For each and every Rails app, I always needed some kind of app configuration file. Something simple, at best as a YML-file. With some research on google and stackoverflow I ended up with the following solution. It’s neither new nor groundbreaking and probably someone else has already done it that way. 

This solution allows to:

• Have a “default” configuration
• For every environment changing some attributes 
• No need to copy all attributes for every environment 
• It allows nested attributes for easier access and better readability. (eg. homepage>head)
• It’s hashed
• You can access the AppConfig from everywhere in your rails app by using “AppConfig[:homepage][:head]”

(Tested with Rails 3.2.1)

New file at ‘config/app_config.yml’:

defaults:
  homepage:
    head: peterkling
    subline: "webdesign: analyse | konzeption | gestaltung | umsetzung"
development:
  homepage:
    head: "peterkling [DEV]"
test:
production:

New file at ‘lib/appconfig.rb’:

config = ActiveSupport::HashWithIndifferentAccess.new(YAML.load_file("#{Rails.root.to_s}/config/app_config.yml"))

if !config[Rails.env].nil?
  AppConfig = config[:defaults].deep_merge(config[Rails.env])
else
  AppConfig = config[:defaults]
end

Add to environment.rb

load 'lib/appconfig.rb'

Access AppConfig eq. in views:

 <h1><%= AppConfig[:homepage][:head]%></h1>
 <h2><%= AppConfig[: homepage][:subline]%></h2>