title: Docker-compose doesn't resolve DNS to correct service
body: <p>I have two services, <code>web</code> and <code>helloworld</code>. The following is my docker-compose YAML file:</p>
  
  <pre><code>version: "3"
  
  services:
    helloworld:
      build: ./hello
      volumes:
        - ./hello:/usr/src/app
      ports:
        - 5001:80
    web:
      build: ./web
      volumes:
        - ./web:/usr/share/nginx/html
      ports:
        - 5000:80
      depends_on:
        - helloworld
  </code></pre>
  
  <p>Inside the <code>index.html</code> in web, I made a button that opens <code>http://helloworld</code> when clicked on. However, my button ends up going to <code>helloworld.com</code> instead of the correct service. Both services work fine when I do <code>localhost:5001</code> and <code>localhost:5000</code>. Am I missing something?</p>