Can I tell foreman to reload the web app every time a request is made so I can develop decently?
Here's an adjusted version of Pendlepants solution. Foreman looks for an .env file to read environment variables. Rather than adding a wrapper, you can just have Foreman switch what command it uses to start things up:
In your Procfile:
By default, Foreman will read from .env (in Production), but in DEV just run this:
foreman start -e dev.env