title: Configuring a production Angular application with file
body: <p>I have to build a proof of concept angular app that will make API calls to an application (software).
  My issue is that i'm testing calls on a local application and the customer application may have different settings : different entry points, different ports, etc.</p>
  <p>I would like to be able to define those parameters and read them from a file on a production server.
  I read about using environment files but i have to make the setup before building the app. I want to be able to make it after.</p>