Flask-socketio Sticky Sessions

[aktoak]

i want to clarify something about the use of sticky session.
i'd be glad if you can tell me if these statements are correct

one worker:

1. if i only use 1 worker i don't need stick sessions at all.

multiple works:

1. if i used flask-socketio with manage_session=True, and because flask-socketio uses memory to store client session then i do need stick sessions.
2. if i used flask-socketio with manage_session=False, and use Flask-Sessions with redis for example to manage client sessions
   but allow http polling for websockets connections then i still need sticky sessions for http polling.
3. if i used flask-socketio with manage_session=False, and use Flask-Sessions with redis for example to manage client sessions
   and permit only websocket connections (without long polling) then i also don't need sticky session?

[miguelgrinberg]

No, you have some things wrong. You seem to be confusing user sessions with sticky sessions and these are completely different things. The user session, is where you store client specific data. The sticky sessions are a configuration setting for your load balancer. I would rewrite your analysis as follows:

1. If you have one worker, then you don't need a load balancer, so speaking about sticky sessions in this context makes no sense.
2. If you have multiple workers, then your load balancer needs to be configured with sticky sessions in the normal case.
3. (Exception to 2) If your clients connect directly with the WebSocket protocol (instead of doing the normal connection with long-polling and then upgrading to WebSocket), then sticky sessionsi n the load balancer aren't necessary and can be omitted. Not using sticky sessions in the load balancer basically breaks long-polling.