aaa_load_app_config.rb

# config/initializers/aaa_load_app_config.rb
#
# Prefixed with "aaa_" so that it is loaded first and app configs can be used in later initializers

require 'ostruct'

::AppConfig = OpenStruct.new(YAML.load_file(Rails.root.join('config', 'app_config.yml')).with_indifferent_access)

app_config.yml

# config/app_config.yml
#
# Example:

twitter:
  username:
  password:

bitly:
  username:
  api_key:

mail:
  username:
  password:
  port: 587
  address: smtp.gmail.com
  from: