async_request_logger.rb

class AsyncRequestLogger
  def initialize(app, logger = nil)
    @app = app
    @logger = logger || Logger.new(STDOUT)
  end
  
  def call(env)
    time = Time.now
    status, header, body = @app.call(env)
  ensure
    now = Time.now
    @logger << %{ [HTTP] %s - %s [%s] "%s %s%s %s" %s %0.4f\n} %
      [
       env['HTTP_X_FORWARDED_FOR'] || env["REMOTE_ADDR"] || "-",
       env["REMOTE_USER"] || "-",
       now.strftime("%d/%b/%Y %H:%M:%S"),
       env["REQUEST_METHOD"],
       env["PATH_INFO"],
       env["QUERY_STRING"].empty? ? "" : "?"+env["QUERY_STRING"],
       env["HTTP_VERSION"],
       status ? status.to_s[0..3] : "AIO",
       now - time
      ]
    [status, header, body]
  end
end


Thin::Server.start('0.0.0.0', 4567) do
  use AsyncRequestLogger
  run ProxyServer.new
end