Chef Data Bag Helper Module to pop into recipes and easily get overrides from Data Bags.

data_bag_helper.rb

module DataBagHelper

#wrapper methods to insulate from change :)

  def node_run_list
     node.run_list.role_names.reverse
  end

  def current_data_bag_items
     data_bag current_cookbook_name
  end

  def current_cookbook_name
    self.cookbook_name 
  end

  #finds databags that match certain criteria for a node based on roles and possible arguments to method.
  # Recipe Usage Example: 
  # 
  # mongo_data_bag_config = find_matched_bag_items({:bagname => 'mongodb'}).first[:mongodb].first
  # node[:mongodb].current_override.merge!(mongo_data_bag_config)
  #
  # Example Data Bag for a Mongo recipe:
  #{
    #"id" : "db-multiapp-mongo-master-qa",
    #"enabled" : "true",
    #"environments" : ["qa"],
    #"required_roles" : ["db-mongo-master"],
    #"active_groups" : [{
      #"app" : {"enabled" : true},
      #"storage" : {"enabled" : true}
    #}],
    #"active_sudo_groups" : [{
      #"app" : {"enabled" : true}
    #}],
    #"mongodb" :[{
      #"replication" : {"master" : false},
      #"version" : "1.6.3",
      #"perform_backups" : true
    #}] 
  #}

  def find_matched_bag_items(arguments = {})
      matched_items = [] 
      Chef::Log.debug "In use_data_bag method with arguments: #{arguments.inspect} ..."
      # setup some useful defaults
      bagname = arguments["bagname"] || arguments[:bagname] || current_cookbook_name
      run_list = arguments["run_list"] || arguments[:run_list] || node_run_list
      filter = arguments["filter"] || arguments[:filter] || "enabled:true"
      raise "find_matched_bag_items required arguments not found" unless bagname && run_list
      
      # find items that meet filter, usually enabled:true
      search(bagname.to_sym, filter)  do |bagitem|                     
         
         Chef::Log.debug "Iterating over bagitem: #{bagitem.id}"
         # find any required roles
         required_roles =  bagitem["required_roles"] || []             
         
         # find environments required
         environments = bagitem["environments"] || []

         # skip this bagitem IF hnvironment is specified AND environment is NOT found in run_list
         unless environments.size > 0 && node_run_list.select {|ea| environments.include? ea}.empty? 

           # the current data_bag bagitem matches a run_list bagitem OR all required_roles are found in run_list 
           if (required_roles.size > 0 && required_roles.select{|ea|  run_list.include? ea }.size == required_roles.size) ||  run_list.include?(bagitem.id)
             Chef::Log.debug "All criteria met,storing databag item: #{bagitem.inspect}"           
            matched_items << bagitem  #since we have reversed the order of run list the last, or highest priority item to match will return its bag
           else
            Chef::Log.debug "One or more of the required_roles: #{required_roles.join(' | ')} was NOT in run_list: #{run_list.join(' | ')}"
           end
          else
            Chef::Log.debug "None of the nodes run_list environment bagitems  #{run_list.join(' | ')}, match the data_bag environments: #{environments.join(' | ')}"
          end
      end
      return matched_items
  end


end