title: node app instance name when running via pm2 cluster
body: <p>I have backend node app, that is run by pm2 in cluster mode.
  I'm running fixed 2 instances.</p>
  
  <p>Is there a way to identify instance name or number from within executed app?</p>
  
  <p>App name is "test", I would like to get from within the app "test 1" and "test 2" for given instance.</p>
  
  <p>Thanks!</p>