title: Not able to run express-gateway on heroku - failed to bind to $PORT
body: <p>I'm trying to have the basic example express-gateway running on Heroku</p>
  <pre class="lang-yaml prettyprint-override"><code>    http:
        port: ${HTTP_PORT:-8080}
        hostname: ${HOST:-localhost}
      admin:
        port: 9876
        host: localhost
      apiEndpoints:
        api:
          host: 'localhost'
          paths: '/ip'
      serviceEndpoints:
        httpbin:
          url: 'https://httpbin.org'
  ...
  </code></pre>
  <p>Looking the logs I got the following error:</p>
  <pre><code>2021-02-15T18:53:09.947569+00:00 heroku[web.1]: Error R10 (Boot timeout) -&gt; Web process failed to bind to $PORT within 60 seconds of launch
  </code></pre>
  <p>Any ideas?</p>