title: Ansible docker_swarm_service with private registry
body: <p>I have an image I wish to use which is hosted in a private docker registry, when deploying the service using the docker cli I would do something like:</p>
  
  <pre><code>docker service  create \
    --with-registry-auth \
    --name my_service \
    registry.example.com/acme/my_image:latest
  </code></pre>
  
  <p>(from docker docs: <a href="https://docs.docker.com/engine/swarm/services/#create-a-service-using-an-image-on-a-private-registry" rel="nofollow noreferrer">create-a-service-using-an-image-on-a-private-registry</a>)</p>
  
  <p>However the <a href="https://docs.ansible.com/ansible/latest/modules/docker_swarm_service_module.html" rel="nofollow noreferrer">docker_swarm_service</a> module in ansible doesn't seem to have any way of supplying <code>--with-registry-auth</code>. This means my services I create aren't scaling to other nodes in the swarm.</p>
  
  <p>I am looking for suggestions on how best to create these services using Ansible with the expectation that the images remain in the private registry and any future nodes added to the swarm can authenticate and download them.</p>