title: ERROR: The Compose file '.\docker-compose.yml' is invalid because: Unsupported config option for services.drupal: 'postgres'
body: <p>Here is my <strong>docker-compose.yml</strong>:</p>
  <pre><code>version: &quot;3&quot;
  
  services:
      drupal:
          image: drupal
          ports:
          - &quot;8080:80&quot;
          volumes:
          - drupal-modules:/var/www/html/modules
          - drupal-profiles:/var/www/html/profiles
          - drupal-sites:/var/www/html/sites
          - drupal-themes:/var/www/html/themes
          postgres:
              image: postgres
              environment:
                  - POSTGRES_PASSWORD=mypasswd
  
  volumes:
      drupal-modules:
      drupal-profiles:
      drupal-sites:
      drupal-themes:
  </code></pre>
  <p>As I run</p>
  <pre><code>$ docker-compose up
  </code></pre>
  <p>I get:</p>
  <pre><code>ERROR: The Compose file '.\docker-compose.yml' is invalid because:
  Unsupported config option for services.drupal: 'postgres'
  </code></pre>
  <p>what's the problem?</p>