Comment by dhh

Rails will have custom configuration built-in from 4.2, but you can also just use the gem today: https://github.com/dhh/custom_configuration

Then you can centralize all your configuration in config/environments/* and config/initializers/. The best practice being that you set the configuration in config/environments/ and you read that configuration point and do something with it in config/initializers/*.

IMO, much nicer than messing with ENVs.