Rails 3 YAML Configuration Loader

config.yml

# config/config.yml

defaults: &defaults
  key: value
  regexp: !ruby/regexp /pattern/

development:
  <<: *defaults
  
test:
  <<: *defaults
  
production:
  <<: *defaults
  key: override value

example.rb

# Access via symbol or string
puts APP_CONFIG[:key]
puts APP_CONFIG['key']

# Symbolize all keys when using to config other Rails components
ActionMailer::Base.smtp_settings = APP_CONFIG[:mailer][:smtp_settings].symbolize_keys
ActionMailer::Base.default APP_CONFIG[:mailer][:defaults].symbolize_keys

load_config.rb

# config/initializers/load_config.rb

config_file = "#{Rails.root}/config/config.yml"
APP_CONFIG = YAML.load_file(config_file)[Rails.env].with_indifferent_access if File.exists?(config_file)