Small script to check the http status code of multiple app servers for a certain URL.

app_server_checker.rb

require 'open-uri'
require 'thread'
require 'benchmark'

# AppServerChecker checks the response for a specific URL on each app server.
# It does so by overwriting the Host header to the original hostname to trick
# the app server in serving the correct content. It also speeds up the check
# by creating a seperate thread for each request and outputs to stdout.
#
# Usage:
#   `AppServerChecker.new('htp://www.domain.tld').run!`
#
# Example output:
#   Checking 4 servers for http://www.springest.nl:
#   app01.springe.st: 200 OK 470ms
#   app02.springe.st: 200 OK 459ms
#   app03.springe.st: 200 OK 459ms
#   app04.springe.st: 200 OK 491ms
#
# The URL will default to www.springest.nl when none is given.
#
# You can run this script from the command line directly:
#   `ruby check_app_servers.rb http://www.springest.nl`
#
# Change the `SERVERS` constant if you want to add or remove servers.
# Change the `DEFAULT_URL` constant if you want to change the default url.
#
class AppServerChecker
  SERVERS = [
    'app01.springe.st',
    'app02.springe.st',
    'app03.springe.st',
    'app04.springe.st',
  ]

  DEFAULT_URL = 'http://www.springest.nl'

  attr_accessor :uri, :threads

  def initialize(url)
    url ||= DEFAULT_URL

    @uri = URI.parse(url)
    @threads = []
  end

  def run!
    puts "Checking #{SERVERS.size} servers for #{uri}:"

    SERVERS.each do |server|
      threads << Thread.new do
        status = ''
        benchmark = Benchmark.measure do
          begin
            open("http://#{server}#{uri.path}", 'Host' => uri.host) do |request|
              code, message = request.status
              status = "#{code} #{message}"
            end
          rescue OpenURI::HTTPError => e
            status = e
          end
        end

        puts "#{server}: #{status} #{(benchmark.real*1000).round}ms"
      end

      threads.each(&:join)
    end
  end
end

AppServerChecker.new(ARGV.first).run!