Munin script written in Ruby to get more details about a single HTTP connection, namely: DNS lookup time, connect time, send request time, wait for first byte of response and response time.

http_responsetime_detailed.rb

#!/usr/bin/env ruby

require 'uri'
require 'socket'

if ARGV[0] and ( ARGV[0] == "-h" or ARGV[0] == "--help" )
  puts "#{$0} [-h|--help] [config]"
  puts "Munin plugin to measure individual HTTP timings"
  puts " --help,-h  Show this help"
  puts "    config  Prints the configuration for munin"
  puts ""
  puts "Environment variables:"
  puts " URL          - URL to connect to"
  puts " HTTP_HEADER  - Custom HTTP Header(s) to append"
  puts " graph_title  - Title for the munin graph"
  puts ""
  puts "All values are reported in ms"
  puts ""
  puts "Written by Markus Fischer <markus@fischer.name>"
  exit 0
end

graph_title = ENV['graph_title'] || "HTTP timings"

if ARGV[0] and ARGV[0] == "config"
  puts <<EOT
graph_title #{graph_title}
graph_vlabel Time [ms]
graph_args --base 1000
graph_scale no
graph_category HTTPng
dns.label DNS
dns.draw AREA
connect.label Connect
connect.draw STACK
header_sent.label Header sent
header_sent.draw STACK
waiting.label Waiting
waiting.draw STACK
received.label Received
received.draw STACK
EOT
  exit 0
end

def diff_time_ms(a,b)
  ((a - b) * 1000).to_i
end

HTTP_LE = "\r\n"

uri = URI.parse ENV['URL']

request_a = [
  "GET / HTTP/1.1",
  "Host: #{uri.host}",
  "Connection: Close"
]

if ENV['HTTP_HEADER']
  request_a << ENV['HTTP_HEADER']
end

request = request_a.join(HTTP_LE) + HTTP_LE + HTTP_LE

timings = {}

timings[:start] = Time.now

hosts = TCPSocket.gethostbyname uri.host

timings[:dns] = Time.now

socket = TCPSocket.new hosts[3], uri.port

timings[:connected] = Time.now

socket.print request

timings[:sent_request] = Time.now

response = socket.recv 1

# So we know how long it took to receive the first byte
timings[:response_started] = Time.now

while rec = socket.recv(4096)
  response += rec
  break if rec.length == 0
end

timings[:response_finished] = Time.now


data = {}
data[:dns] = diff_time_ms(timings[:dns], timings[:start])
data[:connect] = diff_time_ms(timings[:connected], timings[:dns])
data[:header_sent] = diff_time_ms(timings[:sent_request], timings[:connected])
data[:waiting] = diff_time_ms(timings[:response_started], timings[:sent_request])
data[:received] = diff_time_ms(timings[:response_finished], timings[:response_started])

data.each do |k,v|
  puts "#{k}.value #{v}"
end