Merge pull request #2542 from juanluisvaladas/fix-coredns-affinity

Avoid having multiple coredns replicas in the same node

inttest/basic/basic_test.go

@@ -99,6 +99,8 @@ func (s *BasicSuite) TestK0sGetsUp() {
 	}
 
 	s.verifyContainerdDefaultConfig()
+
+	s.verifyCoreDNSAntiAffinity(kc)
 }
 
 func (s *BasicSuite) checkCertPerms(node string) error {
@@ -203,6 +205,16 @@ func (s *BasicSuite) verifyContainerdDefaultConfig() {
 	}).URI(), parsedConfig.Plugins.CRI.SandboxImage)
 }
 
+func (s *BasicSuite) verifyCoreDNSAntiAffinity(kc *kubernetes.Clientset) {
+	opts := metav1.ListOptions{
+		LabelSelector: "k8s-app=kube-dns",
+	}
+	pods, err := kc.CoreV1().Pods("kube-system").List(s.Context(), opts)
+	s.NoError(err)
+	s.Equal(2, len(pods.Items))
+	s.NotEqual(pods.Items[0].Spec.NodeName, pods.Items[1].Spec.NodeName)
+}
+
 func TestBasicSuite(t *testing.T) {
 	s := BasicSuite{
 		common.FootlooseSuite{

pkg/component/controller/coredns.go

@@ -143,19 +143,17 @@ spec:
           operator: "Exists"
           effect: "NoSchedule"
       nodeSelector:
-        beta.kubernetes.io/os: linux
-      # Prefer running coredns replicas on different nodes
+        kubernetes.io/os: linux
+      # Require running coredns replicas on different nodes
       affinity:
         podAntiAffinity:
-          preferredDuringSchedulingIgnoredDuringExecution:
-          - weight: 100
-            podAffinityTerm:
-              topologyKey: "kubernetes.io/hostname"
-              labelSelector:
-                matchExpressions:
-                - key: k8s-app
-                  operator: In
-                  values: ['kube-dns']
+          requiredDuringSchedulingIgnoredDuringExecution:
+          - topologyKey: "kubernetes.io/hostname"
+            labelSelector:
+              matchExpressions:
+              - key: k8s-app
+                operator: In
+                values: ['kube-dns']
       containers:
       - name: coredns
         image: {{ .Image }}