title: how do you manage secret values with docker-compose v3.1?
body: <p>Version 3.1 of the docker-compose.yml specification introduces support for <a href="https://docs.docker.com/engine/reference/commandline/secret/" rel="noreferrer">secrets</a>. </p>
  
  <p>I tried this: </p>
  
  <pre><code>version: '3.1'
  
  services:
    a: 
      image: tutum/hello-world
    secret: 
      password: the_password
    b:
      image: tutum/hello-world
  </code></pre>
  
  <p><code>$ docker-compose up</code> returns:</p>
  
  <p><code>Unsupported config option for services.secret: 'password'</code></p>
  
  <p>How can we use the secrets feature in practice?</p>