Add preferred self anti-affinity to kube-dns pods

This reverts commit 607c3d6967.

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"