if c.Authenticator.manage_groups is set AND if the GenericOAuthenticator adds the groups to user_info['groups'] they will be populated automatically. So to answer your question - it could be Perhaps you can hide that behind a check like if hasattr(self,manage_groups): ........ Please take my thoughts with big grain of salt, I'm not a dev and my python is rudimentary.

[jthiltges]

That makes sense, and thank you for the clarification.

Adding support for user_info['groups'] is probably best addressed in a separate PR. I'll be happy to revise this PR to follow the pattern that the project maintainers prefer.