Add default namespace labels to all namespaces for selectors (#96968)

* namespace by name default labelling

Co-authored-by: Jordan Liggitt <jordan@liggitt.net>
Co-authored-by: Abhishek Raut <rauta@vmware.com>

* Make some logic improvement into default namespace label

* Fix unit tests

* minor change to trigger the CI

* Correct some tests and validation behaviors

* Add Canonicalize normalization and improve validation

* Remove label validation that should be dealt by strategy

* Update defaults_test.go
add fuzzer
ns spec

* remove the finalizer thingy

* Fix integration test

* Add namespace canonicalize unit test

* Improve validation code and code comments

* move validation of labels to validateupdate

* spacex will save us all

* add comment to testget

* readablility of canonicalize

* Added namespace finalize and status update validation

* comment about ungenerated names

* correcting a missing line on storage_test

* Update the namespace validation unit test

* Add more missing unit test changes

* Let's just blast the value. Also documenting the workflow here

* Remove unnecessary validations

Co-authored-by: Jordan Liggitt <jordan@liggitt.net>
Co-authored-by: Abhishek Raut <rauta@vmware.com>
Co-authored-by: Ricardo Pchevuzinske Katz <ricardo.katz@gmail.com>

pkg/apis/core/fuzzer/fuzzer.go

@@ -472,6 +472,16 @@ var Funcs = func(codecs runtimeserializer.CodecFactory) []interface{} {
 		func(s *core.NamespaceSpec, c fuzz.Continue) {
 			s.Finalizers = []core.FinalizerName{core.FinalizerKubernetes}
 		},
+		func(s *core.Namespace, c fuzz.Continue) {
+			c.FuzzNoCustom(s) // fuzz self without calling this function again
+			// Match name --> label defaulting
+			if len(s.Name) > 0 {
+				if s.Labels == nil {
+					s.Labels = map[string]string{}
+				}
+				s.Labels["kubernetes.io/metadata.name"] = s.Name
+			}
+		},
 		func(s *core.NamespaceStatus, c fuzz.Continue) {
 			s.Phase = core.NamespaceActive
 		},

pkg/apis/core/v1/defaults.go

@@ -323,6 +323,26 @@ func SetDefaults_HTTPGetAction(obj *v1.HTTPGetAction) {
 		obj.Scheme = v1.URISchemeHTTP
 	}
 }
+
+// SetDefaults_Namespace adds a default label for all namespaces
+func SetDefaults_Namespace(obj *v1.Namespace) {
+	// TODO, remove the feature gate in 1.22
+	// we can't SetDefaults for nameless namespaces (generateName).
+	// This code needs to be kept in sync with the implementation that exists
+	// in Namespace Canonicalize strategy (pkg/registry/core/namespace)
+
+	// note that this can result in many calls to feature enablement in some cases, but
+	// we assume that there's no real cost there.
+	if utilfeature.DefaultFeatureGate.Enabled(features.NamespaceDefaultLabelName) {
+		if len(obj.Name) > 0 {
+			if obj.Labels == nil {
+				obj.Labels = map[string]string{}
+			}
+			obj.Labels[v1.LabelMetadataName] = obj.Name
+		}
+	}
+}
+
 func SetDefaults_NamespaceStatus(obj *v1.NamespaceStatus) {
 	if obj.Phase == "" {
 		obj.Phase = v1.NamespaceActive

pkg/apis/core/v1/defaults_test.go

@@ -1416,6 +1416,40 @@ func TestSetDefaultNamespace(t *testing.T) {
 	}
 }
 
+func TestSetDefaultNamespaceLabels(t *testing.T) {
+	// Although this is defaulted to true, it's still worth to enable the feature gate during the test
+	defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.NamespaceDefaultLabelName, true)()
+
+	theNs := "default-ns-labels-are-great"
+	s := &v1.Namespace{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: theNs,
+		},
+	}
+	obj2 := roundTrip(t, runtime.Object(s))
+	s2 := obj2.(*v1.Namespace)
+
+	if s2.ObjectMeta.Labels[v1.LabelMetadataName] != theNs {
+		t.Errorf("Expected default namespace label value of %v, but got %v", theNs, s2.ObjectMeta.Labels[v1.LabelMetadataName])
+	}
+
+	// And let's disable the FG and check if it still defaults creating the labels
+	defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.NamespaceDefaultLabelName, false)()
+
+	theNs = "default-ns-labels-are-not-that-great"
+	s = &v1.Namespace{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: theNs,
+		},
+	}
+	obj2 = roundTrip(t, runtime.Object(s))
+	s2 = obj2.(*v1.Namespace)
+
+	if _, ok := s2.ObjectMeta.Labels[v1.LabelMetadataName]; ok {
+		t.Errorf("Default namespace shouldn't exist here, as the feature gate is disabled %v", s)
+	}
+}
+
 func TestSetDefaultPodSpecHostNetwork(t *testing.T) {
 	portNum := int32(8080)
 	s := v1.PodSpec{}

pkg/apis/core/v1/zz_generated.defaults.go

@@ -158,6 +158,7 @@ func SetObjectDefaults_LimitRangeList(in *v1.LimitRangeList) {
 }
 
 func SetObjectDefaults_Namespace(in *v1.Namespace) {
+	SetDefaults_Namespace(in)
 	SetDefaults_NamespaceStatus(&in.Status)
 }