title: gcloud docker 409 image conflict error with Node.js
body: <p>I've got an Express Node app that I'm using with gcloud. When I am running locally using:</p>
  
  <pre><code>gcloud preview app run .
  </code></pre>
  
  <p>I am getting this:</p>
  
  <pre><code>WARNING: Image Id 2d30351c6647 cannot be removed: 409 Client Error:     
  Conflict ("Conflict, cannot delete 404cc995b0da because the running 
  container 837a44cae1ee is using it, stop it and use -f to force").
  </code></pre>
  
  <p>The app is running pretty slowly most of the time. When I save, it goes through a slow health check which looks like this:</p>
  
  <pre><code>INFO: [default] Detected file changes:
  /path/to/server.js
  INFO: Building image &lt;appID&gt;.default.1...
  INFO: Waiting for instances to restart
  INFO: Health checks starting for instance 0.
  INFO: default: "GET /_ah/health?IsLastSuccessful=no HTTP/1.1" 503 -
  WARNING: All instances may not have restarted
  INFO: default: "GET /_ah/health?IsLastSuccessful=no HTTP/1.1" 503 -
  </code></pre>
  
  <p>And then I get the 409 image warning. It slows down considerably, and occasionally crashes all together. Any help is much appreciated.</p>