Parse a Rails log file and send metrics to stathat

rails_log_stathat.rb

#!/usr/bin/env ruby

require 'net/http/persistent'
require 'uri'
require 'thread'

USAGE = <<EOS
Parse a Rails log file and send metrics to stathat

export EMAIL=email
export PREFIX=prefix
tail -f logfile | #{$0}
    - logfile is the path to the Rails logfile (example: log/production.log)
    - email is the email of the stathat account (mandatory)
    - prefix is the prefix for the stats name (optional, blank by default)

WARNING: need ruby 1.9 and the net-http-persistent gem
EOS

$verbose = false
$exit    = false
$uri     = URI "http://api.stathat.com/ez"
$queue   = Queue.new
$email   = ENV['EMAIL']
$prefix  = ENV['PREFIX']
if %w(-h --help).include?(ARGV[0]) || $email.nil?
  puts USAGE
  exit 0
end

module REGEXP
  PROCESSING = /^  Processing by (?<controller>\w+)#(?<action>\w+) as (?<format>\w+)$/
  COMPLETED  = /^Completed (?<code>\d+) .* in (?<time>\d+)/
  MONGODB    = /^MONGODB/
  RENDERED   = /^Rendered (?<template>\w+)/
  STARTED    = /^Started (?<verb>\w+) "(?<url>.+)" for (?<ip>[0-9.]+)/
end


def count(stat, value)
  stat = "#{$prefix} - #{stat}" if $prefix
  $queue << [stat, value]
end

def incr(stat)
  count stat, 1
end

def processing(line)
  data = line.match(REGEXP::PROCESSING)
  return unless data
  incr data['controller']
  incr "#{data['controller']}##{data['action']}"
  incr "as #{data['format']}"
end

def completed(line)
  data = line.match(REGEXP::COMPLETED)
  return unless data
  incr "Code #{data['code']}"
  count "Completed in", data['time'].to_i
end

def mongodb(line)
  incr "MongoDB" if line =~ REGEXP::MONGODB
end

def rendered(line)
  data = line.match(REGEXP::RENDERED)
  return unless data
  incr "Rendering total"
  incr "Rendering #{data['template']}"
end

def started(line)
  data = line.match(REGEXP::STARTED)
  return unless data
  incr "Requests"
  incr "#{data['verb']} requests"
  incr "URL #{data['url']}"
  incr "IP #{data['ip']}"
end

$threads = []
8.times do
  $threads << Thread.new do
    http = Net::HTTP::Persistent.new $0
    until $exit
      stat, count = *$queue.pop
      post = Net::HTTP::Post.new $uri.path
      post.set_form_data stat: stat, count: count, email: $email
      http.request $uri, post 
      puts "count #{stat} -> #{count}" if $verbose
    end
    http.shutdown
  end
end

ARGF.each do |line|
  case line[0]
  when ' ' then processing line
  when 'C' then completed  line
  when 'M' then mongodb    line
  when 'R' then rendered   line
  when 'S' then started    line
  end
end

Thread.pass until $queue.empty?
$exit = true
$threads.each {|t| t.join }