How to implement logging in production Node.js applications

Short answer

Use a dedicated logging library like Winston or Pino instead of console.log to support log levels, structured formats, and multiple transports.

Steps

1. Install Winston: npm install winston.
2. Create a logger instance with transports for console and file.
3. Set log levels: error, warn, info, verbose, debug.
4. Use structured logging: logger.info('User login', { userId: 123 });.
5. Rotate log files to prevent disk space exhaustion.

Tips

• Use JSON formatting in production so log aggregation systems can parse fields automatically.
• Redact sensitive fields like passwords and tokens before logging.

Common issues

• Synchronous file logging with console.log can block the event loop under high load.
• Uncaught exceptions should be logged before the process exits; handle them with process.on('uncaughtException').