title: How to use environment variables in supervisord commands
body: <p>How can I use an environment variable in a supervisord command?
  I tried:</p>
  
  <p><code>flower --broker=$MYVAR</code></p>
  
  <p>but it doesn't work (variable is not expanded), so I tried using an inline python script:</p>
  
  <pre><code>command=python -c "import os;os.system('flower --broker={0}'.format(os.environ['MYVAR']))"
  </code></pre>
  
  <p>The command above works, but then I'm unable to terminate the process using <code>supervisorctl stop</code> ...I get "stopped" back but the process is actually still running!
  How can I solve my issue? (I don't want to put that parameter inline)</p>