How to Quickly Log into A File with Python

The aim of this page📝 is to define steps for a quick setup of the Python logging mechanism — for further discussion dive into the constantly awesome Real Python and its Logging in Python

1. DEFAULTS

• start with

import logging

• the most recognizable/typical feature for the language of logging are 5 severity levels

1. DEBUG
2. INFO
3. WARNING
4. ERROR
5. CRITICAL

• by default, the logging module logs the messages with a severity level of WARNING or above
• logger is the feature that does the writing and — importantly — it can/should have a custom name (not here)
• the default logger is called root
• the default syntax for the call is

<!-- DEFAULT CALL SYNTAX/EXAMPLE -->
logging.<SEVERITY LEVEL>('<MESSAGE>')
logging.critical('Server DOWN')

<!-- DEFAULT LOG SYNTAX/EXAMPLE -->
<SEVERITY>:<LOGGER>:<MESSAGE>
CRITICAL:root:Server DOWN

2. DEFINE

• since we are not using custom logger — use the basicConfig(**kwargs)
• if confused with **kwargs, read Use **kwargs To Accept An Arbitrary Number Of Keyword Arguments in Python | by Pavol Kutaj | Feb, 2022 | Medium
• 5 parameters are commonly passed into the basicConfig method

• In my case I am setting up the basicConfig in a dedicated module as follows

2.1. FORMAT DETAILS

• format parameter listed above can take a string with logrecord-attributes < logging < Logging facility for Python
• I am using this format

<!-- FORMAT ATTRIBUTES DEFINED -->
format='%(asctime)s | %(levelname)s | %(message)s'
<!-- LOG EXAMPLE -->
2022-03-10 14:53:37 | INFO | Create: New Doc...

3. CALL

• You call the defined logger when/where/as many times as you need it
• The utilization of f-strings — introduced in Python 3.6 — is optimal for message formatting
• I import the module with from logger import logging and call it as follows with the default call syntax

logging.<SEVERITY LEVEL>('<MESSAGE>')

• My example including the import of a dedicated logger module (used across my app)

• kb.log is populated with something like

2022-03-05 08:24:31 | INFO | Create: New Doc | 01.01 test-ignore | pavol kutaj | ZD URL not available

4. SHUTDOWN

• After the logging is done include

logging.shutdown()

• I need this because I am logging locally and I push logs to a GitHub repo during the execution.
• Without that, the file handler is opened and git does not detect the change to logs

Informs the logging system to perform an orderly shutdown by flushing and closing all handlers. This should be called at application exit and no further use of the logging system should be made after this call. When the logging module is imported, it registers this function as an exit handler (see atexit), so normally there’s no need to do that manually.

— from https://docs.python.org/3/library/logging.html#logging.shutdown

5. LINKS

• Logging in Python — Real Python
• format codes < datetime — Basic date and time types — Python 3.10.2 documentation
• 6 Python Logging Best Practices You Should Be Aware Of | Loggly