Websockets

[jotaen]

• Basic setup in frontend and backend
  • Setup websockets for groups #65
  • Unsubscribe
• Fix websocket connection in production
  • Currently, it can’t connect in production. (The rest of the app is not affected, though.)
  • Cleanup configuration
• Authentication
  • Make sure that only authenticated users have access to subscriptions.
  • Check authentication on socket connect #69
• Upgrade backend to Apollo server v3
  • We are still on Apollo server v2. The migration shouldn’t be wildly complicated, but we need to account for a few structural changes in the APIs and dependencies. This is an internal refactoring, the usage of subscriptions stays the same as before.
  • Upgrade backend to Apollo Server v3 #68
• Check and decide for connectivity settings, e.g. the reconnect behaviour.
  • We should do that after the Apollo server v3 upgrade, to avoid doing redundant work
  • Automatically reconnect to websocket #70
• Use Redis as PubSub transport (optional; re-discuss)
  • Currently, we use the in-memory PubSub mechanism from Apollo. That’s not recommended for production, though. We could choose ignore that, because we have a single-server setup at the moment. On the other hand it doesn’t seem complicated to setup right away, mostly because we already have a Redis cache up and running (for sessions).

[jotaen]

@HildoBijl The websockets are all set up now in production, per 1d2e7d8.

The problem was the nginx proxy config, which required additional headers for the connection upgrade (from HTTPS to websocket).