How would you instrument a Next.js application for production diagnosis?

Combines server and client instrumentation, OpenTelemetry, post-response work, correlation, and privacy-aware signals.

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TL;DR

I initialize server telemetry in the root instrumentation.ts register function and load runtime-specific integrations conditionally. OpenTelemetry traces connect incoming route work, rendering, handlers, and downstream calls through a correlation context. Lightweight instrumentation-client.ts code captures navigation, errors, and user-centric performance, while sensitive values are excluded.

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instrumentation files, OpenTelemetry, client performance, after, tracing, correlation, deployment, and data policy.

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Core answer
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Overview
Useful observability connects browser experience, App Router work, downstream calls, and the deployed release without breaking the request path.
I initialize server telemetry in the root instrumentation.ts register function and load runtime-specific integrations conditionally. OpenTelemetry traces connect incoming route work, rendering, handlers, and downstream calls through a correlation context. Lightweight instrumentation-client.ts code captures navigation, errors, and user-centric performance, while sensitive values are excluded.
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Stronger answer
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The instrumentation module finishes setup before the server accepts requests, so I avoid slow global imports and verify both Node and Edge paths that the deployment uses. I record route patterns rather than high-cardinality raw URLs, attach release and environment, and propagate trace context to backend services. can schedule noncritical logging after the response, but it still runs within platform duration and may execute at build or revalidation time for static pages. It is not a durable queue for important business work.

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Details

Logging raw URLs, tokens, or form bodies as trace attributes.
Using after as guaranteed delivery for critical work.
Initializing an unsupported SDK in every runtime.

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How would you instrument a Next.js application for production diagnosis?

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