title: ingensi/play-framework image repetitive downloads
body: <p>I have docker running on a windows box successfully. When I try to <code>docker build .</code> an image, docker downloads a lot of large image files in step 1.I have no problem with this. However, the last time I tried, I got an unexpected interruption when all but one image file was remaining to download. <br> When I built again, all the downloads started afresh and this has happened again and again. My question is, does docker not cache the already downloaded files somewhere or is there not a way to avoid this repetitive download? <br> Here is my <code>Dockerfile</code></p>
  
  <pre><code># Dockerfile
  FROM ingensi/play-framework
  COPY activator.sh /activator.sh
  EXPOSE 8000
  RUN mkdir /app
  WORKDIR /app
  CMD ["activator","run"]
  </code></pre>
  
  <p>This is the console output on running <code>docker build .</code></p>
  
  <pre><code>Sending build context to Docker daemon 7.543 MB
  Step 1 : FROM ingensi/play-framework
  latest: Pulling from ingensi/play-framework
  a3ed95caeb02: Pull complete
  6b8936f53711: Downloading 10.77 MB/77.28 MB
  ba9b63c22e85: Downloading 8.222 MB/18.17 MB
  c8f760722057: Download complete
  05c3b10b9cd9: Waiting
  eea97537ef12: Waiting
  40254e2b433f: Waiting
  66be6357e6af: Waiting
  ca0f372c20c8: Waiting
  1f9b623e6354: Waiting
  </code></pre>
  
  <p>The image files being downloaded are always the same and appear in the same order judging by the codes on the left and file sizes.</p>