What is the need for a Metrics Server ?
If no Metrics Server is running on a Kubernetes cluster, the application "instances" (aka Pods) will report errors when it will try to show metrics (RAM, CPU etc) with the command epinio app show
Install a Metrics Server
Please read and follow the instructions for installing a Metrics Server. You will get the information about the requirements, the various installation methods (plain yaml, helm chart, etc), and guidance for additional configurations such as high availability and security.
As an example, here is the command to install a Metrics Server:
kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml
This installation method should be used only for simple environments.