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Python logging example

The native logging class in Python can be a little cumbersome and daunting to use. I've combined the use of ArgParse along with some simple use of logging as an example that solves a lot of problems I often want to solve:
I figure I'll refer to this example when I want to make use of logging in scripts in the future.

This example does the following:

  • Default logging level is to print warning, error, and fatal/critical error messages. Debugging and warning messages are not printed
  • Using one -v option prints all of the messages above including informational messages
  • Using two -v options prints all of the messages above including debugging messages
  • Using three or more -v options does not change the behavior from using two options. There is no error but there is no benefit to additional options either
  • You can specify an explicit log level and even reduce messages using -loglevel LEVEL where LEVEL must be one of:
    • DEBUG
    • INFO
    • WARNING
    • ERROR
    • CRITICAL
    The script support the use of FATAL which is just synonymous with CRITICAL.
    The -loglevel LEVEL and -v options are mutually exclusive.
  • There's no way to dispose of messages altogether through the options but it can be done by redirecting stderr to /dev/null
  • A custom format includes elements of the error that I want printed
  • Logging messages go to stderr

Usage

Here's the script in action: 

$ ./log_example
2019-01-18 08:26:31,929 WARNING ./log_example:16 This is a warning message
2019-01-18 08:26:31,929 ERROR ./log_example:17 This is an error message
2019-01-18 08:26:31,929 CRITICAL ./log_example:18 This is a fatal/critical message
$ ./log_example -v
2019-01-18 08:26:33,893 INFO ./log_example:15 This is an informational message
2019-01-18 08:26:33,893 WARNING ./log_example:16 This is a warning message
2019-01-18 08:26:33,893 ERROR ./log_example:17 This is an error message
2019-01-18 08:26:33,894 CRITICAL ./log_example:18 This is a fatal/critical message
$ ./log_example -vv
2019-01-18 08:26:35,603 DEBUG ./log_example:14 This is a debugging message
2019-01-18 08:26:35,603 INFO ./log_example:15 This is an informational message
2019-01-18 08:26:35,603 WARNING ./log_example:16 This is a warning message
2019-01-18 08:26:35,603 ERROR ./log_example:17 This is an error message
2019-01-18 08:26:35,603 CRITICAL ./log_example:18 This is a fatal/critical message
$ ./log_example -vvvvvvvvv
2019-01-18 08:26:38,438 DEBUG ./log_example:14 This is a debugging message
2019-01-18 08:26:38,438 INFO ./log_example:15 This is an informational message
2019-01-18 08:26:38,438 WARNING ./log_example:16 This is a warning message
2019-01-18 08:26:38,438 ERROR ./log_example:17 This is an error message
2019-01-18 08:26:38,438 CRITICAL ./log_example:18 This is a fatal/critical message
$

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