title: gcloud ping attempt failure with performing a 'docker push'
body: <p>I ran the following command</p>
  
  <pre><code>gcloud preview docker push gcr.io/project-name/an-image
  </code></pre>
  
  <p>And I got the following error.  Does anyone know how I fix that or what it means?  All I was doing was following the standard examples just to learn how it works...  Thanks :)</p>
  
  <p>FATA[0010] Error: v1 ping attempt failed with error: Get <a href="https://gcr.io/v1/_ping" rel="nofollow">https://gcr.io/v1/_ping</a>: dial tcp: i/o timeout. If this private registry supports only HTTP or HTTPS with an unknown CA certificate, please add <code>--insecure-registry gcr.io</code> to the daemon's arguments. In the case of HTTPS, if you have access to the registry's CA certificate, no need for the flag; simply place the CA certificate at /etc/docker/certs.d/gcr.io/ca.crt</p>
  
  <p>ERROR: (gcloud.preview.docker) A Docker command did not run successfully.
  Tried to run: 'docker push gcr.io/project-name/an-image'
  Exit code: 1</p>