title: Starting rails server as deamon doesn't trigger worker cluster
body: <p>I want to start the rails server in production mode as a deamon running a worker cluster. When I start my rails program everything works as expected.</p>
  
  <pre><code>rails s -e production -b 0.0.0.0
  =&gt; Booting Puma
  =&gt; Rails 5.0.0.1 application starting in production on http://0.0.0.0:3000
  =&gt; Run `rails server -h` for more startup options
  [12340] Puma starting in cluster mode...
  [12340] * Version 3.4.0 (ruby 2.3.0-p0), codename: Owl Bowl Brawl
  [12340] * Min threads: 5, max threads: 5
  [12340] * Environment: production
  [12340] * Process workers: 3
  [12340] * Preloading application
  [12340] * Listening on tcp://0.0.0.0:3000
  [12340] Use Ctrl-C to stop
  [12340] - Worker 0 (pid: 12347) booted, phase: 0
  [12340] - Worker 1 (pid: 12349) booted, phase: 0
  [12340] - Worker 2 (pid: 12353) booted, phase: 0
  </code></pre>
  
  <p>however when I add the -d rails starts in single mode, confirmed by checking running processes</p>
  
  <pre><code>rails s -e production -b 0.0.0.0 -d
  =&gt; Booting Puma
  =&gt; Rails 5.0.0.1 application starting in production on http://0.0.0.0:3000
  =&gt; Run `rails server -h` for more startup options
  </code></pre>
  
  <p>checking running processes confirms only one instance is running, not the clustered mode expected.</p>
  
  <p>So, how do I correctly launch with workers as a deamon process?</p>
  
  <p>Any help is much appreciated.</p>
  
  <p>NOTE: I am also running puma_worker_killer for rolling restarts in case that helps.</p>
  
  <p>rails (5.0.0.1)
  puma (3.4.0)
  puma_worker_killer (0.1.0)</p>