Heroku Env – Easy heroku environment variables in development mode

Heroku Env fetchs all your heroku config variables and set up them in your
local development environment.

Add the the gem to your Gemfile

gem "heroku_env"

Configure config/heroku_env.yml optionaly to customize the variables
without changing herokus or your variables

development:
  GOOGLE_ANALYTICS: nil
  FOO: BAR

You can generate a default heroku_env.yml file with a rake task:
rake heroku_env:config:create