Sharing sessions between two flask servers

Question

I have a backend with two flask servers. One that handles all RESTfull request and one that is an flask-socketio server. Is there a way how I can share the session variables (Logged in User etc.) between these two applications? They do run over different ports if that is important.

How I have understood sessions they work over client session cookies so shouldn't both of these servers have access to the information? If yes how? and if not is there a way to achieve the same effect?

Answer 1

There are a couple of ways to go at this, depending on how you have your two servers set up.

The easiest solution is to have both servers appear to the client on the same domain and port. For example, you can have www.example.com/socket.io as the root for your Socket.IO server, and any other URLs on www.example.com going to your HTTP server. To achieve this, you need to use a reverse proxy server, such as nginx. Clients do not connect directly to your servers, instead they connect to nginx on a single port, and nginx is configured to forward requests the the appropriate server depending on the URL.

With the above set up both servers are exposed to the client on the same domain, so session cookies will be sent to both.

If you want to have your servers appear separate to your client, then a good option to share session data is to switch to server-side sessions, stored in Redis, memcache, etc. You can use the Flask-Session to set that up.

Hope this helps!