Two Chef additional instructions (0.8 version)

cookbook.rb

class Chef
  class Node
    # Recursively descend the Node run list and look for the "recipe"
    # node.erun_list('recipe[accountr]')
    #
    def erun_list?(search, run_list=self.run_list )
      Chef::Log.debug("erun_list? for #{search} in #{run_list}.")
      in_recipe = run_list.run_list.find { |r| r==search}
      if in_recipe != nil
        Chef::Log.debug("Found #{search} in base run_list (#{run_list.run_list})...")
      end
        
      return true if in_recipe != nil
      run_list.roles.each do |role_name|
        role = Chef::Role.load(role_name)
        if erun_list?(search, role.run_list)
          Chef::Log.debug("Found #{search} in role #{role_name}.")
          return true
        else
          Chef::Log.debug("#{search} not found in role #{role_name}.")
        end
      end 
      return false
    end  
  end
  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 = []
          nodes << search(:node, "run_list:"+search)
          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

Unfortunately, I haven't had the opportunity to test this code against version 0.9. However, I've filled a bug at Chef to ask Chef's developer to include this feature in Chef's core features ( http://tickets.opscode.com/browse/CHEF-1355 )...