ec2-ping.rb

#!/usr/bin/env ruby

require 'nokogiri'
require 'net/http'
require 'uri'
require 'socket'

# First grab the reachability page and parse it
uri = URI.parse('http://ec2-reachability.amazonaws.com/')
r = Net::HTTP.get_response(uri)
doc = Nokogiri::HTML(r.body)

cur_region = nil
cur_ips = []
ips = {}

# A few heuristics are needed to get the data
# into a format we want
doc.css('table').each do |t|
  t.css('tr').each do |row|
    first = row.first_element_child
    if first['class'] == 'region-heading'
      if !cur_region.nil?
        ips[cur_region] = cur_ips
      end
      cur_region = first.text
      cur_ips = []
    else
      ip_elem = row.css('td')[2]
      cur_ips << ip_elem.text unless ip_elem.nil?
    end
  end
end

def time_tcp(host, port = 80)
  start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
  s = TCPSocket.new(host, port)
  stop = Process.clock_gettime(Process::CLOCK_MONOTONIC)
  s.close
  (stop - start)*1000
end

ips.each do |region, ip_list|
  times = []
  ip_list.each do |ip|
    times << time_tcp(ip)
  end
  puts "#{region} average: #{(times.inject(:+)/times.length).round(2)} ms"
end