title: Using multi-line value in .env file in docker-compose
body: <p>I have an installer which pumps out some values to a .env file to be used by docker-compose. All of this has worked so far with the exception of an SSH key which cannot be seemingly used.</p>
  
  <p>I have so far tried with both the correctly formatted private key and also replacing new lines with <code>\n</code>. However, this breaks the work flow further down the line and does not appear using printenv within the container as a multi line variable which is required.</p>
  
  <p>docker-compose.yml</p>
  
  <pre><code>myservice:
    build: .
    environment:
      - SSH_KEY
      - SINGLE_LINE_VALUE
  </code></pre>
  
  <p>.env (ignore the obviously broke sshkey)</p>
  
  <pre><code>SINGLE_LINE_VALUE=I Load just fine
  SSH_KEY="---------------
  ABCDEFGH
  --------------------
  "
  </code></pre>
  
  <p>by the time the container is running, the environment value for SSH_KEY is simply "---------------</p>
  
  <p>Any ideas very much appreciated.</p>