title: Selenium 'Chrome failed to start: exited abnormally' error
body: <p>I am following <a href="https://github.com/RobCherry/docker-chromedriver/blob/master/Dockerfile" rel="noreferrer">https://github.com/RobCherry/docker-chromedriver/blob/master/Dockerfile</a> as an example and I have the following in my docker file:</p>
  
  <pre><code>RUN CHROMEDRIVER_VERSION=`curl -sS chromedriver.storage.googleapis.com/LATEST_RELEASE` &amp;&amp; \
      mkdir -p /opt/chromedriver-$CHROMEDRIVER_VERSION &amp;&amp; \
      curl -sS -o /tmp/chromedriver_linux64.zip http://chromedriver.storage.googleapis.com/$CHROMEDRIVER_VERSION/chromedriver_linux64.zip &amp;&amp; \
      unzip -qq /tmp/chromedriver_linux64.zip -d /opt/chromedriver-$CHROMEDRIVER_VERSION &amp;&amp; \
      rm /tmp/chromedriver_linux64.zip &amp;&amp; \
      chmod +x /opt/chromedriver-$CHROMEDRIVER_VERSION/chromedriver &amp;&amp; \
      ln -fs /opt/chromedriver-$CHROMEDRIVER_VERSION/chromedriver /usr/local/bin/chromedriver
  
  RUN curl -sS -o - https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add - &amp;&amp; \
      echo "deb http://dl.google.com/linux/chrome/deb/ stable main" &gt;&gt; /etc/apt/sources.list.d/google-chrome.list &amp;&amp; \
      apt-get -yqq update &amp;&amp; \
      apt-get -yqq install google-chrome-stable &amp;&amp; \
      rm -rf /var/lib/apt/lists/*
  
  ENV DISPLAY :20.0
  ENV SCREEN_GEOMETRY "1440x900x24"
  ENV CHROMEDRIVER_PORT 4444
  ENV CHROMEDRIVER_WHITELISTED_IPS "127.0.0.1"
  ENV CHROMEDRIVER_URL_BASE ''
  EXPOSE 4444
  </code></pre>
  
  <p>To create the driver I am doing:</p>
  
  <pre><code>webdriver.Chrome()
  </code></pre>
  
  <p>But I get:</p>
  
  <pre><code>selenium.common.exceptions.WebDriverException: Message: unknown error: Chrome failed to start: exited abnormally
    (Driver info: chromedriver=2.33.506092 (733a02544d189eeb751fe0d7ddca79a0ee28cce4),platform=Linux 4.4.27-boot2docker x86_64)
  </code></pre>
  
  <p>Do I have to do anything else to allow Chrome to start?</p>