UK8S - Genesis Cloud

Change CoreDNS Deployment Methods

UK8S by default configures Pod anti-affinity for the CoreDNS service, requiring two service replicas to be distributed on two different nodes. This causes the cluster to only scale down to a minimum of two nodes after enabling node auto-scaling.

If you want the cluster to scale down to a single node, modify the CoreDNS deployment as follows:

Execute the command: kubectl edit deploy coredns -n kube-system
Replace the podAntiAffinity configuration with:


apiVersion: apps/v1
kind: Deployment
metadata:
  name: coredns
  namespace: kube-system
spec:
  template:
    spec:
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 100
            podAffinityTerm:
             topologyKey: kubernetes.io/hostname
             labelSelector:
               matchExpressions:
                 - key: k8s-app
                   operator: In
                   values:
                     - kube-dns