cookbook.rb

class Chef
  module Mixin
    module Language
      # esearch(:node, 'role\[admin\]')
      # recursively search for this role/recipe in all roles
      def esearch(context, search)
        if context == :role
          ret = []
          # First solve all roles:
          roles = search(:role, search)
          if not roles.nil?
            roles.each do |role|
              ret << esearch(:role, "run_list:role\\[#{role.name}\\]")
            end
          end 
          ret << roles
          return ret.flatten
        elsif context == :node
          # Find all roles including this recipe
          nodes = []
          roles = esearch(:role, "run_list:"+search)
          roles.each do |r|
            nodes << search(:node, "run_list:role\\[#{r.name}\\]")
          end
          nodes.flatten!
          nodes.sort!
          # Unify by to_s value
          nodes = nodes.inject({}) do |hash,item|
             hash[item.to_s]||=item
             hash 
          end.values
          return nodes
        end
      end
    end
  end
end