Errors, Logging & Observability

Build Errors, Logging & Observability as a production boundary with validation, least privilege, structured errors and logs, health checks, timeouts, tests, and graceful shutdown. Never log secrets and keep the supported LTS patched.

Build a Complete Mental Model

Build Errors, Logging & Observability as a production boundary with validation, least privilege, structured errors and logs, health checks, timeouts, tests, and graceful shutdown. Never log secrets and keep the supported LTS patched.

Apply It in Production Node.js

Test an original Errors, Logging & Observability example with concurrent requests, malformed input, timeouts, cancellation, missing configuration, dependency failure, and shutdown. Check for blocking I/O, leaked handles, and unhandled rejections.

After This Lesson

• Explain the async boundary and resource owner
• Build an example with timeout and error handling
• Test one user-visible behavior

function logError(error, requestId) {
  console.error(JSON.stringify({ level:'error', requestId, name:error.name, message:error.message }));
}
process.on('unhandledRejection', error => { logError(error, 'process'); process.exitCode = 1; });

Failures produce searchable structured logs without dumping secrets.

Node.js API Documentation — Node.js