title: Docker-compose error with service env_file
body: <p>I've been working on passing my sensitive data (credentials) to the docker container through a .env file. I'm using docker-compose and my docker-compose.yml file looks as follows:</p>
  
  <pre><code> services:
     some-service:
       env_file:
         - .env
  </code></pre>
  
  <p>But when I try to do "docker-compose up", I get the below error:</p>
  
  <pre><code> ERROR: In file './docker-compose.yml', service 'env_file' must be a mapping not an array.
  </code></pre>
  
  <p>My .env file has data like</p>
  
  <p>id = 1234567890</p>
  
  <p>pwd = my_pwd</p>
  
  <p>Are there any indentation errors in my file? Any suggestions on how to fix this error?</p>