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# Python Logging > Configure structured logging for Python applications You are a Python logging specialist. The user wants to configure structured logging for Python applications with proper handlers, formatters, and log levels. ## What to check first - Verify Python version with `python --version` (logging module available in all modern versions) - Check if `logging` is already imported in your project with `grep -r "import logging" .` ## Steps 1. Import the `logging` module at the top of your application entry point 2. Create a logger instance using `logging.getLogger(__name__)` to get a module-specific logger 3. Set the root logger level using `logging.basicConfig()` or configure handlers explicitly 4. Create a `StreamHandler` for console output and a `FileHandler` for file persistence 5. Define a `Formatter` with structured format strings using LogRecord attributes like `%(asctime)s`, `%(name)s`, `%(levelname)s`, and `%(message)s` 6. Attach the formatter to each handler using `handler.setFormatter(formatter)` 7. Add handlers to your logger using `logger.addHandler(handler)` 8. Call logger methods (`logger.info()`, `logger.error()`, `logger.debug()`) throughout your code at appropriate severity levels ## Code ```python import logging import logging.handlers from datetime import datetime # Configure root logger def setup_logging(log_file='app.log', level=logging.INFO): """ Configure structured logging with console and file handlers. Args: log_file: Path to log file level: Logging level (DEBUG, INFO, WARNING, ERROR, CRITICAL) """ # Create logger logger = logging.getLogger() logger.setLevel(level) # Clear existing handlers to avoid duplicates logger.handlers.clear() # Define formatter with structured fields formatter = logging.Formatter( '%(asctime)s | %(name)s | %(levelname)-8s | %(message)s', datefmt='%Y-%m-%d %H:%M:%S' ) # Console handler (StreamHandler) console_handler = logging.StreamHandler() console_handler.setLevel(logging.DEBUG) console_handler.setFormatter(formatter) logger.addHandler(console_handler) # File handler (RotatingFileHandler for log rotation) file_handler = logging.handlers.RotatingFileHandler( log_file, maxBytes=10485760, # 10 MB backupCount=5 ) file_handler.setLevel(logging.DEBUG) file_handler.setFormatter(formatter) logger.addHandler(file_handler) return logger # Module-level logger logger = logging.getLogger(__name__) # Example usage in application if __name__ == '__main__': # Initialize logging at application startup setup_logging(log_file='myapp.log ``` *Note: this example was truncated in the source. See [the GitHub repo](https://github.com/Samarth0211/claude-skills-hub) for the latest full version.* ## Common Pitfalls - Treating this skill as a one-shot solution — most workflows need iteration and verification - Skipping the verification steps — you don't know it worked until you measure - Applying this skill without understanding the underlying problem — read the related docs first ## When NOT to Use This Skill - When a simpler manual approach would take less than 10 minutes - On critical production systems without testing in staging first - When you don't have permission or authorization to make these changes ## How to Verify It Worked - Run the verification steps documented above - Compare the output against your expected baseline - Check logs for any warnings or errors — silent failures are the worst kind ## Production Considerations - Test in staging before deploying to production - Have a rollback plan — every change should be reversible - Monitor the affected systems for at least 24 hours after the change --- *From [CLSkills.in](https://clskills.in/browse) — 2,300+ free Claude Code skills*