instrumentation.js
The instrumentation.js|ts
file is used to integrate observability tools into your application, allowing you to track the performance and behavior, and to debug issues in production.
To use it, place the file in the root of your application or inside a src
folder if using one.
Exports
register
(optional)
The file exports a register
function that is called once when a new Next.js server instance is initiated. register
can be an async function.
import { registerOTel } from '@vercel/otel'
export function register() {
registerOTel('next-app')
}
onRequestError
(optional)
You can optionally export an onRequestError
function to track server errors to any custom observability provider.
- If you're running any async tasks in
onRequestError
, make sure they're awaited.onRequestError
will be triggered when the Next.js server captures the error. - The
error
instance might not be the original error instance thrown, as it may be processed by React if encountered during Server Components rendering. If this happens, you can usedigest
property on an error to identify the actual error type.
import { type Instrumentation } from 'next'
export const onRequestError: Instrumentation.onRequestError = async (
err,
request,
context
) => {
await fetch('https://.../report-error', {
method: 'POST',
body: JSON.stringify({
message: err.message,
request,
context,
}),
headers: {
'Content-Type': 'application/json',
},
})
}
Parameters
The function accepts three parameters: error
, request
, and context
.
export function onRequestError(
error: { digest: string } & Error,
request: {
path: string // resource path, e.g. /blog?name=foo
method: string // request method. e.g. GET, POST, etc
headers: { [key: string]: string }
},
context: {
routerKind: 'Pages Router' | 'App Router' // the router type
routePath: string // the route file path, e.g. /app/blog/[dynamic]
routeType: 'render' | 'route' | 'action' | 'middleware' // the context in which the error occurred
renderSource:
| 'react-server-components'
| 'react-server-components-payload'
| 'server-rendering'
revalidateReason: 'on-demand' | 'stale' | undefined // undefined is a normal request without revalidation
renderType: 'dynamic' | 'dynamic-resume' // 'dynamic-resume' for PPR
}
): void | Promise<void>
error
: The caught error itself (type is alwaysError
), and adigest
property which is the unique ID of the error.request
: Read-only request information associated with the error.context
: The context in which the error occurred. This can be the type of router (App or Pages Router), and/or (Server Components ('render'
), Route Handlers ('route'
), Server Actions ('action'
), or Middleware ('middleware'
)).
Specifying the runtime
The instrumentation.js
file works in both the Node.js and Edge runtime, however, you can use process.env.NEXT_RUNTIME
to target a specific runtime.
export function register() {
if (process.env.NEXT_RUNTIME === 'edge') {
return require('./register.edge')
} else {
return require('./register.node')
}
}
export function onRequestError() {
if (process.env.NEXT_RUNTIME === 'edge') {
return require('./on-request-error.edge')
} else {
return require('./on-request-error.node')
}
}
Version History
Version | Changes |
---|---|
v15.0.0-RC | onRequestError introduced, instrumentation stable |
v14.0.4 | Turbopack support for instrumentation |
v13.2.0 | instrumentation introduced as an experimental feature |
Learn more about Instrumentation
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