Understanding Next.js Instrumentation for Custom Logic at Startup

Instrumentation is a new feature introduced in Next.js 14 that allows you to run custom logic when your application starts.

The instrumentation.ts/js file lives at the root of your Next.js project and exposes a register() API, which will be called once when a new Next.js server instance is initiated.

Instrumentation is most often used to initiate logging or telemetry services.

In this example, the register() function initializes OpenTelemetry for the Next.js application.