Merge pull request #57683 from vainu-arto/kube-dns-anti-affinity

Automatic merge from submit-queue (batch tested with PRs 57683, 59116, 58728, 59140, 58976). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add self anti-affinity to kube-dns pods

Otherwise the "no single point of failure" setting doesn't actually work (a single node failure can still take down the entire cluster).

Fixes #40063

```release-note
Added anti-affinity to kube-dns pods
```

cluster/addons/dns/kube-dns.yaml.base

@@ -84,6 +84,17 @@ spec:
       annotations:
         scheduler.alpha.kubernetes.io/critical-pod: ''
     spec:
+      affinity:
+        podAntiAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+          - weight: 100
+            podAffinityTerm:
+              labelSelector:
+                matchExpressions:
+                  - key: k8s-app
+                    operator: In
+                    values: ["kube-dns"]
+              topologyKey: kubernetes.io/hostname
       tolerations:
       - key: "CriticalAddonsOnly"
         operator: "Exists"

cluster/addons/dns/kube-dns.yaml.in

@@ -84,6 +84,17 @@ spec:
       annotations:
         scheduler.alpha.kubernetes.io/critical-pod: ''
     spec:
+      affinity:
+        podAntiAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+          - weight: 100
+            podAffinityTerm:
+              labelSelector:
+                matchExpressions:
+                  - key: k8s-app
+                    operator: In
+                    values: ["kube-dns"]
+              topologyKey: kubernetes.io/hostname
       tolerations:
       - key: "CriticalAddonsOnly"
         operator: "Exists"

cluster/addons/dns/kube-dns.yaml.sed

@@ -84,6 +84,17 @@ spec:
       annotations:
         scheduler.alpha.kubernetes.io/critical-pod: ''
     spec:
+      affinity:
+        podAntiAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+          - weight: 100
+            podAffinityTerm:
+              labelSelector:
+                matchExpressions:
+                  - key: k8s-app
+                    operator: In
+                    values: ["kube-dns"]
+              topologyKey: kubernetes.io/hostname
       tolerations:
       - key: "CriticalAddonsOnly"
         operator: "Exists"