Nginx

Rails 5 + Puma + Nginx + ActionCable

In development mode things seemed to take care of themselves. Production mode was a different matter. Let’s just say it was a sensitive and delicate configuration. So in documenting this I’ve tried to condense things to the bare minimum and using the simplest configuration: hosting the “cable” within the host application (i.e. in the same virtual host). For full ActionCable documentation please visit: Rails Guides

Make sure you have a cable.js file (app/assets/javascripts/cable.js)

The “rails new” command should have created this for you.

Create a handler (app/assets/javascripts/channels/chat_channel.coffee)

App.chat = App.cable.subscriptions.create "ChatChannel",
  connected: ->
    alert 'connected'

  disconnected: ->
    alert 'disconnected'

  received: (data) ->
    # do you screen update stuff here

I’ve included popup alerts. These are quite useful when you’re doing this for the first time so you know your basic connection is working.

Make sure you have your channel and connection ActionCable files

Check for app/channels/application_cable/channel.rb and app/channels/application_cable/connection.rb. These should have been created for you. If you’re running ActionCable within your application (rather than on a separate server/vhost) you can add authentication for the connection thus:

module ApplicationCable
  class Connection < ActionCable::Connection::Base
    identified_by :current_user

    def connect
      self.current_user = find_verified_user
    end

    protected
    def find_verified_user
      if current_user = User.find_by(id: cookies.signed[:user_id])
        current_user
      else
        reject_unauthorized_connection
      end
    end
  end
end

Create your own channel file (app/channels/chat_channel.rb)

Here’s where you subscribe to your own broadcast.

class ChatChannel < ApplicationCable::Channel
  def subscribed
    stream_from 'chat_channel'
  end

  def unsubscribed
    # Any cleanup needed when channel is unsubscribed
  end
end

Set your configuration parameters

There are 2 files to change. First we must update config/environments/production.rb and set the config.action_cable constants:

config.action_cable.url = 'ws://myapp.spannersoftware.com/cable' # ws:// is non-secure, wss:// is secure
config.action_cable.allowed_request_origins = [ 'http://myapp.spannersoftware.com' ]

Important: do not add a trailing slash to either of these!

Next update config/cable.yml and set the host and port for the redis server:

development:
  adapter: async

test:
  adapter: async

production:
  adapter: redis
  url: redis://localhost:6379/1

You may not need to change this.

Add the ActionCable metatag

In app/views/layouts/application.html.erb add the following line in the <head> section:

<%= action_cable_meta_tag %>

Install and fire up the Redis server

Redis is a cool bit of kit for providing efficient messaging, for more information go here: Redis.io.

apt-get install redis-server
service redis-server start

Edit /etc/redis/redis.conf to set the port to 6379 and bind to 127.0.0.1.

Configure Nginx and Puma

Here is my Nginx virtual host example:

upstream my_app {
 server unix:/home/myapp/tmp/myapp.sock;
}
server {
 listen 10.10.10.10:80;
 server_name myapp.spannersoftware.com;

 access_log /home/myapp/log/access.log;
 error_log /home/myapp/log/error.log;
 root /home/myapp/public;

 location / {
 try_files /maint.html $uri @ruby;
 }

 location @ruby {
 proxy_pass http://my_app;
 proxy_set_header X-Real-IP $remote_addr;
 proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
 proxy_set_header Host $http_host;
 proxy_redirect off;
 }

 location /cable {
 proxy_pass http://my_app;
 proxy_http_version 1.1;
 proxy_set_header Upgrade $http_upgrade;
 proxy_set_header Connection "upgrade";
 }
}

Here is my Puma config (config/puma.rb):

threads_count = ENV.fetch("RAILS_MAX_THREADS") { 5 }.to_i
threads threads_count, threads_count
bind "unix:/home/myapp/tmp/bluebird2.sock"
environment ENV.fetch("RAILS_ENV") { "production" }
workers ENV.fetch("WEB_CONCURRENCY") { 2 }
daemonize true
pidfile '/home/myapp/tmp/pids/puma.pid'
I'm using a Unix socket here, the default environment is production, the process is daemonized and I've specified a pidfile location. The rest of the settings are default.

Set your app running

Assuming you have the puma gem installed correctly you should be able to run your application complete with working ActionCable.

cd /home/myapp
puma -C config/puma.rb -e production

You should see the message “connected” pop up in your browser when you first load the page. Hopefully you’ve found this helpful but please let me know if I’ve missed anything.