I found another (simpler) solution here: http://www.piware.de/2011/01/creating-an-https-server-in-python/

This is my working porting to python3:

from http.server import HTTPServer,SimpleHTTPRequestHandler
from socketserver import BaseServer
import ssl

httpd = HTTPServer(('localhost', 1443), SimpleHTTPRequestHandler)
httpd.socket = ssl.wrap_socket (httpd.socket, certfile='certificate.pem', server_side=True)
httpd.serve_forever()

Per the mysql-connector-python package bug report linked by steeldriver, the cause of the issue appears to be that Python 3.12 removed ssl.wrap_socket (it had been marked deprecated since Python 3.7), but the version of the Python mysql.connector package provided by Ubuntu's python3-mysql.connector package is an old version incompatible with Python 3.12 that expects ssl.wrap_socket to still exist.

From the upstream mysql-connector-python repo, it appears that support for Python 3.12 was first introduced in version v8.2.0. But, in Ubuntu 24.04 LTS, if we apt install python3-msql.connector, inspecting /usr/lib/python3/dist-packages/mysql/connector/version.py and /usr/lib/python3/dist-packages/mysql/connector/network.py shows that it is version v8.0.15, which is not documented as supporting Python 3.12, and attempts to call ssl.wrap_socket are still present inside network.py. So we expect that not to work.

Here's an example following Steeldriver's suggested workaround, avoiding use of the globally installed mysql.connector package provided by ubuntu's python3-mysql.connector package that is incompatible with python3.12, and instead installing a newer version of that package from pypi to an isolated python virtual environment:

$ cat issue.sh

#! /usr/bin/env bash
set -uxo pipefail

python3 -m venv venv
source venv/bin/activate
python3 -m pip install --upgrade mysql-connector-python
python3 test.py

$ cat test.py
import mysql.connector
db = mysql.connector.connect(host="localhost", user="ray", password="...")
print(db)
exit(0)

Run it with chmod +x ./issue.sh && ./issue.sh.

When I run this, it installs version 9.5.0 of the msql-connector-python package.

There is no difference.

socket.ssl() is a deprecated method that calls socket.wrap_socket() underneath, just does some checking whether python has been compiled with SSL support (which import ssl will do for you in any case).

def ssl(sock, keyfile=None, certfile=None):
    # we do an internal import here because the ssl
    # module imports the socket module
    import ssl as _realssl
    warnings.warn("socket.ssl() is deprecated.  Use ssl.wrap_socket() instead.",
                  DeprecationWarning, stacklevel=2)
    return _realssl.sslwrap_simple(sock, keyfile, certfile)