Configure three CoreDNS replicas on core nodes

k8s-ng/core-state/templates/applications.yaml

@@ -23,6 +23,9 @@ spec:
     syncOptions:
       - CreateNamespace=true
       - ServerSideApply=true
+      {{- if and (hasKey . "validate") (not .validate) }}
+      - Validate=false
+      {{- end }}
       {{- if .skipDryRunOnMissingResource }}
       - SkipDryRunOnMissingResource=true
       {{- end }}

k8s-ng/core-state/values.yaml

@@ -24,6 +24,11 @@ apps:
     path: k8s-ng/core/traefik-config
     namespace: kube-system
     wave: 1
+  - name: coredns-config
+    path: k8s-ng/core/coredns-config
+    namespace: kube-system
+    wave: 1
+    validate: false # partial Deployment: only the fields we manage
   - name: reloader
     path: k8s-ng/core/reloader
     namespace: reloader

k8s-ng/core/coredns-config/deployment.yaml

@@ -0,0 +1,22 @@
+# K3s owns the CoreDNS Deployment. Apply only the fields customized here so
+# upstream image, probes, Corefile mounts and topology spread stay intact.
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: coredns
+  namespace: kube-system
+  annotations:
+    argocd.argoproj.io/sync-options: Prune=false,Delete=false
+spec:
+  replicas: 3
+  template:
+    spec:
+      affinity:
+        nodeAffinity:
+          requiredDuringSchedulingIgnoredDuringExecution:
+            nodeSelectorTerms:
+              - matchExpressions:
+                  - key: homelab.hexor.cy/pool
+                    operator: In
+                    values:
+                      - core

k8s-ng/core/coredns-config/kustomization.yaml

@@ -0,0 +1,5 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - deployment.yaml