Custom Facts indirector to inject extra Hiera-based fact

puppetdb_with_network.rb

require 'puppet/indirector/facts/puppetdb'
require 'puppet/node/facts'
require 'hiera'

class Puppet::Node::Facts::PuppetdbWithNetwork < Puppet::Node::Facts::Puppetdb
  # Here we override the normal save, injecting a custom fact
  def save(args)
    name  = args.instance.name
    facts = args.instance.values
    facts.define_singleton_method(:lookupvar) do |key|
      self[key] || self[key.to_s]
    end

    begin
      config = Hiera::Config.load(Puppet['hiera_config'])
      config[:logger] = 'puppet'
      hiera = Hiera.new(:config => config)

      # For any Hiera lookup to inject as a fact, add it here
      network = hiera.lookup('network', nil, facts, nil, :priority)
      facts['network'] = network if network

      args.instance = Puppet::Node::Facts.new(name, facts)
    rescue
      # ignore
    ensure
      super(args)
    end
  end
end