loosen check rules for ingress creation

pkg/apis/networking/validation/validation.go

@@ -276,9 +276,9 @@ func ValidateIngressCreate(ingress *networking.Ingress) field.ErrorList {
 	}
 	allErrs = append(allErrs, validateIngress(ingress, opts)...)
 	annotationVal, annotationIsSet := ingress.Annotations[annotationIngressClass]
-	if annotationIsSet && ingress.Spec.IngressClassName != nil {
+	if annotationIsSet && ingress.Spec.IngressClassName != nil && annotationVal != *ingress.Spec.IngressClassName {
 		annotationPath := field.NewPath("annotations").Child(annotationIngressClass)
-		allErrs = append(allErrs, field.Invalid(annotationPath, annotationVal, "can not be set when the class field is also set"))
+		allErrs = append(allErrs, field.Invalid(annotationPath, annotationVal, "ingressClass annotation and IngressClassName should have the same value"))
 	}
 	return allErrs
 }

pkg/apis/networking/validation/validation_test.go

@@ -993,12 +993,19 @@ func TestValidateIngressCreate(t *testing.T) {
 			},
 			expectedErrs: field.ErrorList{},
 		},
-		"class field and annotation set": {
+		"class field and annotation set with same value": {
+			tweakIngress: func(ingress *networking.Ingress) {
+				ingress.Spec.IngressClassName = utilpointer.String("foo")
+				ingress.Annotations = map[string]string{annotationIngressClass: "foo"}
+			},
+			expectedErrs: field.ErrorList{},
+		},
+		"class field and annotation set with different value": {
 			tweakIngress: func(ingress *networking.Ingress) {
 				ingress.Spec.IngressClassName = utilpointer.String("bar")
 				ingress.Annotations = map[string]string{annotationIngressClass: "foo"}
 			},
-			expectedErrs: field.ErrorList{field.Invalid(field.NewPath("annotations").Child(annotationIngressClass), "foo", "can not be set when the class field is also set")},
+			expectedErrs: field.ErrorList{field.Invalid(field.NewPath("annotations").Child(annotationIngressClass), "foo", "ingressClass annotation and IngressClassName should have the same value")},
 		},
 		"valid regex path": {
 			tweakIngress: func(ingress *networking.Ingress) {

pkg/registry/networking/ingress/strategy.go

@@ -29,6 +29,10 @@ import (
 	"sigs.k8s.io/structured-merge-diff/v4/fieldpath"
 )
 
+const (
+	annotationIngressClass = "kubernetes.io/ingress.class"
+)
+
 // ingressStrategy implements verification logic for Replication Ingress.
 type ingressStrategy struct {
 	runtime.ObjectTyper
@@ -93,7 +97,15 @@ func (ingressStrategy) Validate(ctx context.Context, obj runtime.Object) field.E
 }
 
 // WarningsOnCreate returns warnings for the creation of the given object.
-func (ingressStrategy) WarningsOnCreate(ctx context.Context, obj runtime.Object) []string { return nil }
+func (ingressStrategy) WarningsOnCreate(ctx context.Context, obj runtime.Object) []string {
+	var warnings []string
+	ingress := obj.(*networking.Ingress)
+	_, annotationIsSet := ingress.Annotations[annotationIngressClass]
+	if annotationIsSet && ingress.Spec.IngressClassName != nil {
+		warnings = append(warnings, "ingressClass annotation and IngressClassName should not be set at the same time")
+	}
+	return warnings
+}
 
 // Canonicalize normalizes the object after validation.
 func (ingressStrategy) Canonicalize(obj runtime.Object) {

pkg/registry/networking/ingress/strategy_test.go

@@ -19,9 +19,11 @@ package ingress
 import (
 	"testing"
 
+	"github.com/google/go-cmp/cmp"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
 	"k8s.io/kubernetes/pkg/apis/networking"
+	utilpointer "k8s.io/utils/pointer"
 )
 
 func newIngress() networking.Ingress {
@@ -138,3 +140,68 @@ func TestIngressStatusStrategy(t *testing.T) {
 		t.Errorf("Unexpected error %v", errs)
 	}
 }
+
+func TestWarningsOnCreate(t *testing.T) {
+	ctx := genericapirequest.NewDefaultContext()
+	if !StatusStrategy.NamespaceScoped() {
+		t.Errorf("Ingress must be namespace scoped")
+	}
+	if StatusStrategy.AllowCreateOnUpdate() {
+		t.Errorf("Ingress should not allow create on update")
+	}
+
+	serviceBackend := &networking.IngressServiceBackend{
+		Name: "defaultbackend",
+		Port: networking.ServiceBackendPort{
+			Number: 80,
+		},
+	}
+	defaultBackend := networking.IngressBackend{
+		Service: serviceBackend,
+	}
+	baseIngress := &networking.Ingress{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:            "test123",
+			Namespace:       "test123",
+			ResourceVersion: "1234",
+		},
+		Spec: networking.IngressSpec{
+			DefaultBackend: &defaultBackend,
+			Rules:          []networking.IngressRule{},
+		},
+	}
+
+	testCases := map[string]struct {
+		tweakIngress     func(ingress *networking.Ingress)
+		expectedWarnings []string
+	}{
+		"ingressClass annotation and IngressClassName set": {
+			tweakIngress: func(ingress *networking.Ingress) {
+				ingress.Spec.IngressClassName = utilpointer.String("foo")
+				ingress.Annotations = map[string]string{annotationIngressClass: "foo"}
+			},
+			expectedWarnings: []string{"ingressClass annotation and IngressClassName should not be set at the same time"},
+		},
+		"ingressClass annotation set": {
+			tweakIngress: func(ingress *networking.Ingress) {
+				ingress.Annotations = map[string]string{annotationIngressClass: "foo"}
+			},
+		},
+		"IngressClassName set": {
+			tweakIngress: func(ingress *networking.Ingress) {
+				ingress.Spec.IngressClassName = utilpointer.String("foo")
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+		t.Run(name, func(t *testing.T) {
+			newIngress := baseIngress.DeepCopy()
+			testCase.tweakIngress(newIngress)
+			warnings := Strategy.WarningsOnCreate(ctx, newIngress)
+			if diff := cmp.Diff(warnings, testCase.expectedWarnings); diff != "" {
+				t.Errorf("warings does not match (-want,+got):\n%s", diff)
+			}
+		})
+	}
+}