title: Using variables in config file
body: <p>I have this dockerfile that is working correctly.</p>
  
  <p><a href="https://github.com/shantanuo/docker/blob/master/packetbeat-docker/Dockerfile" rel="nofollow noreferrer">https://github.com/shantanuo/docker/blob/master/packetbeat-docker/Dockerfile</a></p>
  
  <p>The only problem is that when my host changes, I need to modify packetbeat.yml file </p>
  
  <pre><code>  hosts: ["https://944fe807b7525eaf163f502e08a412c5.us-east-1.aws.found.io:9243"]
    password: "rzmYYJUdHVaglRejr8XqjIX7"
  </code></pre>
  
  <p>Is there any way to simplify this change? Can I use environment variable to replace these 2 values?</p>