Update nagios configuration from puppetdb using stock puppet nagios_ resources.

nagiosdb.rb

#!/usr/bin/env ruby
#
# Nagios/PuppetDB config generator
# https://gist.github.com/jfryman/6290985
#
#   Based on concept from puppetdb-external-naginator
#   https://github.com/favoretti/puppetdb-external-naginator
#
# Generates nagios configs from puppet(db) exported resources.
#
require 'rubygems'
require 'json'
require 'httparty'
require 'fileutils'

module Nagios
  class PuppetDB
    include HTTParty
    base_uri 'https://your_puppetdb_server:8081'
    format :json

    OBJECTS = %w(
      host
      hostgroup
      hostescalation
      hostdependency
      hostextinfo
      service
      servicegroup
      serviceescalation
      servicedependency
      serviceextinfo
      contact
      contactgroup
      timeperiod
      command
    )

    TARGET='/etc/nagios/conf.d'
    CONFDIR='/etc/nagios'
    TMPDIR='/tmp/nagios/conf.d'
    TMPCONFIG='/tmp/nagios/nagios_tmp.cfg'
    LOCKFILE="/tmp/#{File.basename $0}.lock"
    CANARY="/tmp/nagiosdb_ok"
    NAGIOS_BIN='/usr/sbin/nagios'

    def self.lock
      begin
        File.open(LOCKFILE, File::RDWR|File::CREAT, 0644).flock(File::LOCK_EX)
      rescue => e
        puts "Something went horribly wrong while trying to setup a lock #{e}"
        bailout 1
      end
    end

    def self.unlock
      begin
        FileUtils.rm_rf LOCKFILE
      rescue => e
        puts "Something went horribly wrong while trying to remove a lock. #{e}"
        bailout 1
      end
    end

    def self.locked?
      begin
        File.exists? LOCKFILE
      rescue => e
        puts "Something went horribly wrong while trying to check if the lock exists. #{e}"
        bailout 1
      end
    end

    def self.search(endpoint, query = nil)
      begin
        options = Hash.new
        options[:headers] = { 'Accept' => 'application/json' }
        options[:query] = URI::encode("query=#{query}") if query
        options[:timeout] = 30
        get(endpoint, options)
      rescue => e
        puts "Something went horribly wrong while trying to search PuppetDB #{e}"
      end
    end

    def self.setup
      begin
        FileUtils.rm_rf TMPDIR unless File.exists? TMPDIR
        FileUtils.mkdir_p TMPDIR
        OBJECTS.each { |o| Dir.mkdir(File.join(TMPDIR, "#{o}.d")) }
      rescue => e
        puts "Something went horribly wrong while trying to setup nagios config sync. #{e}"
        bailout 1
      end
    end

    def self.teardown
      FileUtils.rm_rf TMPDIR
    end

    def self.collect_resources(resource)
      query = [
        'and',
          ['=', 'type', "Nagios_#{resource}"],
          ['=', ['node', 'active'], true],
          ['not',
            ['=', ['parameter', 'ensure'], 'absent']
          ],
        ]
      self.search('/v2/resources', query.to_json)
    end

    def self.rsync(apply = true)
      flags = '-avrc'
      flags += 'n' unless apply

      puts `rsync #{flags} --delete #{TMPDIR}/ #{TARGET}/`
      `find #{TARGET} -type d | xargs chmod 755`
      `find #{TARGET} -type f | grep .cfg | xargs chmod 444`
    end

    def self.valid_config?
      begin
        FileUtils.cp "#{CONFDIR}/nagios.cfg", TMPCONFIG
        text = File.read(TMPCONFIG)
        text.gsub!(/#{TARGET}/, "#{TMPDIR}")
        File.write(TMPCONFIG, text)

        nagios_validation = `#{NAGIOS_BIN} -v #{TMPCONFIG}`
        if $? != 0
          puts "You should checkout these errors:"
          puts
          puts nagios_validation
          false
        else
          true
        end
      rescue => e
        puts "Something went horribly wrong while trying to validate nagios config. #{e}"
        bailout 1
      ensure
        FileUtils.rm_rf TMPCONFIG
      end
    end

    def self.reload_nagios
      puts `/etc/init.d/nagios reload`
    end

    def self.assemble_configs
      OBJECTS.each do |o|
        resources = self.collect_resources(o)
        resources.each do |r|
          File.open("#{TMPDIR}/#{o}.d/#{File.basename(r['title'])}.cfg", 'w') do |f|
            my_params = self.filter_resource_params(r['parameters'])
            my_params = self.simulate_name_from_title(o, r['title'], my_params)
            my_params = Hash[my_params.sort]
            body = my_params.map { |(k,v)|
             "#{'%-35s' % k} #{v.respond_to?(:join) ? v.join(',') : v}"
            }

            f.write(<<-EOD
define #{o} {
  #{body.join("\n  ")}
}
                    EOD
            )
         end
        end
      end
    end

    def self.filter_resource_params(params)
      params.reject do |(k,v)|
        %w(audit before loglevel noop ensure
           notify require schedule stage subscribe tag).include?(k)
      end
    end

    def self.simulate_name_from_title(object_type, title, params)
      unnamed_types = %w(service servicedependency hostdependency hostescalation 
                         hostextinfo serviceextinfo)
      if !unnamed_types.include?(object_type) && params['register'] != '0'
        params["#{object_type}_name"] ||= title
      end
      params['name'] ||= title
      return params
    end

    def self.nsync?
      output = `diff -drupN #{TARGET} #{TMPDIR}`
      if $? != 0
        puts "Nagios Updates:"
        puts "---------------"
        puts
        puts output
        false
      else
        puts "Nagios configs are synced"
        true
      end
    end

    def self.update_canary
      FileUtils.touch(CANARY)
    end

    def self.update_configs
      if self.valid_config?
        self.rsync
        self.reload_nagios
      else
        bailout 1
      end
    end

    def self.run(noop = false)
      begin
        unless self.locked?
          self.lock
          self.setup
          self.assemble_configs

          if noop
            bailout 1 unless self.nsync?
            update_canary
            bailout 0
          else
            self.update_configs unless self.nsync?
            update_canary
          end
        else
          puts "Hold your horses, hoss. Shit be happening already..."
          exit 1
        end

        bailout 0
      rescue => e
        puts "Something went horribly wrong while trying to do the needful. #{e}"
        bailout 1
      end
    end

    def self.bailout(exit_code)
      self.unlock
      self.teardown
      exit exit_code
    end
  end
end

if ARGV.include?('noop')
  Nagios::PuppetDB.run(true)
else
  Nagios::PuppetDB.run
end