Easy websocket url configuration

Thanks to feedback from @ascrazy, @jeremy, and @javan

Easy websocket url configuration
Thanks to feedback from @ascrazy, @jeremy, and @javan
62250e38 · Mike Virata-Stone · c362beab · 62250e38 · 62250e38 · 62250e38
5 changed file
--- a/README.md
+++ b/README.md
@@ -330,6 +330,26 @@ ActionCable.server.config.log_tags = [
 ]
 ```

+Your websocket url might change between environments. If you host your production server via https, you will need to use the wss scheme
+for your ActionCable server, but development might remain http and use the ws scheme. You might use localhost in development and your
+domain in production. In any case, to vary the websocket url between environments, add the following configuration to each environment:
+
+```ruby
+config.action_cable.url = "ws://example.com:28080"
+```
+
+Then add the following line to your layout before your JavaScript tag:
+
+```erb
+<%= action_cable_meta_tag %>
+```
+
+And finally, create your consumer like so:
+
+```coffeescript
+App.cable = Cable.createConsumer()
+```
+
 For a full list of all configuration options, see the `ActionCable::Server::Configuration` class.

 Also note that your server must provide at least the same number of database connections as you have workers. The default worker pool is set to 100, so that means you have to make at least that available. You can change that in `config/database.yml` through the `pool` attribute.

--- a/lib/action_cable/engine.rb
+++ b/lib/action_cable/engine.rb
 require 'rails/engine'
 require 'active_support/ordered_options'
+require 'action_cable/helpers/action_cable_helper'

 module ActionCable
  class Engine < ::Rails::Engine
    config.action_cable = ActiveSupport::OrderedOptions.new

+    config.to_prepare do
+      ApplicationController.helper ActionCable::Helpers::ActionCableHelper
+    end
+
    initializer "action_cable.logger" do
      ActiveSupport.on_load(:action_cable) { self.logger ||= ::Rails.logger }
    end

--- a/lib/action_cable/helpers/action_cable_helper.rb
+++ b/lib/action_cable/helpers/action_cable_helper.rb
+module ActionCable
+  module Helpers
+    module ActionCableHelper
+      # Returns an "action-cable-url" meta tag with the value of the url specified in your
+      # configuration. Ensure this is above your javascript tag:
+      #
+      #   <head>
+      #     <%= action_cable_meta_tag %>
+      #     <%= javascript_include_tag 'application', 'data-turbolinks-track' => true %>
+      #   </head>
+      #
+      # This is then used by ActionCable to determine the url of your websocket server.
+      # Your CoffeeScript can then connect to the server without needing to specify the
+      # url directly:
+      #
+      #   #= require cable
+      #   @App = {}
+      #   App.cable = Cable.createConsumer()
+      #
+      # Make sure to specify the correct server location in each of your environments
+      # config file:
+      #
+      #   config.action_cable.url = "ws://example.com:28080"
+      def action_cable_meta_tag
+        tag "meta", name: "action-cable-url", content: Rails.application.config.action_cable.url
+      end
+    end
+  end
+end
--- a/lib/action_cable/server/configuration.rb
+++ b/lib/action_cable/server/configuration.rb
@@ -9,6 +9,7 @@ class Configuration
      attr_accessor :connection_class, :worker_pool_size
      attr_accessor :redis_path, :channels_path
      attr_accessor :disable_request_forgery_protection, :allowed_request_origins
+      attr_accessor :url

      def initialize
        @logger   = Rails.logger

--- a/lib/assets/javascripts/cable.coffee.erb
+++ b/lib/assets/javascripts/cable.coffee.erb
@@ -4,5 +4,9 @@
 @Cable =
  INTERNAL: <%= ActionCable::INTERNAL.to_json %>

-  createConsumer: (url) ->
+  createConsumer: (url = @getConfig("url")) ->
    new Cable.Consumer url
+
+  getConfig: (name) ->
+    element = document.head.querySelector("meta[name='action-cable-#{name}']")
+    element?.getAttribute("content")