title: `gcloud compute copy-files`: permission denied when copying files
body: <p>I'm having a hard time copying files over to my Google Compute Engine. I am using an Ubuntu server on Google Compute Engine.</p>
  
  <p>I'm doing this from my OS X terminal and I am already authorized using <code>gcloud</code>.</p>
  
  <pre><code>local:$ gcloud compute copy-files /Users/Bryan/Documents/Websites/gce/index.php example-instance:/var/www/html --zone us-central1-a
  Warning: Permanently added '&lt;IP&gt;' (RSA) to the list of known hosts.
  scp: /var/www/html/index.php: Permission denied
  ERROR: (gcloud.compute.copy-files) [/usr/bin/scp] exited with return code [1].
  </code></pre>