title: Docker rootfs_linux.go permission denied when mounting /proc
body: <p>I'm using <a href="http://meteor-up.com/" rel="noreferrer">meteor-up</a> to deploy to docker instances inside an LXD container. When it attempts to bring up a MongoDB docker instance, it fails with the following error:</p>
  
  <p><code>docker: Error response from daemon: oci runtime error: container_linux.go:265: starting container process caused "process_linux.go:368: container init caused \"rootfs_linux.go:57: mounting \\\"proc\\\" to rootfs \\\"/var/lib/docker/vfs/dir/20a621a73755db3f4030bc67bbf7ff9540bd1d63bb348d8be440d8ca63d3c922\\\" at \\\"/proc\\\" caused \\\"permission denied\\\"\"".</code></p>
  
  <p>I've tried deploying as the <code>ubuntu</code> user to my LXD container, and as <code>root</code>, and that hasn't helped. There's obviously some permissions issue here, but I don't know where to start debugging this problem.</p>