newrelic_passenger_agent

#! /usr/bin/env ruby

#
# This Agent uses the passenger commands to track the number of running
# and active passenger processes as well as their memory usage
#
# The inital version was mainly based on https://github.com/barttenbrinke/munin-plugins-rails
#

require "rubygems"
require "bundler/setup"

require "newrelic_plugin"

require File.join(File.dirname(__FILE__), 'lib/passenger_memory_stats_parser')
require File.join(File.dirname(__FILE__), 'lib/passenger_status_parser')

module PassengerAgent

  class ConfigurationError < StandardError ; end

  class Agent < NewRelic::Plugin::Agent::Base

    agent_guid "net.theimp.newrelic.passenger"
    agent_version "0.2.3"
    agent_config_options :passenger_status, :passenger_memory_stats, :passenger_version
    agent_human_labels("Passenger") { "Passenger on #{`hostname`}" }


    #
    # This method is called on initializing the Agent and should check configuration and select version depending regexes
    #
    def setup_metrics
      valid_passenger_versions = [3, 4, 5]

      raise ConfigurationError, "passenger_version config variable must be set" unless defined?(passenger_version)
      raise ConfigurationError, "Passenger version must be one of #{valid_passenger_versions}" unless valid_passenger_versions.include?(passenger_version)

      @memory_stats_parser = PassengerMemoryStatsParser.new
      @status_parser = PassengerStatusParser.new(passenger_version)
    end


    def report_passenger_status
      @status_parser.output_to_parse = run_command(passenger_status)

      report_metric "passenger.processes.max", "Processes", @status_parser.processes_max
      report_metric "passenger.processes.running", "Processes", @status_parser.processes_running
      report_metric("passenger.processes.active", "Processes", @status_parser.processes_active) if passenger_version.eql?(3)
      report_metric "passenger.queue.waiting", "Requests", @status_parser.queue_waiting
      report_metric "passenger.sessions.total", "Sessions", @status_parser.sessions_total
    end


    def report_passenger_memory_stats
      @memory_stats_parser.output_to_parse = run_command(passenger_memory_stats)

      report_metric "passenger.memory.total", "Megabyte", @memory_stats_parser.passenger_memory_total
      @memory_stats_parser.passenger_memory_per_app.each do |app, memory_usage|
        report_metric "passenger.memory.#{app}", "Megabyte", memory_usage
      end
    end


    def poll_cycle
      
      report_passenger_status

      report_passenger_memory_stats

    end

    
    private      

    def run_command(command)
      
      #uncomment to test example_output files
      #return File.read("example_output/#{command.split('/').last}_version-#{passenger_version}")

      result = `#{command}`

      unless $?.success?
        $stderr.puts "failed executing #{command}"
        exit 1
      end

      result
    end


  end

  #
  #Starting via daemons needs to load the correct config file
  #
  NewRelic::Plugin::Config.config_file = File.dirname(__FILE__) + '/config/newrelic_plugin.yml'

  #
  # Register this agent with the component.
  #
  NewRelic::Plugin::Setup.install_agent :passenger, PassengerAgent

  #
  # Launch the agent; this never returns.
  #
  NewRelic::Plugin::Run.setup_and_run

end