title: docker compose volumes not contains files
body: <p>Before adding the volumes command, the container build and run normally. I can see the files are installed in the container's <code>/var/www/html</code>.</p>
  
  <p>But, I want to make custom code and so want to mount a local folder to <code>/var/www/html</code>. </p>
  
  <p>However, when I bring up the container (docker-compose up), no files are copied to my local folder.</p>
  
  <p><strong>docker-compose.yml</strong></p>
  
  <pre><code>web:
      image: wordpress
      links:
       - mysql
      environment:
       - WORDPRESS_DB_PASSWORD=rootpass
      ports:
       - "80:80"
      working_dir: /var/www/html
      volumes:
       - ./html:/var/www/html
  mysql:
      image: mysql:5.7
      environment:
       - MYSQL_ROOT_PASSWORD=rootpass
       - MYSQL_DATABASE=wordpress
  </code></pre>