A simple caching HTTP proxy in Python 3.

python3_caching_proxy.py

# A simple HTTP proxy which does caching of requests.
# Inspired by: https://gist.github.com/bxt/5195500
# but updated for Python 3 and some additional sanity improvements:
# - shutil is used to serve files in a streaming manner, so the entire data is not loaded into memory.
# - the http request is written to a temp file and renamed on success
# - forward headers

import http.server
import socketserver
import urllib.request
import shutil
import os
import hashlib
import sys

class CacheHandler(http.server.SimpleHTTPRequestHandler):
    def do_GET(self):
      m = hashlib.md5()
      m.update(self.path.encode("utf-8"))
      cache_filename = m.hexdigest() ".cached"

      if not os.path.exists(cache_filename):
          print("cache miss")
          with open(cache_filename + ".temp", "wb") as output:
            req = urllib.request.Request("http:/" + self.path)
            # copy request headers
            for k in self.headers:
                if k not in ["Host"]:
                    req.add_header(k, self.headers[k])
            try:
                resp = urllib.request.urlopen(req)
                shutil.copyfileobj(resp, output)
                os.rename(cache_filename + ".temp", cache_filename)
            except urllib.error.HTTPError as err:
                self.send_response(err.code)
                self.end_headers()
                return
      else:
          print("cache hit")
      
      with open(cache_filename, "rb") as cached:
          self.send_response(200)
          self.end_headers()
          shutil.copyfileobj(cached, self.wfile)

socketserver.TCPServer.allow_reuse_address = True
with socketserver.TCPServer(("", 8000), CacheHandler) as httpd:
    try:
        httpd.serve_forever()
    except KeyboardInterrupt:
        sys.exit(0)

Great job man !

https://gist.github.com/Jegeva/dafe74058ea30495c84c536a142a1144
added signal handling and tcpreuse to be easily spawed from another script in a subprocess without socket reuse problem