Setup server, Enhance Request Tracking, Error Handling, and Logging

[foyzulkarim]

Summary

We've established a modular Node.js server setup with Express.js as the web framework and Winston for logging.

Key features include a request ID middleware using AsyncLocalStorage for tracking requests across asynchronous operations, as well as centralized error handling for uncaught exceptions, unhandled rejections, and termination signals.

To promote maintainability, we employ a middleware-based architecture and hints of domain-driven design for structuring application logic.

Additionally, a custom AppError class normalizes error representation for consistent handling and potential integration with a monitoring system.

Details:

• Request ID Tracking:

  • Implemented a middleware using AsyncLocalStorage to generate and associate unique request IDs with each incoming request.
  • Request IDs are included in response headers and propagated throughout asynchronous operations.
  • Integrated requestId into the Winston logger for seamless correlation of log entries with requests.

• Centralized Error Handling:

  • Consolidated error handling logic for uncaught exceptions, unhandled promise rejections, and termination signals (SIGTERM, SIGINT).
  • Introduced a custom AppError class to normalize error representation.
  • Implemented graceful shutdown of the HTTP server when possible.
  • Integrated error metric firing (would send to a monitoring system in a production setting).

Files Modified:

• start.js: Updated to configure error handling and request ID middleware.
• server.js: Includes request-context middleware and error-handling middleware.
• app.js: Employs error handling middleware.
• request-context.js: New file containing the request ID middleware implementation.
• error-handling.js: New file encapsulating the error handling logic and AppError class.
• logger.js: Modified to incorporate the requestId into Winston log entries.
• Domain > product api: Sample API endpoint demonstrating usage of middleware and error handling setup.

Benefits

• Enhanced Observability: The addition of request IDs aids in debugging and tracing requests through the system, especially in distributed environments.
• Robust Error Handling: Centralized error handling ensures consistent processing of errors, promoting application stability.
• Improved Maintainability: Well-structured middleware and error handling implementation increase code readability and maintainability.