***

title: "Instrument"
generated: true
---------------

<GenerationInfo sourceFile="packages/core/src/common/instrument-decorator.ts" sourceLine="46" packageName="@vendure/core" since="3.3.0" />

This decorator is used to apply instrumentation to a class. It is intended to be used in conjunction
with an [InstrumentationStrategy](/current/core/reference/typescript-api/telemetry/instrumentation-strategy#instrumentationstrategy) which defines how the instrumentation should be applied.

In order for the instrumentation to be applied, the `VENDURE_ENABLE_INSTRUMENTATION` environment
variable (exported from the `@vendure/core` package as `ENABLE_INSTRUMENTATION_ENV_VAR`) must be set to `true`.
This is done to avoid the overhead of instrumentation in environments where it is not needed.

:::warning
You should *not* decorate GraphQL resolvers & REST controllers with this decorator. Those will
already be instrumented, and adding the `@Instrument()` decorator will potentially
interfere with other NestJS decorators on your resolver methods.
:::

For more information on how instrumentation is used, see docs on the TelemetryPlugin.

*Example*

```ts
import { Instrument } from '@vendure/core';
import { Injectable } from '@nestjs/common';

@Injectable()
@Instrument() // [!code highlight]
export class MyService {

  // Calls to this method will be instrumented
  myMethod() {
    // ...
  }
}
```

```ts title="Signature"
function Instrument(): ClassDecorator
```