In the official Kubernetes documentation:
https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/
We can see the following:
This example requires a running Kubernetes cluster and kubectl, version 1.2 or later. Metrics server monitoring needs to be deployed in the cluster to provide metrics through the Metrics API. Horizontal Pod Autoscaler uses this API to collect metrics. To learn how to deploy the metrics-server, see the metrics-server documentation. To specify multiple resource metrics for a Horizontal Pod Autoscaler, you must have a Kubernetes cluster and kubectl at version 1.6 or later. To make use of custom metrics, your cluster must be able to communicate with the API server providing the custom Metrics API. Finally, to use metrics not related to any Kubernetes object you must have a Kubernetes cluster at version 1.10 or later, and you must be able to communicate with the API server that provides the external Metrics API. See the Horizontal Pod Autoscaler user guide for more details.
In order to verify I can "make use of custom metrics", I ran:
kubectl get metrics-server
And got the result: error: the server doesn't have a resource type "metrics-server"
May I ask what can I do to verify "Metrics server monitoring needs to be deployed in the cluster" please?
Thank you