title: Docker build failing with "failed to compute cache key: "/tmp/mvnrepository.tgz" not found: not found"
body: <p>I am doing a docker build on a Dockerfile and its failing on the below step</p>
  <pre><code>COPY /tmp/mvnrepository.tgz /opt/mvnrepository.tgz
  </code></pre>
  <p>I've tried specifying the file name with docker build -f Dockerfile but I still get the error. I've tried building it from the parent directory with the path to the dockerfile included and the file name like below but i still get the error</p>
  <pre><code>cd /home/parentdirectory
  docker build . -f /childdirectory/Dockerfile
  </code></pre>