Merge pull request #2725 from gab-satchi/2723-unset-dns

🐛 Allows dns image tag to be unset

Author: k8s-ci-robot

controlplane/kubeadm/api/v1alpha3/kubeadm_control_plane_webhook.go

@@ -266,12 +266,13 @@ func (in *KubeadmControlPlane) validateCoreDNSVersion(prev *KubeadmControlPlane)
 	if in.Spec.KubeadmConfigSpec.ClusterConfiguration == nil || prev.Spec.KubeadmConfigSpec.ClusterConfiguration == nil {
 		return allErrs
 	}
-	if prev.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS.ImageTag == "" {
+	//return if either current or target versions is empty
+	if prev.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS.ImageTag == "" || in.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS.ImageTag == "" {
 		return allErrs
 	}
-	dns := &in.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS
+	targetDNS := &in.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS
 	//return if the type is anything other than empty (default), or CoreDNS.
-	if dns.Type != "" && dns.Type != kubeadmv1.CoreDNS {
+	if targetDNS.Type != "" && targetDNS.Type != kubeadmv1.CoreDNS {
 		return allErrs
 	}
 
@@ -286,13 +287,13 @@ func (in *KubeadmControlPlane) validateCoreDNSVersion(prev *KubeadmControlPlane)
 		return allErrs
 	}
 
-	toVersion, err := util.ParseMajorMinorPatch(dns.ImageTag)
+	toVersion, err := util.ParseMajorMinorPatch(targetDNS.ImageTag)
 	if err != nil {
 		allErrs = append(allErrs,
 			field.Invalid(
 				field.NewPath("spec", "kubeadmConfigSpec", "clusterConfiguration", "dns", "imageTag"),
-				dns.ImageTag,
-				fmt.Sprintf("failed to parse CoreDNS target version: %v", dns.ImageTag),
+				targetDNS.ImageTag,
+				fmt.Sprintf("failed to parse CoreDNS target version: %v", targetDNS.ImageTag),
 			),
 		)
 		return allErrs

controlplane/kubeadm/api/v1alpha3/kubeadm_control_plane_webhook_test.go

@@ -309,6 +309,14 @@ func TestKubeadmControlPlaneValidateUpdate(t *testing.T) {
 		},
 	}
 
+	unsetCoreDNSToVersion := dns.DeepCopy()
+	unsetCoreDNSToVersion.Spec.KubeadmConfigSpec.ClusterConfiguration.DNS = kubeadmv1beta1.DNS{
+		ImageMeta: kubeadmv1beta1.ImageMeta{
+			ImageRepository: "",
+			ImageTag:        "",
+		},
+	}
+
 	certificatesDir := before.DeepCopy()
 	certificatesDir.Spec.KubeadmConfigSpec.ClusterConfiguration.CertificatesDir = "a new certificates directory"
 
@@ -505,6 +513,12 @@ func TestKubeadmControlPlaneValidateUpdate(t *testing.T) {
 			before:    dns,
 			kcp:       validCoreDNSCustomToVersion,
 		},
+		{
+			name:      "should succeed when CoreDNS ImageTag is unset",
+			expectErr: false,
+			before:    dns,
+			kcp:       unsetCoreDNSToVersion,
+		},
 		{
 			name:      "should succeed when using an valid DNS build",
 			expectErr: false,