Why isn't my Python logging setup working?

Question

My code looks like this

import logging formatter = logging.Formatter("{asctime} - {name} - {levelname} - {message}", "%d-%b-%y %H:%M", "{") def _add_handler(handler: logging.StreamHandler) -> logging.StreamHandler: handler.setFormatter(formatter) handler.setLevel(20) return handler logging.basicConfig( handlers={ _add_handler(logging.FileHandler("filename.log")), _add_handler(logging.StreamHandler()) }) logging.info("hello world")

What this is supposed to do is log "hello world" both to the console and a file named filename.log, with a severity of INFO, which is what the 20 in the setLevel method is for. However, nothing is being logged at all. Where have I gone wrong?

Vinay Sajip · Accepted Answer · 2021-07-25 05:28:59Z

1

You need to set the logging level for the logger as well. By default, it's set to logging.WARNING, so neither handler is seeing the message, let alone determining if it should be handled.

logging.basicConfig( level=logging.INFO, handlers={ _add_handler(logging.FileHandler("filename.log")), _add_handler(logging.StreamHandler()) })

edited Jul 25, 2021 at 5:28

Vinay Sajip

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answered Jul 23, 2021 at 16:33

chepner

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4 Comments

Cooper Harasyn Over a year ago

Beat me to it. I was about to answer the exact same thing. Please note the use of logging.INFO instead of the literal 20 - this should be changed in the handler as well.

chepner Over a year ago

Eh, I would prefer using the constants, but using an int literal isn't wrong.

Tahini245 Over a year ago

Thank you so much! I'm new to Stack Overflow and I've heard a lot of bad stuff about it, so I was lowkey scared about posting here

Cooper Harasyn Over a year ago

Glad to see you here despite what you heard, hope you had a good first experience! :)

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