I am using Manual SideCar for Istio and I want to use autoscale pods based on resource usage. I have specified resource usage in my yaml file.

        resources:
          requests:
            cpu: 250m    

But when I run command istioctl kube-inject -f file.yaml
I get

        ....
        name: istio-proxy
        resources: {}
        ....

It adds istio-proxy. But it doesn't add resources to the istio-proxy container. So I am unable to see targets of the pod using horizontal pod autoscaler. When I run
kubectl get hpa
I get

NAMESPACE          NAME              REFERENCE                           TARGETS           MINPODS   MAXPODS   REPLICAS   AGE
default            svc_autoscaler   Deployment/deploy              <unknown> / 70%             1         10        3          9m

And it doesn't get a value of target, so how can I specify a resources value at runtime