/usr/local/bin/facter

facter.rb

#! /usr/bin/env ruby
require 'json'

ENV['facter_cache'] ||= `/opt/puppetlabs/bin/facter --show-legacy --no-external-facts --json`

cache = JSON.parse(ENV['facter_cache']) rescue {}
value = ARGV.first.split('.').reduce(cache) do |collector, key|
  break unless collector.keys.include? key
  collector[key]
end

value ||= `/opt/puppetlabs/bin/facter --show-legacy --puppet #{ARGV.first}`

print value