graphql_proxy_cache.py

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

class CacheHandler(http.server.CGIHTTPRequestHandler):
    def do_OPTIONS(self):
        self.send_response(200, "ok")
        self.send_header('Access-Control-Allow-Origin', '*')
        self.send_header('Access-Control-Allow-Methods', 'GET, POST, OPTIONS')
        self.send_header("Access-Control-Allow-Headers", "X-Requested-With")

    def do_POST(self):
      m = hashlib.md5()
      content_len = int(self.headers.get('Content-Length'))
      post_body = self.rfile.read(content_len)
      m.update(post_body)
      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://localhost:3000/" + 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, data=post_body)
                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, reading from " + cache_filename)

      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:
    print("Starting server at http://localhost:8000")
    try:
        httpd.serve_forever()
    except KeyboardInterrupt:
        sys.exit(0)