Custom Rack Stack that Dumps Request Headers

gistfile1.rb

# Taken from: http://stackoverflow.com/a/6318491

require 'rack'

app = Proc.new do |env|
  headers = env.select {|k,v| k.start_with? 'HTTP_'}
    .collect {|pair| [pair[0].sub(/^HTTP_/, ''), pair[1]]}
    .collect {|pair| pair.join(": ") << "<br>"}
    .sort
  [200, {'Content-Type' => 'text/html'}, headers]
end

Rack::Server.start :app => app, :Port => 8080