trends.rb

#!/usr/bin/env ruby
#
# simple rrd trending of http access logs
# Usage example:
#   trends.rb /var/log/messages

require "rubygems"
require "eventmachine"
require "eventmachine-tail"
require "rrd"


class Reader < EventMachine::FileTail
  def initialize(path, startpos=-1)
    super(path, startpos)
    puts "Tailing #{path}"
    @buffer = BufferedTokenizer.new
  end

  def receive_data(data)
    @buffer.extract(data).each do |line|
      @@counter += 1
    end
  end
end

def init_rrd
  rrd = RRD::Base.new('trends.rrd')
  if !File.exists?('trends.rrd')
    rrd.create :start => Time.now - 10.seconds, :step => 5.minutes do
      datasource "requests", :type => :gauge, :heartbeat => 10.minutes, :min => 0, :max => :unlimited
      archive :average, :every => 10.minutes, :during => 1.year
    end
  end
  rrd
end

def update_rrd(time, value)
  rrd = init_rrd
  rrd.update time, value
end

def graph
  RRD.graph 'trends.png', :title => 'Test', :width => 800, :height => 250, :color => ["FONT#000000", "BACK#FFFFFF"] do
    area 'trends.rrd', :requests => :average, :color => "#0066cc", :label => 'requests'
  end
end

def main(args)
  if args.length == 0
    puts "Usage: #{$0} <path> [path2] [...]"
    return 1
  end

  @@counter = 0

  EventMachine.run do
    EM.add_periodic_timer(300) do
      time = Time.now
      puts "#{time} #{@@counter}"

      update_rrd time, @@counter
      graph

      @@counter = 0
    end

    args.each do |path|
      EventMachine::file_tail(path, Reader)
    end
  end
end # def main

exit(main(ARGV))