python3 http.server with authentication

auth.py

import http.server
import cgi
import base64
import json
import os
from urllib.parse import urlparse, parse_qs


class CustomServerHandler(http.server.SimpleHTTPRequestHandler):
    def do_HEAD(self):
        self.send_response(200)
        self.send_header('Content-type', 'application/json')
        self.end_headers()

    def do_AUTHHEAD(self):
        self.send_response(401)
        self.send_header('WWW-Authenticate', 'Basic realm="Demo Realm"')
        self.send_header('Content-type', 'application/json')
        self.end_headers()

    def do_GET(self):
        key = self.server.get_auth_key()

        ''' Present frontpage with user authentication. '''
        if self.headers.get('Authorization') == None:
            self.do_AUTHHEAD()
            super().do_GET()
            response = {'success': False, 'error': 'No auth header received'}

            self.wfile.write(bytes(json.dumps(response), 'utf-8'))

        elif self.headers.get('Authorization') == 'Basic ' + str(key):
            super().do_GET()
        else:
            self.do_AUTHHEAD()
            response = {'success': False, 'error': 'Invalid credentials'}
            self.wfile.write(bytes(json.dumps(response), 'utf-8'))

    def _parse_GET(self):
        getvars = parse_qs(urlparse(self.path).query)

        return getvars


class CustomHTTPServer(http.server.ThreadingHTTPServer):
    key = ''

    def __init__(self, address, handlerClass=CustomServerHandler):
        super().__init__(address, handlerClass)

    def set_auth(self, username, password):
        self.key = base64.b64encode(
            bytes('%s:%s' % (username, password), 'utf-8')
        ).decode('ascii')

    def get_auth_key(self):
        return self.key


if __name__ == '__main__':
    server = CustomHTTPServer(('', 5678))
    user = os.getenv('USERNAME', 'test')
    password = os.getenv('PASSWORD', 'test')
    server.set_auth(user, password)
    server.serve_forever()