title: Does pulling a public image from Docker Hub require authentication?
body: <p>I have a CI/CD pipeline running.  During the run, I'm using the <a href="https://github.com/spotify/docker-maven-plugin" rel="nofollow noreferrer">Spotify docker-maven-plugin</a> to do the Docker build.</p>
  
  <p>Recently my builds have begun failing when it tries to pull Payara Micro version 172 as the first line in my Dockerfile:</p>
  
  <pre><code>FROM payara/micro:172
  </code></pre>
  
  <p>I see this in my logs:</p>
  
  <pre><code>74297 [INFO] 53853 [INFO] Building image my.private.repo.io/arglebargle/foobar:38a635da5622d90dc09d71757c734fe52539bac3
  75522 [INFO] Step 1 : FROM payara/micro:172
  76539 [INFO] 56095 [INFO] ------------------------------------------------------------------------
  76540 [INFO] 56095 [INFO] BUILD FAILURE
  76540 [INFO] 56095 [INFO] ------------------------------------------------------------------------
  76540 [INFO] 56096 [INFO] Total time: 55.094 s
  76540 [INFO] 56096 [INFO] Finished at: 2017-10-27T19:39:26Z
  76783 [INFO] 56336 [INFO] Final Memory: 52M/495M
  76783 [INFO] 56339 [INFO] ------------------------------------------------------------------------
  76785 [INFO] 56339 [ERROR] Failed to execute goal com.spotify:docker-maven-plugin:0.4.14:build (Build Docker image) on project foobar: Exception caught: Get https://registry-1.docker.io/v2/payara/micro/manifests/172: unauthorized: incorrect username or password -&gt; [Help 1]
  </code></pre>
  
  <p>I don't currently have anything in my Maven setup that says anything about logging in to Docker Hub, and again, this is a public image—so I would have expected it to just work (as it has been working in the past).</p>
  
  <p>What am I missing here?</p>