@vuedapt/logger

A production-ready logging library for Node.js with automatic HTTP request logging, color-coded log levels, and intelligent environment-based configuration. Features zero-configuration Express middleware for seamless HTTP logging and built-in production optimizations.

Changelog

See CHANGELOG.md.

Installation

npm install @vuedapt/logger

Usage

ES6 (ES Modules)

import logger from '@vuedapt/logger';

// Info logs
logger.info('Application started successfully');

// Warn logs
logger.warn('This is a warning message');

// Error logs
logger.error('An error occurred');

// Debug logs
logger.debug('Debug information');

// Express middleware (automatic HTTP logging for all requests)
import express from 'express';
const app = express();
app.use(logger.middleware());

ES5 (CommonJS)

const logger = require('@vuedapt/logger');

// Info logs
logger.info('Application started successfully');

// Warn logs
logger.warn('This is a warning message');

// Error logs
logger.error('An error occurred');

// Debug logs
logger.debug('Debug information');

// Express middleware (automatic HTTP logging for all requests)
const express = require('express');
const app = express();
app.use(logger.middleware());

Output Format

The default format is: YYYY-MM-DD HH:MM:SS [LEVEL] - Message

Default output (simplified):

• 2024-01-15 14:30:45 [INFO] - Application started successfully
• 2024-01-15 14:30:46 [WARN] - This is a warning message
• 2024-01-15 14:30:47 [ERROR] - An error occurred
• 2024-01-15 14:30:48 [DEBUG] - Debug information
• 2024-01-15 14:30:49 [HTTP] - GET /api/products HTTP/1.1 200

Customization

The logger can be customized using the configure() method:

ES6 (ES Modules)

import logger from '@vuedapt/logger';

// Enable file name and line number in logs
logger.configure({ showFileInfo: true });

// Disable stack traces for errors
logger.configure({ showStackTrace: false });

// Configure multiple options at once
logger.configure({
  showFileInfo: true,
  showStackTrace: true
});

ES5 (CommonJS)

const logger = require('@vuedapt/logger');

// Enable file name and line number in logs
logger.configure({ showFileInfo: true });

// Disable stack traces for errors
logger.configure({ showStackTrace: false });

// Configure multiple options at once
logger.configure({
  showFileInfo: true,
  showStackTrace: true
});

Configuration Options

• showFileInfo (default: false) - Show file name and line number in logs

  • When enabled: 2024-01-15 14:30:45 [INFO] - Message (app.js:42)
  • When disabled: 2024-01-15 14:30:45 [INFO] - Message

• showStackTrace (default: !isProduction()) - Show stack traces for ERROR logs

  • Automatically disabled in production for security
  • Can be manually enabled/disabled

Log Levels

• INFO - For informational messages
• WARN - For warning messages
• ERROR - For error messages
• DEBUG - For debug messages
• HTTP - Automatic HTTP request logging via Express middleware (method, URL, protocol, and status code)

HTTP Logging

HTTP requests are automatically logged when using the Express middleware. No configuration needed.

Status codes are color-coded:

• 2xx - Success
• 3xx - Redirect
• 4xx - Client error
• 5xx - Server error

Example output:

• 2024-01-15 14:30:45 [HTTP] - GET /api/users HTTP/1.1 200
• 2024-01-15 14:30:46 [HTTP] - POST /api/login HTTP/1.1 401
• 2024-01-15 14:30:47 [HTTP] - DELETE /api/resource/123 HTTP/2 500

Automatic extraction from request/response:

• Method: From req.method
• URL: From req.originalUrl or req.url
• Protocol: From req.protocol and req.httpVersion, or req.httpVersion alone
• Status Code: From res.statusCode

Express Middleware

Use the built-in middleware for automatic logging of all HTTP requests:

ES6 (ES Modules):

import express from 'express';
import logger from '@vuedapt/logger';

const app = express();

// Add logger middleware (logs all requests automatically)
app.use(logger.middleware());

app.get('/api/users', (req, res) => {
  res.json({ users: [] });
  // Request is automatically logged when response finishes
});

ES5 (CommonJS):

const express = require('express');
const logger = require('@vuedapt/logger');

const app = express();

// Add logger middleware (logs all requests automatically)
app.use(logger.middleware());

app.get('/api/users', (req, res) => {
  res.json({ users: [] });
  // Request is automatically logged when response finishes
});

The middleware automatically logs every HTTP request with all details extracted from the request/response objects.

Production Mode

The logger automatically adjusts its behavior based on the NODE_ENV environment variable:

When NODE_ENV=production:

• DEBUG logs are completely hidden - No debug output in production
• Stack traces are hidden - ERROR logs don't show full stack traces (security)
• File names and line numbers are hidden - No source location info (security)
• Cleaner logs - Reduced verbosity for better performance

When NODE_ENV is not production (development/staging):

• All log levels are shown (including DEBUG)
• Full stack traces for ERROR logs
• File names and line numbers included in all logs

Example

Development mode:

2024-01-15 14:30:45 [INFO] - Application started (app.js:42)
2024-01-15 14:30:46 [DEBUG] - Processing request (handler.js:15)
2024-01-15 14:30:47 [ERROR] - Database connection failed (db.js:23)
Error
    at Database.connect (db.js:23:10)
    at App.start (app.js:45:5)
    ...

Production mode:

2024-01-15 14:30:45 [INFO] - Application started
2024-01-15 14:30:47 [ERROR] - Database connection failed

Additional Production Recommendations

For production environments, consider:

1. Log aggregation - Use services like Loggly, Datadog, or CloudWatch
2. Structured logging - Consider JSON format for easier parsing (future enhancement)
3. Log rotation - Implement log rotation to manage disk space
4. Sensitive data - Never log passwords, tokens, or PII
5. Rate limiting - Consider rate limiting for high-volume applications
6. Error tracking - Integrate with error tracking services (Sentry, Rollbar)

License

MIT