Kubernetes Autoscalling

Hi Team,

Need a help. I have installed docker and kubernetes in my mac and tried to do a basic autoscaling but im facing with Target unknown issue. please find the below exception im facing with.

NAME REFERENCE TARGETS MINPODS MAXPODS REPLICAS AGE
php-apache Deployment/php-apache /10% 1 10 0 4s

below the reference material i took and deployed:
https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/

I have also installed metric server as well.

Thanks.

Saravanan S