Rails using Websockets with Nginx and Unicorn?

Question

I am considering implementing chess (which needs websockets) with Rails, and in production deployment using Nginx as a reverse proxy to a bunch of Unicorn processes.

In thinking about how to make that work led me to have the following questions:

As far as I understand websockets are a persistent connection. Since everything goes through the reverse proxy Nginx how exactly would a Unicorn worker process maintain a websocket connection to a client browser? Would Nginx maintain state about which Unicorn process each browser websocket is connected to and act as a kind of intermediary? Does keeping a persistent websocket connection in a Unicorn process block the entire worker process?

Is there a recommended way to implementing chess (with websockets) using Rails?

Answer 1

Connecting synchronous processing by Unicorn with asynchronous delivery using nginx would imply some logic on nginx side that seems at least awkward to me. At most - impossible.

There is a Railscast about Private Pub gem that makes use of Thin webserver. It's way more suitable for this task: it's asynchronous, it's able to handle many concurrent requests with event-based IO. So I suggest you replace Unicorn with Thin or install Thin side-by-side.

Puma webserver might also be an option, however, I can't give more info about that.

Answer 2

nginx won't do websockets. Are you sure you can't do this with AJAX? If you really need push capability you could try something built around the Comet approach: http://en.wikipedia.org/wiki/Comet_(programming)

Faye is a pretty good gem for implementing comet in rails: http://faye.jcoglan.com/