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click-loglevel provides a LogLevel parameter type for use in Click programs that wish to let the user set the logging level. It accepts all of the logging log level names (CRITICAL, ERROR, WARNING, INFO, DEBUG, and NOTSET, all case insensitive), and converts them into their corresponding numeric values. It also accepts integer values and leaves them as-is. Custom log levels are also supported.

Starting in version 0.4.0, shell completion of log level names (both built-in and custom) is also supported.

Installation

click-loglevel requires Python 3.7 or higher. Just use pip for Python 3 (You have pip, right?) to install it:

python3 -m pip install click-loglevel

Examples

myscript.py:

import logging
import click
from click_loglevel import LogLevel


@click.command()
@click.option(
    "-l",
    "--log-level",
    type=LogLevel(),
    default="INFO",
    help="Set logging level",
    show_default=True,
)
def main(log_level: int) -> None:
    logging.basicConfig(
        format="[%(levelname)-8s] %(message)s",
        level=log_level,
    )
    logging.log(log_level, "Log level set to %r", log_level)


if __name__ == "__main__":
    main()

Running myscript.py:

$ python3 myscript.py
[INFO    ] Log level set to 20
$ python3 myscript.py --log-level DEBUG
[DEBUG   ] Log level set to 10
$ python3 myscript.py --log-level error
[ERROR   ] Log level set to 40
$ python3 myscript.py --log-level 15
[Level 15] Log level set to 15

Script with custom log levels:

import logging
import click
from click_loglevel import LogLevel


logging.addLevelName(15, "VERBOSE")
logging.addLevelName(25, "NOTICE")


@click.command()
@click.option(
    "-l",
    "--log-level",
    type=LogLevel(extra=["VERBOSE", "NOTICE"]),
    default="INFO",
    help="Set logging level",
    show_default=True,
)
def main(log_level: int) -> None:
    logging.basicConfig(
        format="[%(levelname)-8s] %(message)s",
        level=log_level,
    )
    logging.log(log_level, "Log level set to %r", log_level)


if __name__ == "__main__":
    main()

API

The click_loglevel module contains a single class:

LogLevel

A subclass of click.ParamType that accepts the standard logging level names (case insensitive) and converts them to their corresponding numeric values. It also accepts integer values and leaves them as-is.

Custom log levels can be added by passing them as the extra argument to the constructor. extra can be either an iterable of level names (in which case the levels must have already been defined — typically at the module level — by calling logging.addLevelName()) or a mapping from level names to their corresponding values. All custom log levels will be recognized case insensitively; if two different level names differ only in case, the result is undefined.