Click-log: Simple and beautiful logging for click applications¶
Licensed under the MIT, see
Assuming you have this Click application:
@click.command() def cli(): click.echo("Dividing by zero.") try: 1 / 0 except: click.echo("ERROR: Failed to divide by zero.")
Ignore the application’s core functionality for a moment. The much more pressing question here is: How do we add an option to not print anything on success? We could try this:
@click.command() @click.option('--quiet', default=False, is_flag=True) def cli(quiet): if not quiet: click.echo("Dividing by zero.") try: 1 / 0 except: click.echo("ERROR: Failed to divide by zero.")
Wrapping if-statements around each
echo-call is cumbersome though. And with
that, we discover logging:
import logging logger = logging.getLogger(__name__) # More setup for logging handlers here @click.command() @click.option('--quiet', default=False, is_flag=True) def cli(quiet): if quiet: logger.setLevel(logging.ERROR) else: logger.setLevel(logging.INFO) ...
Logging is a better solution, but partly because Python’s logging module aims to be so generic, it doesn’t come with sensible defaults for CLI applications. At some point you might also want to expose more logging levels through more options, at which point the boilerplate code grows even more.
This is where click-log comes in:
import logging logger = logging.getLogger(__name__) click_log.basic_config(logger) @click.command() @click_log.simple_verbosity_option(logger) def cli(): logger.info("Dividing by zero.") try: 1 / 0 except: logger.error("Failed to divide by zero.")
The output will look like this:
Dividing by zero. error: Failed to divide by zero.
error:-prefix will be red, unless the output is piped to another
simple_verbosity_option() decorator adds a
that takes a (case-insensitive) value of
CRITICAL, and calls
setLevel on the given logger
Make sure to define the simple_verbosity_option as early as possible. Otherwise logging setup will not be early enough for some of your other eager options.
simple_verbosity_option(logger=None, *names, **kwargs)¶
A decorator that adds a –verbosity, -v option to the decorated command.
Name can be configured through
*names. Keyword arguments are passed to the underlying