Settingslogicを使ってconfig.yml, config.local.yml運用してみる ref: http://qiita.com/sawanoboly/items/1d776006ed24513e1b55

app.rb

require 'settingslogic'

class EnvSettings < Settingslogic
  source File.expand_path('../config.yml', __FILE__)
end

if File.exist?(File.expand_path('../config.local.yml', __FILE__))
  class EnvLocalSettings < Settingslogic
    source File.expand_path('../config.local.yml', __FILE__)
  end
  EnvSettings.merge!(EnvLocalSettings)
end

puts EnvSettings[:hoge]

config.local.yml

hoge: mogemoge

config.yml

hoge: <%= ENV['HOGEHOGE'] %>

file2.txt

 $ HOGEHOGE=moge ruby ./app.rb 
moge

file4.txt

$ HOGEHOGE=moge ruby ./app.rb 
mogemoge