Loguru — Python Logging Made Stupidly Simple

What it is

Loguru is a Python logging library that replaces the standard library's logging module with a simpler API. One import gives you colorized terminal output, structured context binding, file rotation, and enhanced exception diagnosis. No handlers, no formatters, no configuration files.

Loguru is for Python developers who find the stdlib logging module tedious to set up. If you have ever written logging.basicConfig(level=logging.DEBUG, format='%(asctime)s...') and wished for something simpler, Loguru is the answer.

How it saves time or tokens

Python's stdlib logging requires creating loggers, handlers, formatters, and wiring them together. A basic setup that logs to both console and file with rotation takes 10-15 lines. Loguru does the same in 2 lines.

For debugging, Loguru's logger.exception() captures the full traceback with local variable values at each frame. Instead of reading a bare traceback and guessing variable state, you see exactly what each variable contained when the error occurred.

How to use

1. Install Loguru:

pip install loguru

1. Start logging immediately:

from loguru import logger

logger.info('Application started')
logger.warning('Disk usage at 85%')
logger.error('Failed to connect to database')

1. Add file logging with rotation:

logger.add('app.log', rotation='10 MB', retention='7 days', compression='gz')

Example

Structured logging with context and exception diagnosis:

from loguru import logger
import sys

# Configure structured JSON output for production
logger.remove()  # Remove default handler
logger.add(sys.stderr, format='{time} | {level} | {message}')
logger.add('app.log', serialize=True)  # JSON lines

# Bind context to all subsequent log calls
user_logger = logger.bind(user_id='u_12345', request_id='req_abc')
user_logger.info('Processing payment')

# Exception diagnosis with variable inspection
try:
    amount = 99.99
    currency = 'USD'
    result = process_charge(amount, currency)
except Exception:
    logger.exception('Payment processing failed')
    # Loguru shows: amount=99.99, currency='USD' in the traceback

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Common pitfalls

• Loguru replaces the default logger on import. If your project uses stdlib logging extensively with custom handlers, integrating Loguru requires care. Use logger.add(logging.Handler) to bridge the two systems.
• The serialize=True option outputs JSON lines, which is useful for log aggregation (ELK, Loki) but makes terminal output unreadable. Use it only for file or remote sinks.
• Loguru is thread-safe but not process-safe for file writes. In multiprocess applications, use the enqueue=True option to serialize writes through a queue.