title: docker compose override a ports property instead of merging it
body: <p>My docker compose configs look like this:</p>
  <p>docker-compose.yml</p>
  <pre class="lang-yaml prettyprint-override"><code>version: '3.5'
  
  services:
      nginx:
          ports:
              - 8080:8080
  </code></pre>
  <p>docker-compose.prod.yml</p>
  <pre class="lang-yaml prettyprint-override"><code>version: '3.5'
  
  services:
      nginx:
          ports:
              - 80:80
  </code></pre>
  <p>Now, when I run command: <code>docker-compose -f docker-compose.yml -f docker-compose.prod.yml up</code> the nginx exposes on host machine two ports: <code>8000</code> and <code>80</code>, because it merges ports properties:</p>
  <pre class="lang-yaml prettyprint-override"><code>version: '3.5'
  
  services:
      nginx:
          ports:
              - 8080:8080
              - 80:80
  </code></pre>
  <p>Is there a way to override it? I want to expose only port <code>80</code>.</p>