title: gitignore config file for Github but not Heroku
body: <p>Got an application that reads from a local <code>config.json</code> file. I have two remote repos - Github and Heroku. The Github repo is public but the contents of the config file are private - therefore I've added a <code>.gitignore</code> to prevent this file from being pushed.</p>
  
  <p>However, when I push the app to Heroku I need the config file to be pushed so that the application can work - how do I deal with this situation?</p>
  
  <p><strong>Note:</strong> I'm reluctant to use Config vars as there are lots of settings in the config file.</p>