Config files with YAML in rails.

rails_custom_config.rb

# config file whatever.yml

development:
  my_var: hello

test:
  my_var: hello

production:
  my_var: hello

# end of config file

# whatever.rb, put this in the initializers folder

# we add the Rails.env to load the config for this environment!
WHATEVER = YAML.load_file("#{Rails.root}/config/whatever.yml")[Rails.env]

# end of whatever.rb

# And then use it wherever you want in your rails app

puts WHATEVER['my_var']

# super easy!