Racket web server Racket

#lang racket/base
(require net/base64
         web-server/http
         web-server/servlet-env)

(define gif (base64-decode #"R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw=="))

(define (pixel req)
  (response/full 200 #"OK" (current-seconds) #"image/gif"
                 (list (header #"Cache-Control" #"no-store"))
                 (list gif)))

;; serve/servlet only dispatches requests whose path is exactly #:servlet-path.
(serve/servlet pixel
               #:port 8080
               #:listen-ip #f
               #:servlet-path "/pixel.gif"
               #:command-line? #t)