gistfile1.rb

require 'csv'
module Puppet::Parser::Functions

  # we parse the precedence here because the best place to specify
  # it would be in site.pp but site.pp is only evaluated at startup
  # so $fqdn etc would have no meaning there, this way it gets evaluated
  # each run and has access to the right variables for that run
  newfunction(:lookup, :type => :rvalue) do |args|
    def var_to_fact str
      while str =~ /%\{(.+?)\}/
        fact = lookupvar $1
        raise(Puppet::ParseError, "Unable to found value for #{str}") if fact.nil?
        str.gsub!(/%\{#{$1}\}/, fact)
      end
      str
    end

    # what are we looking for?
    lookup_name = args[0]
    # hacky hacky line, but otherwise the value of lookup_order inside puppet will be changed!!
    order = lookupvar('lookup_order').join("!LoOKUpp!").split("!LoOKUpp!").map { |var| var_to_fact var }
    env = lookupvar('environment').to_sym

    # search through puppet module path and lookup order
    datafiles = Array.new
    begin
      Puppet.settings.instance_variable_get(:@values)[env][:modulepath].split(":").each do |module_path|
        # where our CSV file is located at
        order.each do |csv_file|
          file = "#{module_path}/#{csv_file}.csv"
          debug "scanning if #{file} exists"
          datafiles << file if File.exists?(file)
        end
      end
    rescue
      raise Puppet::ParseError, "Something went wrong while looking for a datafile for #{lookup_name} - $1"
    end

    debug "Found the following relevant data files: #{datafiles}"
    # parse our CSV files

    found = false
    result = ""
    datafiles.each do |file|
      begin
        parser.watch_file file
        next if found
        debug "scanning #{file}"
        result = CSV.read(file).find_all{ |r| r[0] == lookup_name }
        if result.size > 0
          found = true
          result = result.first[1..-1] # result values are in a nested array, removing one layer.
          result.map { |r| var_to_fact r } # replace values to facts if required.
        end
      rescue
        raise Puppet::ParseError, "Something went wrong while parsing #{file} - $1"
      end
    end

    if not found or result.size == 0
      raise Puppet::ParseError, "unable to find value for #{lookup_name}"
    else
      debug "Found: #{result}"
      return result
    end
  end
end