title: How do I find out why my Docker service is in Pending state?
body: <p>I'm playing <code>Docker Swarm</code>, and using a <code>docker-compose.yml</code> with <code>docker deploy</code>. All services get deployed except for one, which stays in Pending state. I have added a constraint that ties this service to one of the nodes. My question is not so much about this particular problem, but more about how to troubleshoot. The Docker documentation mentions possible causes for a service to be in pending state, but none of those apply (constraint problem, resource drainage).</p>
  
  <p>Can I see the docker swarm 'thought process' somewhere? What is it thinking?</p>
  
  <p>Edit: should have made it more clear that I am using the new, 1.12-introduced, swarm option.</p>