WebSockets with Passenger 5.0.30

[Arindam Mukherjee]

Sorry to be posting again with the same problems because some of my earlier questions went unanswered, likely because they weren't detailed enough.

I am trying to support a WebSocket interface to my Rails application. I am on Rails 4 with no plans of moving to Rails 5 immediately. I use Phusion Passenger 5.0.30 behind nginx.

I want to use em-websocket (+eventmachine) to build this support. What are Passenger configuration settings that I must use?

    server {

      listen 80 default_server;

      server_name ergo;

      root /home/user/www/testapp/public;

      passenger_enabled on;

      passenger_app_env development;

    

      passenger_max_preloader_idle_time 0;

    

      location /notify {

        proxy_pass http://ergo:3004/notify;

        proxy_http_version 1.1;

        proxy_set_header Upgrade $http_upgrade;

        proxy_set_header Connection "upgrade";

        proxy_set_header Host $host;

        passenger_force_max_concurrent_requests_per_process 0;

      }

    }

Using the above configuration, and the following code for start the EM loop in `config/initializers/event_machine_init.rb`, I cannot get the websocket server to work. Are there additional config changes needed?

    require 'eventmachine'

    require 'em-websocket'

    

    module EventMachineInit

      def self.start

        if defined?(PhusionPassenger)

          PhusionPassenger.on_event(:starting_worker_process) do |forked|

          # for passenger, we need to avoid orphaned threads

            if forked && EM.reactor_running?

              EM.stop

            end

    

            Thread.new do

              puts "Starting EventMachine thread"

              EM.run do

                EM::WebSocket.run(host: "0.0.0.0", port: 3004) do |ws|

                  ws.onopen do |handshake|

                    puts "WebSocket connection open"

                    ws.send "Hello Client, you connected to #{handshake.path}"

                  end

    

                  ws.onclose { puts "WebSocket connection closed" }

    

                  ws.onmessage do |msg|

                    puts "Received message: #{msg}"

                    ws.send "Pong: #{msg}"

                  end

                end

              end

            end

            die_gracefully_on_signal

          end

        end

      end

    

      def self.die_gracefully_on_signal

        Signal.trap("INT")  { EM.stop }

        Signal.trap("TERM") { EM.stop }

      end

    end