title: How to control docker-compose build order?
body: <p>I have three services to build, A、B and C. A should be built in the very first place, because B and C depend on A (they import A as image). I thought they should be built in order but I just find out they are built in some random order?</p>
  
  <p>So, how do I control build order in <code>docker-compose.yml</code>?</p>