title: Docker swarm stop grace period doesn't work as expected
body: <p>I am running Docker in swarm mode with several nodes in the cluster.
  According to the documentation written here: <a href="https://docs.docker.com/engine/reference/commandline/service_update/" rel="nofollow noreferrer">https://docs.docker.com/engine/reference/commandline/service_update/</a> and here: <a href="https://docs.docker.com/engine/reference/commandline/service_create/" rel="nofollow noreferrer">https://docs.docker.com/engine/reference/commandline/service_create/</a>, --stop-grace-period command sets the time to wait before force killing a container.</p>
  
  <p><strong>Expected behavior</strong> -
  My expectation was that Docker would wait this period of time until it tries to stop a running container, during a rolling update.</p>
  
  <p><strong>Actual behavior</strong> - 
  Docker sends the termination signal after several seconds the new container with the new version of the image starts.</p>
  
  <p>Steps to reproduce the behavior</p>
  
  <ol>
  <li>docker service create --replicas 1 --stop-grace-period 60s --update-delay 60s --update-monitor 5s --update-order start-first --name nginx nginx:1.15.8</li>
  <li>Wait for the service to start up the container (aprox. 2 minutes)</li>
  <li>docker service update --image nginx:1.15.9 nginx</li>
  <li>docker ps -a
  <a href="https://i.stack.imgur.com/va4Nc.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/va4Nc.png" alt="enter image description here"></a></li>
  <li>As you can see, the new container started and after a second, the
  old one was killed by Docker.</li>
  </ol>
  
  <p>Any idea why?</p>
  
  <p>I also opened an issue on Github, here: <a href="https://github.com/docker/for-linux/issues/615" rel="nofollow noreferrer">https://github.com/docker/for-linux/issues/615</a></p>