Winston file logger

logger.js

import winston from 'winston';
import asyncLocalStorage from './request-context.js';

// Custom format to handle errors properly
const errorStackFormat = winston.format((info) => {
  if (info instanceof Error) {
    return Object.assign({}, info, {
      stack: info.stack,
      message: info.message,
    });
  }
  return info;
});

// Custom format to add request context
const addRequestContext = winston.format((info) => {
  const context = asyncLocalStorage.getStore();
  if (context?.uuid) {
    info.requestId = context.uuid;
  }
  return info;
});

// Winston Logger Configuration
const logger = winston.createLogger({
  level: process.env.LOG_LEVEL || 'info',
  format: winston.format.combine(
    errorStackFormat(),
    addRequestContext(),
    winston.format.timestamp({
      format: 'YYYY-MM-DD HH:mm:ss',
    }),
    winston.format.errors({ stack: true }),
    winston.format.splat(),
    winston.format.json(),
    winston.format.printf(({ timestamp, level, message, stack, ...metadata }) => {
      // Remove internal Winston properties
      delete metadata.splat;
      delete metadata.level;
      delete metadata.timestamp;

      // Create metadata string if there are properties
      const metaStr = Object.keys(metadata).length ? `\n${JSON.stringify(metadata, null, 2)}` : '';

      if (stack) {
        return `${timestamp} [${level.toUpperCase()}]: ${message}${metaStr}\n${stack}\n`;
      }
      return `${timestamp} [${level.toUpperCase()}]: ${message}${metaStr}\n`;
    })
  ),
  transports: [
    // File transport with rotation
    new winston.transports.File({
      filename: 'logs/error.log',
      level: 'error',
      maxsize: 5242880, // 5MB
      maxFiles: 5,
      tailable: true,
    }),
    new winston.transports.File({
      filename: 'logs/combined.log',
      maxsize: 5242880, // 5MB
      maxFiles: 5,
      tailable: true,
    }),
  ],
});

// Add console transport in non-production environments
if (process.env.NODE_ENV !== 'production') {
  logger.add(
    new winston.transports.Console({
      format: winston.format.combine(
        winston.format.colorize(),
        winston.format.printf(({ timestamp, level, message, stack, ...metadata }) => {
          // Remove internal Winston properties
          delete metadata.splat;
          delete metadata.level;
          delete metadata.timestamp;

          // Create metadata string if there are properties
          const metaStr = Object.keys(metadata).length ? ` ${JSON.stringify(metadata)}` : '';

          if (stack) {
            // Include stack trace if present
            return `${timestamp} [${level}]: ${message}${metaStr}\n${stack}`;
          }
          // Standard log format
          return `${timestamp} [${level}]: ${message}${metaStr}`;
        })
      ),
    })
  );
}

// Handling uncaught exceptions and unhandled rejections
logger.exceptions.handle(new winston.transports.File({ filename: 'logs/exceptions.log' }));

process.on('unhandledRejection', (error) => {
  logger.error('Unhandled Rejection:', error);
});

export default logger;