Extended Middleware Error Logging Implementation

[ChaohuiLi0321]

🔒 Task: Extended Middleware Error Logging Implementation

📋 Overview

This PR implements comprehensive error logging middleware to improve backend visibility and debugging capabilities for the NutriHelp API. The implementation provides detailed error tracking, categorization, and real-time alerting for critical issues.

✨ What's New

🆕 Core Components Added

• services/errorLogService.js - Core error logging service with automatic categorization and sanitization
• middleware/errorLogger.js - Express middleware for error capture and performance monitoring
• Enhanced server.js - Integrated error logging pipeline with global exception handling

🗄️ Database Integration

• Utilizes existing error_logs table in Supabase
• Field mapping optimized for current database schema
• Automatic error categorization (critical, warning, info, minor)

🛡️ Security Features

• Sensitive data sanitization - Automatically redacts passwords, tokens, and API keys
• IP address tracking - Captures client information for security monitoring
• User session context - Links errors to specific users when available

🔧 Technical Implementation

Error Logging Service

// Automatic error categorization based on HTTP status and context
await errorLogService.logError({
  error: error,
  req: request,
  category: 'critical',  // Auto-categorized
  type: 'authentication'
});

Middleware Integration

// Response time monitoring + Error capture
app.use(responseTimeLogger);  // Before routes
app.use(errorLogger);         // After routes

Global Exception Handling

• Uncaught exceptions - Graceful handling with logging
• Unhandled promise rejections - Automatic capture and alerting
• Critical error alerts - Console-based alerting (extensible to Slack/email)

📊 Features & Benefits

Enhanced Debugging

• ✅ Detailed error context - Request headers, body, user session, system metrics
• ✅ Performance monitoring - Automatic slow request detection (>5s)
• ✅ Error classification - Automatic categorization for priority triage

Security & Compliance

• ✅ Data sanitization - Sensitive information automatically redacted
• ✅ User tracking - Links errors to specific user sessions
• ✅ Audit trail - Complete request/response context preservation

Operational Excellence

• ✅ Real-time alerting - Critical errors trigger immediate notifications
• ✅ Fallback logging - Console backup when database logging fails
• ✅ System health monitoring - Memory usage and CPU metrics captured

🧪 Testing & Validation

Automated Testing

• ✅ Error logging service tested - Basic and critical error scenarios
• ✅ Database integration verified - Successful writes to error_logs table
• ✅ Middleware integration confirmed - Server startup without errors

Manual Validation

# Test script execution successful
node scripts/testErrorLogging.js
✅ Basic error logging test passed
✅ Critical error logging test passed

📈 Database Records

The implementation successfully creates structured error logs in Supabase:

error_type: 'system'
error_message: 'Test error logging'
stack_trace: 'Error: Test error logging at testErrorLogging...'
endpoint: null
method: null
created_at: '2025-01-XX...'

🔗 Integration Points

Compatibility

• ✅ No breaking changes - Fully backward compatible with existing API
• ✅ Refresh Token system - Enhanced error logging for authentication failures
• ✅ Existing middleware - Works alongside rate limiting and security middleware

Future Extensions

• 🔄 Task 4 integration ready - Error logs will feed into security assessment reports
• 📧 Alert system extensible - Ready for Slack/email notification integration
• 📊 Dashboard preparation - Data structure optimized for future analytics

🎯 Sprint 2 Alignment

This implementation directly addresses Sprint 2: Monitoring, Logging & Scanning objectives:

• ✅ Enhanced middleware & audit logging
• ✅ Backend visibility improvements
• ✅ Foundation for automated testing integration
• ✅ Preparation for comprehensive security monitoring

🚀 Next Steps

1. Monitor production logs - Validate error patterns and categorization accuracy
2. Extend alerting - Integrate with Slack/email notification systems
3. Performance tuning - Optimize logging overhead for high-traffic scenarios
4. Task 4 integration - Leverage error logs in automated security assessments

---

Testing Instructions:

# 1. Start the server
npm start

# 2. Run error logging tests  
node scripts/testErrorLogging.js

# 3. Check Supabase error_logs table for new records
# 4. Verify server console shows error categorization

Database Requirements: ✅ Uses existing error_logs table - no schema changes needed

This implementation provides immediate value for debugging and incident response while establishing the foundation for comprehensive security monitoring in upcoming tasks.