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[Home](./index.md) &gt; [fastify-metrics](./fastify-metrics.md) &gt; [IRouteMetricsConfig](./fastify-metrics.iroutemetricsconfig.md) &gt; [customLabels](./fastify-metrics.iroutemetricsconfig.customlabels.md)

## IRouteMetricsConfig.customLabels property

Custom labels to add to metrics

**Signature:**

```typescript
customLabels?: Record<string, string | ((request: FastifyRequest, reply: FastifyReply) => string)>;
```

## Default Value

`undefined`

## Example

```ts
customLabels: {
 myLabel: 'my-value',
 myLabel2: (request, reply) => request.headers['x-my-header'],
}
```