Puppet master Rack middleware

config.ru

$0 = "master"
ARGV << "--rack"
ARGV << "--certname=#{File.read("/etc/puppet/certname").chomp}"

require 'puppet/application/master'

require 'base64'
require 'json'
require 'rack/utils'
require 'yaml'
require 'zlib'

class StuckInTheMiddleWithYou

  def initialize(app)
    @app = app
  end

  def call(env)

    params = Rack::Utils.parse_query(env["QUERY_STRING"], "&")
    facts = case params["facts_format"]
    when "b64_zlib_yaml"
      YAML.load(Zlib::Inflate.inflate(Base64.decode64(
        Rack::Utils.unescape(params["facts"]))))
    end

    # Change facts.
    if Puppet::Node::Facts === facts                                                                                                                             
      facts.values["foo"] = "bar"                                                                                                                                
    end

    params["facts"] = case params["facts_format"]
    when "b64_zlib_yaml"
      Rack::Utils.escape(Base64.encode64(Zlib::Deflate.deflate(
        YAML.dump(facts), Zlib::BEST_COMPRESSION)))
    end if facts
    env["QUERY_STRING"] = Rack::Utils.build_query(params)
    env["REQUEST_URI"] =
      "#{env["PATH_INFO"]}?#{env["QUERY_STRING"]}"

    status, headers, body = @app.call(env)

    object = case headers["Content-Type"]
    when /[\/-]pson$/ then JSON.parse(body.body.join)
    when /[\/-]yaml$/ then YAML.load(body.body.join)
    when "text/marshal" then Marshal.load(body.body.join)
    else body.body.join
    end

    # Change catalog.
    if Hash === object && "Catalog" == object["document_type"]
      object["data"]["resources"].unshift({
        "exported" => false,
        "title" => "apt-get update",
        "parameters" => {"path"=>"/usr/sbin:/usr/bin:/sbin:/bin"},
        "type" => "Exec",
      })
    end

    body = case headers["Content-Type"]
    when /[\/-]pson$/ then [JSON.generate(object)]
    when /[\/-]yaml$/ then [YAML.dump(object)]
    when "text/marshal" then [Marshal.dump(object)]
    else [object]
    end
    headers["Content-Length"] = Rack::Utils.bytesize(body.first)

    [status, headers, body]
  end

end

use StuckInTheMiddleWithYou

run Puppet::Application[:master].run