title: link from ngnix installed outside docker to a container
body: <p>friends,
  I have a ubuntu server with ngnix installed outside of docker.</p>
  
  <p>I have a docker image that has a web application, with an ip for example: 172.17.0.3
  (all within the same server)</p>
  
  <p>How can I do it from my nginx to the ip of the name container? for example: "ip container docker"</p>
  
  <p>That structure cannot change, that's how aws service creates it.
  * obs: the Ip can change because of that I need as a dynamic variable.</p>
  
  <pre><code>upstream openerp {
  server "ip container docker":8069;}
  </code></pre>
  
  <p>use: $host or hotname, not work</p>