Instrumentation
Instrumentation is the process of using code to integrate monitoring and logging tools into your application. This allows you to track the performance and behavior of your application, and to debug issues in production.
Convention
To set up instrumentation, create instrumentation.ts|js
file in the root directory of your project (or inside the src
folder if using one).
Then, export a register
function in the file. This function will be called once when a new Next.js server instance is initiated.
For example, to use Next.js with OpenTelemetry and @vercel/otel:
import { registerOTel } from '@vercel/otel'
export function register() {
registerOTel('next-app')
}
See the Next.js with OpenTelemetry example for a complete implementation.
Good to know:
- The
instrumentation
file should be in the root of your project and not inside theapp
orpages
directory. If you're using thesrc
folder, then place the file insidesrc
alongsidepages
andapp
.- If you use the
pageExtensions
config option to add a suffix, you will also need to update theinstrumentation
filename to match.
Examples
Importing files with side effects
Sometimes, it may be useful to import a file in your code because of the side effects it will cause. For example, you might import a file that defines a set of global variables, but never explicitly use the imported file in your code. You would still have access to the global variables the package has declared.
We recommend importing files using JavaScript import
syntax within your register
function. The following example demonstrates a basic usage of import
in a register
function:
export async function register() {
await import('package-with-side-effect')
}
Good to know:
We recommend importing the file from within the
register
function, rather than at the top of the file. By doing this, you can colocate all of your side effects in one place in your code, and avoid any unintended consequences from importing globally at the top of the file.
Importing runtime-specific code
Next.js calls register
in all environments, so it's important to conditionally import any code that doesn't support specific runtimes (e.g. Edge or Node.js). You can use the NEXT_RUNTIME
environment variable to get the current environment:
export async function register() {
if (process.env.NEXT_RUNTIME === 'nodejs') {
await import('./instrumentation-node')
}
if (process.env.NEXT_RUNTIME === 'edge') {
await import('./instrumentation-edge')
}
}
Learn more about Instrumentation
Was this helpful?