title: gcloud auth login with Docker does not work as it says in documentation
body: <p>I've followed the Docker instructions from here exactly: <a href="https://cloud.google.com/sdk/#install-docker" rel="nofollow">https://cloud.google.com/sdk/#install-docker</a> (click Alternative Methods to find Docker instructions). </p>
  
  <p>But when I run:</p>
  
  <pre><code>docker run -t -i --volumes-from gcloud-config google/cloud-sdk gcloud compute instances list
  </code></pre>
  
  <p>I get:</p>
  
  <pre><code>docker run -t -i --volumes-from gcloud-config google/cloud-sdk gcloud compute instances list
  ERROR: (gcloud.compute.instances.list) You do not currently have an active account selected.
  Please run:
  
    $ gcloud auth login
  
  to obtain new credentials, or if you have already logged in with a
  different account:
  
    $ gcloud config set account &lt;account name&gt;
  
  to select an already authenticated account to use.
  </code></pre>
  
  <p>It doesn't look like it's picking up that I already authenticated. Any ideas?</p>