title: docker: driver failed programming external connectivity on endpoint webserver
body: <p>I am trying to run a docker example <a href="https://docs.docker.com/docker-for-mac/" rel="noreferrer">following this documentation</a></p>
  <p>This is my command:</p>
  <pre><code>docker run -d -p 80:80 --name webserver nginx
  </code></pre>
  <p>But I get this error:</p>
  <blockquote>
  <p>docker: Error response from daemon: driver failed programming external connectivity on endpoint webserver (bd57efb73c738e3b271db180ffbee0a56cae86c8193242fbc02ea805101df21e): Error starting userland proxy: Bind for 0.0.0.0:80: unexpected error (Failure EADDRINUSE).</p>
  </blockquote>
  <p>How do I fix this?</p>