Create a logging system that captures application events, errors, and metrics with different severity levels, structured formatting, and log aggregation capabilities.

Project Checklist

• Implement different log levels (debug, info, warn, error)
• Create structured logging with metadata
• Add file-based log storage with rotation
• Implement request logging middleware
• Add error logging with stack traces
• Create log filtering and search capabilities

Bonus Project Checklist Items

• Integrate with log aggregation services (ELK, Splunk)
• Add log correlation IDs for request tracing
• Implement log sampling for high-volume applications
• Create log alerting for critical errors
• Add performance metrics logging
• Implement log compression and archival

Inspiration (Any companies/libraries similar)

• Winston
• Pino
• Datadog

Hint/Code snippet to start

const fs = require('fs');
const path = require('path');

class Logger {
  constructor(level = 'info') {
    this.levels = { debug: 0, info: 1, warn: 2, error: 3 };
    this.currentLevel = this.levels[level];
  }

  log(level, message, metadata = {}) {
    if (this.levels[level] >= this.currentLevel) {
      const logEntry = {
        timestamp: new Date().toISOString(),
        level,
        message,
        ...metadata
      };
      console.log(JSON.stringify(logEntry));
      this.writeToFile(logEntry);
    }
  }

  writeToFile(entry) {
    const logFile = path.join(__dirname, 'logs', 'app.log');
    fs.appendFileSync(logFile, JSON.stringify(entry) + '\n');
  }
}