Add validation for revisionHistoryLimit in sts to prevent negative value (kubernetes#129017)

* Add validation for revisionHistoryLimit in sts to prevent negative value

* Add unit tests to verify warning messages

Author: ardaguclu

pkg/apis/apps/validation/validation.go

@@ -182,15 +182,16 @@ func ValidateStatefulSetUpdate(statefulSet, oldStatefulSet *apps.StatefulSet, op
 	// statefulset updates aren't super common and general updates are likely to be touching spec, so we'll do this
 	// deep copy right away.  This avoids mutating our inputs
 	newStatefulSetClone := statefulSet.DeepCopy()
-	newStatefulSetClone.Spec.Replicas = oldStatefulSet.Spec.Replicas               // +k8s:verify-mutation:reason=clone
-	newStatefulSetClone.Spec.Template = oldStatefulSet.Spec.Template               // +k8s:verify-mutation:reason=clone
-	newStatefulSetClone.Spec.UpdateStrategy = oldStatefulSet.Spec.UpdateStrategy   // +k8s:verify-mutation:reason=clone
-	newStatefulSetClone.Spec.MinReadySeconds = oldStatefulSet.Spec.MinReadySeconds // +k8s:verify-mutation:reason=clone
-	newStatefulSetClone.Spec.Ordinals = oldStatefulSet.Spec.Ordinals               // +k8s:verify-mutation:reason=clone
+	newStatefulSetClone.Spec.Replicas = oldStatefulSet.Spec.Replicas                         // +k8s:verify-mutation:reason=clone
+	newStatefulSetClone.Spec.Template = oldStatefulSet.Spec.Template                         // +k8s:verify-mutation:reason=clone
+	newStatefulSetClone.Spec.UpdateStrategy = oldStatefulSet.Spec.UpdateStrategy             // +k8s:verify-mutation:reason=clone
+	newStatefulSetClone.Spec.MinReadySeconds = oldStatefulSet.Spec.MinReadySeconds           // +k8s:verify-mutation:reason=clone
+	newStatefulSetClone.Spec.Ordinals = oldStatefulSet.Spec.Ordinals                         // +k8s:verify-mutation:reason=clone
+	newStatefulSetClone.Spec.RevisionHistoryLimit = oldStatefulSet.Spec.RevisionHistoryLimit // +k8s:verify-mutation:reason=clone
 
 	newStatefulSetClone.Spec.PersistentVolumeClaimRetentionPolicy = oldStatefulSet.Spec.PersistentVolumeClaimRetentionPolicy // +k8s:verify-mutation:reason=clone
 	if !apiequality.Semantic.DeepEqual(newStatefulSetClone.Spec, oldStatefulSet.Spec) {
-		allErrs = append(allErrs, field.Forbidden(field.NewPath("spec"), "updates to statefulset spec for fields other than 'replicas', 'ordinals', 'template', 'updateStrategy', 'persistentVolumeClaimRetentionPolicy' and 'minReadySeconds' are forbidden"))
+		allErrs = append(allErrs, field.Forbidden(field.NewPath("spec"), "updates to statefulset spec for fields other than 'replicas', 'ordinals', 'template', 'updateStrategy', 'revisionHistoryLimit', 'persistentVolumeClaimRetentionPolicy' and 'minReadySeconds' are forbidden"))
 	}
 
 	return allErrs

pkg/registry/apps/statefulset/strategy.go

@@ -150,6 +150,10 @@ func (statefulSetStrategy) WarningsOnCreate(ctx context.Context, obj runtime.Obj
 	for i, pvc := range newStatefulSet.Spec.VolumeClaimTemplates {
 		warnings = append(warnings, pvcutil.GetWarningsForPersistentVolumeClaimSpec(field.NewPath("spec", "volumeClaimTemplates").Index(i), pvc.Spec)...)
 	}
+
+	if newStatefulSet.Spec.RevisionHistoryLimit != nil && *newStatefulSet.Spec.RevisionHistoryLimit < 0 {
+		warnings = append(warnings, "spec.revisionHistoryLimit: a negative value retains all historical revisions; a value >= 0 is recommended")
+	}
 	return warnings
 }
 
@@ -182,6 +186,9 @@ func (statefulSetStrategy) WarningsOnUpdate(ctx context.Context, obj, old runtim
 	for i, pvc := range newStatefulSet.Spec.VolumeClaimTemplates {
 		warnings = append(warnings, pvcutil.GetWarningsForPersistentVolumeClaimSpec(field.NewPath("spec", "volumeClaimTemplates").Index(i).Child("Spec"), pvc.Spec)...)
 	}
+	if newStatefulSet.Spec.RevisionHistoryLimit != nil && *newStatefulSet.Spec.RevisionHistoryLimit < 0 {
+		warnings = append(warnings, "spec.revisionHistoryLimit: a negative value retains all historical revisions; a value >= 0 is recommended")
+	}
 
 	return warnings
 }

pkg/registry/apps/statefulset/strategy_test.go

@@ -20,6 +20,7 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/util/intstr"
 	genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
@@ -28,6 +29,7 @@ import (
 	"k8s.io/kubernetes/pkg/apis/apps"
 	api "k8s.io/kubernetes/pkg/apis/core"
 	"k8s.io/kubernetes/pkg/features"
+	"k8s.io/utils/ptr"
 )
 
 func TestStatefulSetStrategy(t *testing.T) {
@@ -137,6 +139,38 @@ func TestStatefulSetStrategy(t *testing.T) {
 		}
 	})
 
+	t.Run("StatefulSet revisionHistoryLimit field validations on creation and updation", func(t *testing.T) {
+		// Test creation
+		oldSts := &apps.StatefulSet{
+			ObjectMeta: metav1.ObjectMeta{Name: "abc", Namespace: metav1.NamespaceDefault},
+			Spec: apps.StatefulSetSpec{
+				PodManagementPolicy:  apps.OrderedReadyPodManagement,
+				Selector:             &metav1.LabelSelector{MatchLabels: validSelector},
+				Template:             validPodTemplate.Template,
+				UpdateStrategy:       apps.StatefulSetUpdateStrategy{Type: apps.RollingUpdateStatefulSetStrategyType},
+				RevisionHistoryLimit: ptr.To(int32(-2)),
+			},
+		}
+
+		warnings := Strategy.WarningsOnCreate(ctx, oldSts)
+		if len(warnings) != 1 {
+			t.Errorf("expected one warning got %v", warnings)
+		}
+		if warnings[0] != "spec.revisionHistoryLimit: a negative value retains all historical revisions; a value >= 0 is recommended" {
+			t.Errorf("unexpected warning: %v", warnings)
+		}
+		oldSts.Spec.RevisionHistoryLimit = ptr.To(int32(2))
+		newSts := oldSts.DeepCopy()
+		newSts.Spec.RevisionHistoryLimit = ptr.To(int32(-2))
+		warnings = Strategy.WarningsOnUpdate(ctx, newSts, oldSts)
+		if len(warnings) != 1 {
+			t.Errorf("expected one warning got %v", warnings)
+		}
+		if warnings[0] != "spec.revisionHistoryLimit: a negative value retains all historical revisions; a value >= 0 is recommended" {
+			t.Errorf("unexpected warning: %v", warnings)
+		}
+	})
+
 	validPs = &apps.StatefulSet{
 		ObjectMeta: metav1.ObjectMeta{Name: ps.Name, Namespace: ps.Namespace, ResourceVersion: "1", Generation: 1},
 		Spec: apps.StatefulSetSpec{