title: Ansible variable in key/value key
body: <p>I'm passing env variables to a Docker container in an ansible playbook, how do I set an Ansible variable in the key in the key/value of an env?</p>
  
  <p>So this:</p>
  
  <pre><code>- name: webproxy container
    docker_container:
      name: "webproxy"
      image: "webproxy"
      env:
        SERVICE_443_NAME: "webproxy"
  </code></pre>
  
  <p>becomes this:</p>
  
  <pre><code>- name: webproxy container
    docker_container:
      name: "webproxy"
      image: "webproxy"
      env:
        SERVICE_{{ port_number }}_NAME: "webproxy"
  </code></pre>