title: Installing Python 3 Docker Ubuntu error command 'x86_64-linux-gnu-gcc
body: <p>I'm trying to create a dockerfile that uses Python 3. </p>
  
  <pre><code>FROM ubuntu:14.04
  RUN apt-get update
  RUN apt-get install -y python3 python3-dev python-pip
  RUN apt-get install -y libxml2-dev libxslt1-dev libpq-dev libjpeg-dev libfreetype6-dev zlib1g-dev
  RUN cd /var/projects/apps &amp;&amp; pip install -r requirements.txt
  </code></pre>
  
  <p>I get the error  fatal error: Python.h: No such file or directory when trying to install pillow in my requirements, why and I'm I installing python 3 correctly?</p>
  
  <pre><code>error:
  
  error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
  
  ----------------------------------------
  Cleaning up...
  Command /usr/bin/python -c "import setuptools, tokenize;__file__='/tmp/pip_build_root/pillow/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-C7CMih-record/install-record.txt --single-version-externally-managed --compile failed with error code 1 in /tmp/pip_build_root/pillow
  Storing debug log for failure in /root/.pip/pip.log
  INFO[0102] The command [/bin/sh -c cd /var/projects/app &amp;&amp; pip install -r requirements.txt] returned a non-zero code: 1
  </code></pre>