Loguru

Language: Python

CLI/Utils

Loguru was created by Delgan in 2017 to offer a simpler, more intuitive logging experience than Python's built-in `logging` module. It aims to streamline logging setup and usage while providing advanced capabilities such as structured logging, colored outputs, and file rotation.

Loguru is a Python library that simplifies logging by providing an easy-to-use, flexible, and powerful logging system. It reduces boilerplate code and adds features like sink management, message formatting, and exception catching.

Installation

pip: pip install loguru
conda: conda install -c conda-forge loguru

Usage

Loguru allows you to log messages with various severity levels, format logs with colors, redirect logs to files, and catch exceptions automatically. It supports both synchronous and asynchronous applications and can be easily integrated into existing projects.

Simple logging

from loguru import logger

logger.info('This is an info message')
logger.warning('This is a warning')

Logs messages at different severity levels (info, warning) with minimal setup.

Logging to a file

from loguru import logger

logger.add('file.log')
logger.info('This message is saved to a file')

Redirects log output to a file, creating it automatically if it doesn’t exist.

Custom formatting

from loguru import logger

logger.add('file.log', format='{time} | {level} | {message}', level='INFO')
logger.info('Custom formatted log')

Uses a custom log format including time, severity level, and message.

Rotating log files

from loguru import logger

logger.add('file_{time}.log', rotation='1 MB')
logger.info('This log will rotate after reaching 1 MB')

Automatically rotates log files when they reach a specified size.

Catching exceptions

from loguru import logger

@logger.catch
def faulty():
    x = 1 / 0

faulty()

Automatically catches exceptions in functions, logs stack traces, and prevents application crash.

Multiple sinks

from loguru import logger

logger.add('file.log')
logger.add(sys.stderr, colorize=True, format='<green>{time}</green> | {level} | {message>')
logger.info('Logged to both file and console')

Logs messages to multiple outputs (file and console) with independent formatting.

Error Handling

FileNotFoundError: Ensure the specified log file path exists or use a valid path.
PermissionError: Check file permissions and ensure the application can write to the log file.

Best Practices

Use `logger.add()` to manage multiple log destinations and formats.

Use `@logger.catch` to simplify exception handling and logging.

Set appropriate log levels for different environments (DEBUG for development, WARNING/ERROR for production).

Rotate and compress log files to prevent storage issues.

Avoid excessive logging in performance-critical code sections.

Official DocsGithub