Python module not producing logs after being imported

Question

I am building a tool with the following file structure:

+- my_tool
|   +- logs_dir
|   +- my_package
|   |   +- __init__.py  # main __init__
|   |   +- classes
|   |   |   +- __init__.py  # empty __init__
|   |   |   +- my_class.py
|   |   +- util
|   |   |   +- __init__.py  # empty __init__
|   |   |   +- _logger.py
|   |   +- tests
|   |   |   +- __init.py__  # empty __init__
|   |   |   +- test_my_class.py
|   |   +- config
|   |   |   +- logger.json
+- my_script.py

The python scripts contain the following code:

main __init__.py

from my_package.util import _logger

my_class.py

import logging

class TheClass():

    def __init__(self):
        
        self.log = logging.getLogger(__name__)
        self.log.info('this is a log output!')
    
    def a_method(self):
        return 'a string that is returned...'

_logger.py

import logging
import logging.config
from pathlib import Path
import json

logging_config_path = Path(__file__).parent.parent / 'config/logger.json'
with open(logging_config_path, 'r', encoding='utf-8') as config_file:
    LOGGING_CONFIG = json.load(config_file)
    
log_path = Path(__file__).parent.parent.parent

log_file = LOGGING_CONFIG['handlers']['file']['filename']
LOGGING_CONFIG['handlers']['file']['filename'] = log_path.join_path(log_file)

logging.config.dictConfig(LOGGING_CONFIG)

test_my_class.py

import pytest
from my_package.classes.my_class import TheClass

def test_the_class():
    the_class = TheClass()
    assert the_class.a_method() == 'a string that is returned...'

my_script.py

from my_tool.my_package.classes.my_class import TheClass

the_class = TheClass()
print(the_class.a_method())

logger.json

{
    "version": 1,
    "disable_existing_loggers": false,
    "formatters": {
        "standard": {
            "format": "%(asctime)s [%(levelname)s] %(name)|%(lineno)d:: %(message)s",
            "datefmt": "%Y-%m-%d %H:%M:%S"
        }
    },
    "handlers": {
        "default": {
            "formatter": "standard",
            "class": "logging.StreamHandler",
            "stream": "ext://sys.stdout"
        },
        "file": {
            "formatter": "standard",
            "class": "logging.FileHandler",
            "filename": "logs_dir/log.log"
        }
    },
    "loggers": {
        "": {
            "handlers": ["default"],
            "level": "WARNING",
            "propagate": false
        },
        "my_package": {
            "handlers": ["default", "file"],
            "level": "DEBUG", 
            "propagate": false
        }
    }
}

When I run test_my_class.py, I get logs in both the terminal and the log_dir directory. However, when I run my_script.py, no logs are produced at all.

I have tried changing "disable_existing_loggers" in the logger.json file but that does not change the behaviour.

How do I get the logs to output properly when I run my_script.py? Why is it currently not producing an output.

Answer 1

You do your logging setup in _logger.py.

When your run my_script.py the _logger.py is not executed. Because of that python's default settings for logging are relevant.

The default log-level is logging.WARNING. This means that logging.info() is lower then the default level not outputed somewhere.