What does RACK_ENV do in a Rails application?

Question

I already have a Rails application. The guy before setting these environment variables:

...
export RACK_ENV=none                                                                                                                  
export RAILS_ENV=production
...

What does it do RACK_ENV=none? I can’t find the documentation anywhere. Do I need to install it in a Rails application, or can I just remove this export?

Answer 1

IMHO this is useless.

To find the current environment, the Rails application first looks for the environment variable RAILS_ENV, and then for the environment variable RACK_ENV, then it is equal by default 'development'.