Winston Has Free Production Logging for Node.js — Here's the Complete Setup Guide

Winston remains the most flexible Node.js logger. Here is how to set it up properly for production.

Quick Start

bun add winston

import winston from "winston";

const logger = winston.createLogger({
  level: "info",
  format: winston.format.combine(
    winston.format.timestamp(),
    winston.format.json()
  ),
  transports: [
    new winston.transports.File({ filename: "error.log", level: "error" }),
    new winston.transports.File({ filename: "combined.log" }),
  ],
});

if (process.env.NODE_ENV !== "production") {
  logger.add(new winston.transports.Console({
    format: winston.format.combine(
      winston.format.colorize(),
      winston.format.simple()
    ),
  }));
}

logger.info("Application started", { port: 3000 });
logger.error("Database connection failed", { host: "db.example.com", code: "ECONNREFUSED" });

Custom Formats

const customFormat = winston.format.combine(
  winston.format.timestamp({ format: "YYYY-MM-DD HH:mm:ss" }),
  winston.format.errors({ stack: true }),
  winston.format.printf(({ timestamp, level, message, stack, ...meta }) => {
    let log = `${timestamp} [${level}]: ${message}`;
    if (Object.keys(meta).length) log += ` ${JSON.stringify(meta)}`;
    if (stack) log += `\n${stack}`;
    return log;
  })
);

Log Rotation

bun add winston-daily-rotate-file

import DailyRotateFile from "winston-daily-rotate-file";

const transport = new DailyRotateFile({
  filename: "logs/app-%DATE%.log",
  datePattern: "YYYY-MM-DD",
  maxSize: "20m",
  maxFiles: "14d",
  zippedArchive: true,
});

const logger = winston.createLogger({
  transports: [transport],
});

Multiple Transports

const logger = winston.createLogger({
  transports: [
    // Console for dev
    new winston.transports.Console({ level: "debug" }),
    // File for all logs
    new winston.transports.File({ filename: "combined.log" }),
    // Separate file for errors
    new winston.transports.File({ filename: "error.log", level: "error" }),
    // HTTP transport for log aggregation
    new winston.transports.Http({
      host: "logs.example.com",
      port: 443,
      ssl: true,
      level: "warn",
    }),
  ],
});

Child Loggers (Scoped Context)

const requestLogger = logger.child({
  requestId: req.headers["x-request-id"],
  userId: req.user?.id,
});

requestLogger.info("Processing order");
requestLogger.info("Payment captured", { amount: 99.99 });
// Both logs include requestId and userId automatically

Express Middleware

import expressWinston from "express-winston";

app.use(expressWinston.logger({
  winstonInstance: logger,
  meta: true,
  msg: "HTTP {{req.method}} {{req.url}} {{res.statusCode}} {{res.responseTime}}ms",
  expressFormat: false,
}));

// Error logging
app.use(expressWinston.errorLogger({
  winstonInstance: logger,
}));

Production Best Practices

1. JSON format in production, pretty format in dev
2. Rotate logs daily with size limits
3. Separate error logs for quick debugging
4. Add request context (requestId, userId)
5. Never log sensitive data (passwords, tokens, PII)

// Filter sensitive fields
const sensitiveFilter = winston.format((info) => {
  if (info.password) info.password = "***";
  if (info.token) info.token = "***";
  if (info.creditCard) info.creditCard = "***";
  return info;
})();

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