title: When do DockerHub auth tokens expire?
body: <p>When <code>docker login</code> succeeds an auth token is put in <code>~/.dockercfg</code>. We are considering deploying a <code>.dockercfg</code> file to EC2 instances to all running of containers against private repository images. The alternative would be to run <code>docker login</code> on the instances, but I would prefer to give instances an auth token as opposed to an account password.</p>
  
  <p>How long do the tokens issued by <code>docker.io</code> last before they expire?</p>