A fact for showing the classes in classes.txt

puppet_classes.rb

#!/usr/bin/ruby
# curl -G http://localhost:8080/v3/facts/puppet_classes

require 'facter'
require 'json'

hostname    = Facter.value(:hostname)
classes_txt = '/var/opt/lib/pe-puppet/classes.txt'
Facter.debug(classes_txt)
if File.exists?(classes_txt) then
  f = File.new(classes_txt)
  classes = Array.new()
  f.readlines.each do |line|
    line = line.chomp.to_s
    line = line.sub(' ','_')
    classes.push(line)
  end
  classes.delete('settings')
  classes.delete(hostname.to_s)
  Facter.add(:puppet_classes) do
    setcode do
      classes.sort.to_json
    end
  end
end

#!/opt/puppet/bin/ruby
require 'net/http'
require 'uri'
require 'json'

uri = URI('http://localhost:8080/v3/facts/puppet_classes')
response = Net::HTTP.get_response(uri)
facts = JSON.parse(response.body)

nodes = Hash.new
facts.each do |fact|
 value    = JSON.parse(fact['value'])
 certname = fact['certname']
 (nodes[value.join(",")] ||= []) << certname
end

nodes.each do |classes,nodes|
  puts '-' * 80
  puts "#{nodes.length}: #{nodes.join(',')}"
  puts '-' * 80
  puts classes.split(',').join("\n")
  puts '-' * 80
end

listing them out of puppetdb