title: docker-compose ports not exposed as expected
body: <p>I'm developing a Magento site using a <a href="https://devdocs.magento.com/guides/v2.3/cloud/docker/docker-development.html" rel="nofollow noreferrer">Docker local environment</a>.</p>
  
  <p>I've installed the <a href="https://github.com/SnowdogApps/magento2-theme-blank-sass" rel="nofollow noreferrer">Sass blank theme</a> and <a href="https://github.com/SnowdogApps/magento2-frontools" rel="nofollow noreferrer">frontools</a>. Now I'm trying to get <a href="https://www.browsersync.io/" rel="nofollow noreferrer">browsersync</a> working.</p>
  
  <p>I'm doing this inside the <code>cli</code> image, because that's where I initially setup gulp prior to trying my hand at browsersync.</p>
  
  <p>Here are the respective configs</p>
  
  <p>docker-compose.yml</p>
  
  <pre><code>cli:
    image: 'magento/magento-cloud-docker-php:7.1-cli-scss2'
    ports:
      - '3001:3001'
    depends_on:
      - db
      - redis
      - elasticsearch
      - rabbitmq
    volumes:
      - '~/.cache/composer:/root/.composer/cache'
      - '.:/var/www/magento:rw'
    volumes_from:
      - appdata
    env_file:
      - ./docker/global.env
      - ./docker/config.env
  </code></pre>
  
  <p>gulpfile.js</p>
  
  <pre><code>gulp.task('serve', ['sass'], function() {
  
      browserSync.init({
          proxy: 'hz.moxune.net',
          port: 3001,
          open: false,
          notify: false,
      });
  
      gulp.watch([
          '../../../app/design/frontend/Magento/my-theme/styles/**/*.*.scss',
          ['sass']
      ]);
  });
  </code></pre>
  
  <p>It seems to be working on the host machine, which is to say if I run <code>lynx http://cli-container-ip:3001</code>, the site loads. However it is not exposed over the network (the server is on my LAN, not my local machine). So despite having</p>
  
  <pre><code>ports:
      - '3001:3001'
  </code></pre>
  
  <p>after starting up the stack with <code>docker-compose up</code>, running <code>docker ps</code> reveals the PORTS section of the listing is empty...</p>
  
  <pre><code>CONTAINER ID        IMAGE                                            COMMAND                  CREATED             STATUS              PORTS                                      NAMES
  93b73452fb18        magento/magento-cloud-docker-php:7.1-cli-scss2   "/docker-entrypoint.…"   3 seconds ago       Up 2 seconds                                                   magento_cli_run_63
  </code></pre>
  
  <p>Seems I'm not doing something right with the <code>ports</code> specification?</p>