title: Unsupported config option for services.db: 'images'
body: <p>I am trying to learn how to utilize docker-compose and was following instructions until I received an error. Here's my docker-compose file.</p>
  
  <pre><code>version: '3.7'
  
  services:
    web:
      build: ./app
      command: python /usr/src/app/manage.py runserver 0.0.0.0:8000
      volumes:
        - ./app/:/usr/src/app/
      ports:
        - 8000:8000
      environment:
        - SECRET_KEY=my_secret_key
        - SQL_ENGINE=django.db.backends.postgresql
        - SQL_DATABASE=postgres
        - SQL_USER=postgres
        - SQL_PASSWORD=postgres
        - SQL_HOST=db
        - SQL_PORT=5432
      depends_on:
        - db
    db:
      images: postgres:10.7-alpine
      volumes:
        - postgres_data:/var/lib/postgresql/data/
  
  volumes:
    postgres_data:
  </code></pre>
  
  <p>When I go back and enter "docker-compose up -d --build", I would get an error saying </p>
  
  <pre><code>ERROR: The Compose file './docker-compose.yml' is invalid because:
  Unsupported config option for services.db: 'images'
  </code></pre>
  
  <p>I think I have the indentation correct and 'images' look okay to me.
  My docker-compose version is 1.23.2 and trying to run this on Mac.
  Any ideas? thanks in advance.</p>