Next.js LogLayer Example

A minimal Next.js example showing how to integrate LogLayer with instrumentation.ts and route server-side console.* calls through a shared logger.

This repository is the companion example for my article:

Logging in Next.js with LogLayer: Instrumentation, Console Override, and Structured Logs

What it covers

• Shared LogLayer instance
• Server-side console.* interception with instrumentation.ts
• Structured errors and metadata
• Environment-based transports
• Direct LogLayer usage when structured context is needed

Run locally

npm install
npm run dev

Open http://localhost:3000 and check the terminal output.

Key files

• src/instrumentation.ts — hooks into Next.js startup and overrides server-side console methods
• src/lib/logger/index.ts — creates and configures the shared LogLayer instance
• src/lib/logger/utils/console.ts — maps console.* calls to LogLayer and handles errors and metadata

Example

Existing code can keep using console:

console.log("User created", { userId: "123" });

console.error(new Error("Something went wrong"));

On the server, those calls are routed through LogLayer and emitted as structured logs.

For code that needs richer context, LogLayer can also be used directly.

Notes

This example intentionally keeps the setup small and does not include dd-trace or other observability integrations.

The goal is to show the core logging setup before adding platform-specific concerns such as Datadog or OpenTelemetry.

Read the full article

For the reasoning behind the setup, runtime differences, console interception, and structured logging approach:

Read the full post on yurimutti.com →