logging.md

Logging

Logging is the logical next step when you realize the limitations of printing. Python includes a very useful logging module in the standard library so it's rather easy to get started. First make sure you know the basics. Now when you want to log some progress or program state in a module:

import logging

LOG = logging.getLogger(__name__)


def foo(bar):
    """My fancy function."""
    LOG.info("incrementing the input: %s", bar)
    return bar + 1

The not-so-intuitive part is that you need to configure the logging module to see any output from these calls. Luckily we can reduce the setup to a simple function call most of the time using the coloredlogs package. During e.g. your CLI initialization include:

import click
import coloredlogs
import logging

LOG = logging.getLogger(__name__)

@click.command()
@click.option('-l', '--log-level', default='INFO', help='Log message level to display')
def cli(log_level):
    """Base command line entry point."""
    coloredlogs.install(level=log_level)
	LOG.info("Running cli")
    # ... more code here