title: How can I speed up Docker's slow "build" process?
body: <p>For example,</p>
  
  <pre><code>#!/bin/bash
  touch a b c d
  docker pull alpine
  # This SHOULD take the fraction of a second only
  docker build --no-cache -t test -f - . &lt;&lt;EOF
  FROM alpine
  COPY a /
  COPY b /tmp
  COPY c /var
  COPY d /etc
  EOF
  </code></pre>
  
  <p>This is a basic <code>docker build</code> command which adds four empty files to the image. Each COPY step takes about one second. Especially for manual testing, this is annoying. It is not <em>very</em> slow, but I do not understand the reason for the unnecessary waiting time.</p>
  
  <p>Why, and how can I speed this up?</p>