title: Why does Docker build take long time in "Sending context to daemon" step?
body: <p>I am pretty new to the <code>Docker</code> world. I am running this command:</p>
  
  <p><code>docker build -t worker -f worker-Dockerfile-local .</code></p>
  
  <p>This is the content of the Docker file:</p>
  
  <pre><code>FROM centos
  MAINTAINER MyTeam
  
  RUN /usr/bin/getent group worker || /usr/sbin/groupadd -r worker
  RUN /usr/bin/getent passwd worker || /usr/sbin/useradd -r -g worker -s /sbin/nologin worker
  
  # INSTALL PIP
  RUN curl "https://bootstrap.pypa.io/get-pip.py" -o "get-pip.py"
  RUN python get-pip.py
  
  
  ADD . /code
  RUN pip install ./code
  </code></pre>
  
  <p>I get this message after starting this command:</p>
  
  <p><code>Sending build context to Docker daemon 2.942 GB</code></p>
  
  <p>My other builds take only a few seconds and the "Sending context to daemon" stage send only a few KB of data. I am not sure what's going on. Can someone help me out please?</p>