title: Docker daemon "unknown: Authentication is required" message
body: <p>I installed docker-toolbox on my Mac. </p>
  
  <p>I ran the following command to login to our private registry (JFrog Artifactory 4.1). Provided username, email and password when requested and login succeeded.</p>
  
  <pre><code>docker login &lt;registry url&gt;
  </code></pre>
  
  <p>This created a file <strong>~/.docker/config.json</strong> on my system having some representation of my credentials.</p>
  
  <p>Pulling and pushing images worked fine for a while. At some point later, when i tried to pull an image, i ended up with the following</p>
  
  <pre><code>b745547eea8f: Retrying in 1 second
  8e68617bcad0: Retrying in 1 second
  d0a4a553178b: Retrying in 1 second 
  4ef6bb1e3944: Retrying in 1 second 
  5f70bf18a086: Retrying in 1 second 
  69bd93b9db4e: Waiting
  unknown: Authentication is required
  </code></pre>
  
  <p>Retried multiple times with no luck. Ran "docker login" again and retried. Same issue was seen for 2-3 minutes. After 2-3 minutes, "<strong>docker pull</strong>" worked.</p>
  
  <p><strong>Questions</strong>:</p>
  
  <ul>
  <li>After ~/.docker/config.json file is created, do these credentials expire after a certain amount of time? If yes, how can i increase the expiration time.</li>
  <li>Why did "docker pull" fail for first 2-3 minutes after logging in for the second time. Does this have anything to do with time on my local machine and VM on VirtualBox created by docker-toolbox?</li>
  </ul>
  
  <p>We are about to open our private registry to everyone in our company. Don't want people to face these things while pulling images.</p>