Observability 🔭

You can’t fix what you can’t see. Build observability into Next.js from day one.

Logging 📜

• Use structured loggers (pino, winston) in route handlers/server actions.
• Include request IDs, user IDs (if safe), and metadata for correlation.
• Ship logs to Datadog, Timber, ELK, or Vercel Log Drains.

Error Monitoring 🚨

• Integrate Sentry, Bugsnag, or Rollbar.
• Capture server component errors via error.tsx and componentDidCatch in client boundaries.
• Annotate releases for regression tracking.

Performance Monitoring ⚙️

• APM tools (Datadog APM, New Relic) track server latency, DB queries.
• Browser RUM (real user monitoring) captures Core Web Vitals.

Distributed Tracing 🧵

• Use OpenTelemetry instrumentation: instrumentation.ts file to wrap fetch, DB, queue calls.
• Propagate trace headers between middleware, route handlers, and external services.

Custom Metrics 📈

• Emit counters (cache hit rate, job failures) via StatsD, Prometheus, CloudWatch.
• Visualize dashboards (Grafana, Looker) for SLA adherence.

Debugging Prod 🕵️

• Enable feature-flagged debug routes that surface health info (auth restricted!).
• Capture heap snapshots/CPU profiles using Node inspector in staging before prod fixes.

Analogy: observability is mission control—logs are radio chatter, metrics are gauges, and traces are flight paths ensuring astronauts (users) arrive safely.