Express Smart Logger Pro

Professional Express logging middleware that goes beyond basic logging.

What This Package Does

This isn't just a logger - it's a developer productivity tool that automatically:

• Logs every request with unique trace IDs
• Links related requests together with correlation IDs
• Tracks performance trends over time
• Captures full error context automatically
• Hides sensitive data with smart masking
• Provides performance insights and monitoring
• Adapts to development vs production environments

Why This Package is Different

Other logging packages:

• Only do basic request/response logging
• Require manual setup and configuration
• Don't provide performance insights
• Don't link related requests together
• Don't capture error context automatically

This package:

• Zero configuration - Just plug it in
• Request correlation - Automatically links related requests
• Performance insights - Tracks trends, not just individual requests
• Error context - Full debugging information automatically
• Production ready - Enterprise-grade monitoring capabilities
• Developer workflow - Perfect for debugging complex systems

Quick Start

Install

npm install express-smart-logger-pro

Use

const express = require('express');
const logger = require('express-smart-logger-pro');

const app = express();
app.use(logger()); // That's it!

app.get('/user', (req, res) => {
  res.json({ 
    name: 'John',
    password: 'secret123' // Will be hidden automatically
  });
});

All Features (Built-In, No Extra Setup)

🔍 Core Logging (Always Active)

• Trace ID - Every request gets unique ID like [TRACE-abc123]
• Request Details - Method, URL, status, duration
• Response Data - What your API returns (with sensitive data hidden)
• Performance - Request timing and slow request detection
• Environment - Colored logs in dev, JSON in production

🚀 Advanced Features (Always Active)

• Request Correlation - Automatically links related requests together
• Performance Insights - Tracks performance trends over time
• Error Context - Captures full request context when errors occur
• Smart Masking - Hides passwords, tokens, secrets automatically

📊 Performance Monitoring (Always Active)

• Trend Tracking - Average, Min, Max response times per endpoint
• Error Rates - Track error counts per endpoint
• Performance Degradation - Detect when endpoints slow down
• Historical Data - Performance data over time

🛡️ Security Features (Always Active)

• Auto-Masking - Hides sensitive fields automatically
• Smart Masking - Uses asterisks (********) instead of generic text
• Default Protection - Covers: password, token, secret, key, auth, authorization
• Custom Fields - Add your own sensitive fields to hide

Extra Features (Turn On When Needed)

// Basic usage - all advanced features work automatically
app.use(logger());

// Enhanced usage - enable additional logging
app.use(logger({
  logBody: true,                    // Log incoming request data
  logHeaders: true,                 // Log user-agent and IP address  
  logSize: true,                    // Log request/response sizes
  mask: ['creditCard', 'ssn'],      // Hide additional sensitive fields
  slowThreshold: 2000,              // Alert for requests slower than 2 seconds
  enableCorrelation: true,          // Link related requests together
  enablePerformanceInsights: true,  // Track performance trends over time
  enableErrorContext: true          // Capture full error context
}));

What You'll See

Development (Colored logs )

[TRACE-abc123] GET /user 200 (15ms)
Correlation ID: def456
Request Size: 45 bytes
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) Chrome/120.0.0.0
IP: 192.168.1.100
Request Body: {
  "email": "[email protected]",
  "password": "********"
}
Performance: Avg: 12ms, Min: 8ms, Max: 25ms
Response Size: 89 bytes
Response: {
  "name": "John",
  "password": "********"
}

Production (JSON logs )

{
  "traceId": "abc123",
  "correlationId": "def456",
  "timestamp": "2024-01-15T10:30:00.000Z",
  "method": "GET",
  "url": "/user",
  "status": 200,
  "duration": 15,
  "requestSize": 45,
  "responseSize": 89,
  "userAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) Chrome/120.0.0.0",
  "ip": "192.168.1.100",
  "requestBody": {
    "email": "[email protected]",
    "password": "********"
  },
  "performance": {
    "avgTime": 12,
    "minTime": 8,
    "maxTime": 25,
    "count": 150,
    "errorCount": 2
  },
  "response": {
    "name": "John",
    "password": "********"
  }
}

Advanced Developer Features

Request Correlation

Automatically links related requests together:

// All requests in a user session get the same correlation ID
// Perfect for debugging complex workflows and user journeys
// Track entire user sessions from login to logout

Performance Insights

Tracks performance trends over time:

// Shows: Average, Min, Max response times per endpoint
// Error rates and performance degradation alerts
// Historical performance data for optimization
// Identify which endpoints are slowing down over time

Enhanced Error Context

When errors occur, automatically captures:

// Full request context (headers, body, trace ID)
// Performance data at time of error
// Correlation with other requests in the session
// Perfect for debugging production issues

Performance Monitoring API

Access performance data programmatically:

const logger = require('express-smart-logger');

// Get performance stats for all endpoints
const stats = logger.getPerformanceStats();
console.log(stats);

// Clear performance data
logger.clearPerformanceStats();

// Get request correlation data
const correlations = logger.getRequestCorrelation();

What Gets Hidden Automatically

These fields are automatically hidden with asterisks:

• password → ********
• token → ****
• secret → ******
• key → ***
• auth → ****
• authorization → ************

Usage Examples

Basic Usage

app.use(logger());

With Request Body Logging

app.use(logger({
  logBody: true,
  logHeaders: true
}));

With Custom Masking

app.use(logger({
  mask: ['creditCard', 'ssn', 'apiKey']
}));

Full Enterprise Setup

app.use(logger({
  logBody: true,
  logHeaders: true,
  logSize: true,
  mask: ['creditCard', 'ssn', 'apiKey'],
  slowThreshold: 2000,
  enableCorrelation: true,
  enablePerformanceInsights: true,
  enableErrorContext: true
}));

Environment Detection

• Development: Colored console output with trace IDs and correlation IDs
• Production: Structured JSON logs for log aggregation and monitoring

Set NODE_ENV=production to enable production mode.

Use Cases

• API Development - Quick debugging with request correlation
• Production APIs - Enterprise-grade monitoring and insights
• Microservices - Track requests across service boundaries
• Complex Workflows - Debug user journeys with correlation IDs
• Performance Optimization - Identify slow endpoints and trends
• Error Investigation - Full context for production debugging

This Package Solves Real Problems

• "Why is my API slow?" → Performance insights show trends over time
• "Which requests are related?" → Correlation IDs link them automatically
• "What happened when this error occurred?" → Full error context captured
• "How is my API performing?" → Historical performance data available
• "Debug this user session" → Correlation IDs track entire workflows

License

MIT