title: How to dynamically change the docker's base image
body: <p>I have two dockerfiles, which are exactly  same with the only difference being the FROM statement. The problem I have is whenever I modify something in one file I have to do the same in another, because they have to be the same.</p>
  <p>One solution for this would be to pass base image as parameter to docker build command. I don't know if that is possible.</p>
  <p>Another would be to have some kind of include files mechanism. In that case I would implement all common steps in a separate file which I would just include in my Dockerfile.</p>