title: GCloud: unable to listen on the Port defined by env variable
body: <p>I am trying to deploy on Google Cloud Platform for the first time using the following two tutorials:</p>
  <ol>
  <li><a href="https://cloud.google.com/cloud-build/docs/quickstart-build" rel="nofollow noreferrer">Gcloud build quickstart</a></li>
  <li><a href="https://cloud.google.com/cloud-build/docs/quickstart-deploy" rel="nofollow noreferrer">Gcloud deploy quickstart</a></li>
  </ol>
  <p>However, when running the final command <code>gcloud builds submit --config cloudbuild.yaml</code>, where <strong>cloudbuild.yaml</strong> is the name of the yaml file as per tutorial, throws the following error:</p>
  <p><code> Cloud Run error: Container failed to start. Failed to start and then listen on the port defined by the PORT environment variable. Logs for this revision might contain more information.</code></p>