29 Aug 2015 By: Greg Molnar

ActionCable is a new framework for real-time communication over websockets and it will be part of Rails 5. I am not going to get into too much detail about it, you can read the very detailed readme of the project on this link: ActionCable.

The websockets server is running in a separate process from the main Rails application which means you need to authenticate your users there too. In the example app, David used a simple cookie based authentication in the app itself and re-validated the cookie at the websocket connection. This is good for demonstration, but many of the Rails based apps are using Devise for authentication so I want to share, how I solved the authentication with Devise.

The websocket server doesn't have a session, but it can read the same cookies as the main app, so I figured, I will just set a cookie with the user id and verify that at the socket connection. To do this, I used a Warden hook:

# app/config/initializers/warden_hooks.rb Warden :: Manager . after_set_user do | user , auth , opts | scope = opts [ :scope ] auth . cookies . signed [ " #{ scope } .id" ] = user . id end

# app/channels/application_cable/connection.rb module ApplicationCable class Connection < ActionCable :: Connection :: Base identified_by :current_user def connect self . current_user = find_verified_user logger . add_tags 'ActionCable' , current_user . name end protected def find_verified_user if verified_user = User . find_by ( id : cookies . signed [ 'user.id' ] ) verified_user else reject_unauthorized_connection end end end end

This is nice and simple, but I needed some sort of a timeout to expire the session, so I set an expiry time too in the cookies:

# app/config/initializers/warden_hooks.rb Warden :: Manager . after_set_user do | user , auth , opts | scope = opts [ :scope ] auth . cookies . signed [ " #{ scope } .id" ] = user . id auth . cookies . signed [ " #{ scope } .expires_at" ] = 30 . minutes . from_now end

# app/channels/application_cable/connection.rb . . . protected def find_verified_user verified_user = User . find_by ( id : cookies . signed [ 'user.id' ] ) if verified_user && cookies . signed [ 'user.expires_at' ] > Time . now verified_user else reject_unauthorized_connection end end . . . .

One thing left, is to invalidate the cookie on sign out, which can be done in another Warden hook:

# app/config/initializers/warden_hooks.rb . . . Warden :: Manager . before_logout do | user , auth , opts | scope = opts [ :scope ] auth . cookies . signed [ " #{ scope } .id" ] = nil auth . cookies . signed [ " #{ scope } .expires_at" ] = nil end . . .

That's it, now I can share the Devise authentication with my websocket server. If you want to see this in an example, you can check my fork of the actioncable-example.