Kubernetes

Mandatory, for valid versions, 1.23 - 1.26

Network plug-ins - Tested with Calico

https://docs.projectcalico.org/getting-started/kubernetes/self-managed-onprem/onpremises

Firewall

Rules for accessing the pods externally 

Horizontal Pod Autoscaler

A metrics server is required when it comes to scaling. If you are planning to use the Horizontal Pod Autoscaler with custom metrics scaling, you will need to set up a Prometheus Adapter (see Setting up Prometheus(3.1)). For smaller and less complicated scaling such as using CPU based scaling, you can utilize a smaller metrics server such as: https://github.com/kubernetes-sigs/metrics-server.