Starts a thread and serves the given data just once before closing the thread. Use with Selenium.

serve_once.py

import threading
from http.server import BaseHTTPRequestHandler, HTTPServer

def serve_once(data:str, port=8000, host="127.0.0.1"):
    """
    Serves the given data on the given port and host, then returns after
    responding to one request.
    
    This is a helpful way to send HTML to a browser being controled using Selenium.
    """
    class MyServer(BaseHTTPRequestHandler):
        def do_GET(self):
            self.send_response(200)
            self.end_headers()
            self.wfile.write(data.encode("utf-8"))

    httpd = None

    def run_localhost_server_in_thread():
        nonlocal httpd
        httpd = HTTPServer((host, port), MyServer)
        print("Serving once...")
        httpd.handle_request()
        print("Served once.")

    thread = threading.Thread(target=run_localhost_server_in_thread)
    thread.start()
    return thread