title: Docker-Compose Environment-Variables blank string
body: <p>I'm trying to get the Env-Variables in Docker-Compose to work. My Files:</p>
  <p>env/test.env:</p>
  <pre><code>XUSER=you
  XHOME=/home/${XUSER}
  </code></pre>
  <p>docker-compose.yml:</p>
  <pre><code>version: '3'
      services:
       abc:
          build: .
          image: xyz:latest
          container_name: xyz
          env_file:
            - env/test.env
          user: &quot;${XUSER}&quot;
  </code></pre>
  <p>docker-compose up --build</p>
  <p>docker-compose config</p>
  <pre><code>WARNING: The XUSER variable is not set. Defaulting to a blank string.
      services:
        kernel:
          build:
            context: xyz
          container_name: xyz
          environment:
            XHOME: /home/you
            XUSER: you
          image: xyz:latest
          user: ''
  </code></pre>
  <p>As you can see user: '' is an empty string, but the env_file works. I found some old Bug reports about this issue, I'm not sure I doing something wrong or not.</p>