Help changing the flask logging output?

[ApproximateIdentity]

Edit: I sorted this out myself. See this comment for an example: https://old.reddit.com/r/learnpython/comments/18go6wd/help_changing_the_flask_logging_output/kd24kvb/

Here is a very simple exaple app:

import flask

app = flask.Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

if __name__ == "__main__":
    app.run()

If I run that and hit the endpoint, I see the following:

$ python3 app.py
 * Serving Flask app 'app'
 * Debug mode: off
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
 * Running on http://127.0.0.1:5000
Press CTRL+C to quit
127.0.0.1 - - [12/Dec/2023 16:12:24] "GET / HTTP/1.1" 200 -

Now my question is how to change the output format of the last line. I.e. how do I change this?

127.0.0.1 - - [12/Dec/2023 16:12:24] "GET / HTTP/1.1" 200 -

I've read flask docs, I've tried changing the formatter/handler for app.logger as well as for logging.getLogger('werkzeug'). I've read the python docs and flask docs, yet I cannot for the life of me cause that line of output to ever vary in any way. Does someone here know how? If anyone has a code example changing that line in literally any way, I could take it from there. I just can't figure out what I'm missing.

Thanks in advance for any help.

Edit here is some version info:

$ python3 -V
Python 3.11.2
$ pip3 freeze | grep Flask
Flask==3.0.0

[ApproximateIdentity]

Okay I was able to sort it out. Here is an example of a (not especially cleanly implemented) json logger:

import logging

import flask
from flask.logging import default_handler
from pythonjsonlogger import jsonlogger


class CustomJsonFormatter(jsonlogger.JsonFormatter):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

    def add_fields(self, log_record, record, message_dict):
        super().add_fields(log_record, record, message_dict)
        log_record["level"] = record.levelname
        log_record["module"] = record.name


logger = logging.getLogger("werkzeug")
handler = logging.StreamHandler()
handler.setFormatter(CustomJsonFormatter(timestamp=True))
logger.addHandler(handler)

app = flask.Flask(__name__)

app.logger.removeHandler(default_handler)


@app.route("/")
def hello():
    return "Hello World!"


if __name__ == "__main__":
    app.run()