title: How my app is published on WWW without a Web Server?
body: <p>I'm studing Docker and i just created a Rails app following the guide here <a href="https://docs.docker.com/compose/rails/" rel="nofollow noreferrer">https://docs.docker.com/compose/rails/</a> , the image used in this guide use the PUMA as server APP. When i up my container the app is already published on WWW by myipnumber:3000.</p>
  
  <p>So here is my doubt, how is possible to my app is published on WWW without a Web Server like NGINX/Apache since these are aparenttly not installed in my host or container? (maybe they are but i cant see).</p>