lite_config.rb

require 'yaml'

# Simple loading of environment-namespaced config files with local overrides.
#
#   LiteConfig(:foobar)
#
# loads and caches the current environment section from:
#
#   config/foobar.yml
#
# The file must contain a yaml hash with environments for top-level keys.
#
# Config files can be overridden by adding _local to the filename:
#
#   config/foobar.yml
#
# Local overrides are intended for individual developer boxes and thus 
# should be left out of version control.
module LiteConfig
  extend self

  def fetch(name)
    name = name.to_sym
    @configs ||= {}
    @configs.key?(name) ? @configs[name] : (@configs[name] = load(name))
  end

  private

  def load(name)
    filename = active_config_filename(name)
    config = YAML.load_file(filename)[app_env]
    raise "Oops, no #{app_env} config found for #{name} in #{filename}" unless config
    config
  end

  def config_path
    @config_path ||= File.join(app_root, 'config')
  end

  def config_filename(name)
    File.join(config_path, name.to_s + '.yml')
  end

  def local_config_filename(name)
    config_filename(name).gsub(/.yml$/, '_local.yml')
  end

  def active_config_filename(name)
    File.exist?(local_config_filename(name)) ? local_config_filename(name) : config_filename(name)
  end

  def app_root
    defined?(Rails) ? Rails.root : `pwd`.strip
  end

  def app_env
    @app_env ||=
    if defined?(Rails)
      Rails.env
    elsif ENV['RAILS_ENV']
      ENV['RAILS_ENV']
    elsif ENV['RACK_ENV']
      ENV['RACK_ENV']
    else
      'development'
    end
  end
end

def LiteConfig(name)
  LiteConfig.fetch(name)
end