#!/usr/bin/env ruby

# Collects Apache metrics and submits them to Riemann
# More information can be found at http://httpd.apache.org/docs/2.4/mod/mod_status.html

# Removes whitespace from 'Total Accesses' and 'Total kBytes' for output to graphite

require File.expand_path('../../lib/riemann/tools', __FILE__)

class Riemann::Tools::ApacheStatus
  include Riemann::Tools
  require 'net/http'
  require 'uri'

  opt :uri, 'Apache Server Status URI', :default => 'http://localhost/server-status'

  def initialize
    @uri = URI.parse(opts[:uri]) + '?auto'
    # Sample Response with ExtendedStatus On
    # Total Accesses: 20643
    # Total kBytes: 36831
    # CPULoad: .0180314
    # Uptime: 43868
    # ReqPerSec: .470571
    # BytesPerSec: 859.737
    # BytesPerReq: 1827.01
    # BusyWorkers: 6
    # IdleWorkers: 94
    # Scoreboard: ___K_____K____________W_

    @scoreboard_map  = { '_' => 'waiting', 'S' => 'starting', 'R' => 'reading', 'W' => 'sending',
      'K' => 'keepalive', 'D' => 'dns', 'C' => 'closing', 'L' => 'logging', 'G' => 'graceful',
      'I' => 'idle', '.' => 'open' }
  end


  def get_scoreboard_metrics(response)
    results = Hash.new(0)

    response.slice! 'Scoreboard: '
    response.each_char do |char|
      results[char] += 1
    end
    Hash[results.map { |k, v| [@scoreboard_map[k], v] }]
  end

  def report_metrics(metrics)
    metrics.each do |k, v|
      report(
        :service  => "httpd #{k}",
        :metric   => v.to_f,
        :state    => 'ok',
        :tags     => ['httpd']
      )
    end
  end

  def get_connection
    response = nil
    begin
      response = Net::HTTP.get(@uri)
    rescue => e
      report(
        :service     => 'httpd health',
        :state       => 'critical',
        :description => 'Httpd connection error: #{e.class} - #{e.message}',
        :tags        => ['httpd']
      )
    else
      report(
        :service     => 'httpd health',
        :state       => 'ok',
        :description => 'Httpd connection status ok',
        :tags        => ['httpd']
      )
    end
    response
  end

  def tick
    unless (response = get_connection).nil?
      response.each_line do |line|
        metrics = Hash.new

        if line =~ /Scoreboard/
          metrics = get_scoreboard_metrics(line.strip)
        else
          key, value = line.strip.split(':')
          metrics[key.gsub(/\s/, '')] = value
        end
        report_metrics(metrics)
      end
    end
  end

end

Riemann::Tools::ApacheStatus.run