title: Docker build can't find docker to run tests
body: <p>I have a NodeJS application that is using <code>ioredis</code> to connect to redis and publish data and other redisy things. </p>
  
  <p>I am trying to write a component test against redis and was able to create a setup/teardown script via jest that runs redis via docker on a random port and tears it down when the tests are done via <code>docker run -d -p 6379 --rm redis</code> and <code>docker stop {containerId}</code>. </p>
  
  <p>This works great locally, but we have the tests running in a multi-stage build in our Dockerfile: 
  <code>RUN yarn test
  </code></p>
  
  <p>which I try to build via <code>docker build .</code> it goes great until it gets to the tests and then complains with the following error - <code>/bin/sh: docker: not found</code></p>
  
  <p>Hence, Docker is unavailable to the docker-build process to run the tests?</p>
  
  <p>Is there a way to run docker-build to give it the ability to spin up sibling processes during the process?</p>