dynamic resource allocation: avoid apiserver complaint about list con…

…tent

This fixes the following warning (error?) in the apiserver:

E0126 18:10:38.665239   16370 fieldmanager.go:210] "[SHOULD NOT HAPPEN] failed to update managedFields" err="failed to convert new object (test/claim-84; resource.k8s.io/v1alpha1, Kind=ResourceClaim) to smd typed: .status.reservedFor: element 0: associative list without keys has an element that's a map type" VersionKind="/, Kind=" namespace="test" name="claim-84"

The root cause is the same as in e50e8a0:
nothing in Kubernetes outright complains about a list of items where the item
type is comparable in Go, but not a simple type. This nonetheless isn't
supposed to be done in the API and can causes problems elsewhere.

For the ReservedFor field, everything seems to work okay except for the
warning. However, it's better to follow conventions and use a map. This is
possible in this case because UID is guaranteed to be a unique key.

Validation is now stricter than before, which is a good thing: previously,
two entries with the same UID were allowed as long as some other field was
different, which wasn't a situation that should have been allowed.

api/openapi-spec/v3/apis__resource.k8s.io__v1alpha1_openapi.json

@@ -466,7 +466,10 @@
               "default": {}
             },
             "type": "array",
-            "x-kubernetes-list-type": "set"
+            "x-kubernetes-list-map-keys": [
+              "uid"
+            ],
+            "x-kubernetes-list-type": "map"
           }
         },
         "type": "object"

pkg/apis/resource/validation/validation.go

@@ -18,6 +18,7 @@ package validation
 
 import (
 	apimachineryvalidation "k8s.io/apimachinery/pkg/api/validation"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	corevalidation "k8s.io/kubernetes/pkg/apis/core/validation"
@@ -131,8 +132,7 @@ func ValidateClaimStatusUpdate(resourceClaim, oldClaim *resource.ResourceClaim)
 	}
 
 	allErrs = append(allErrs, validateAllocationResult(resourceClaim.Status.Allocation, fldPath.Child("allocation"))...)
-	allErrs = append(allErrs, validateSliceIsASet(resourceClaim.Status.ReservedFor, resource.ResourceClaimReservedForMaxSize,
-		validateResourceClaimUserReference, fldPath.Child("reservedFor"))...)
+	allErrs = append(allErrs, validateResourceClaimConsumers(resourceClaim.Status.ReservedFor, resource.ResourceClaimReservedForMaxSize, fldPath.Child("reservedFor"))...)
 
 	// Now check for invariants that must be valid for a ResourceClaim.
 	if len(resourceClaim.Status.ReservedFor) > 0 {
@@ -231,6 +231,28 @@ func validateSliceIsASet[T comparable](slice []T, maxSize int, validateItem func
 	return allErrs
 }
 
+// validateResourceClaimConsumers ensures that the slice contains no duplicate UIDs and does not exceed a certain maximum size.
+func validateResourceClaimConsumers(consumers []resource.ResourceClaimConsumerReference, maxSize int, fldPath *field.Path) field.ErrorList {
+	var allErrs field.ErrorList
+	allUIDs := sets.New[types.UID]()
+	for i, consumer := range consumers {
+		idxPath := fldPath.Index(i)
+		if allUIDs.Has(consumer.UID) {
+			allErrs = append(allErrs, field.Duplicate(idxPath.Child("uid"), consumer.UID))
+		} else {
+			allErrs = append(allErrs, validateResourceClaimUserReference(consumer, idxPath)...)
+			allUIDs.Insert(consumer.UID)
+		}
+	}
+	if len(consumers) > maxSize {
+		// Dumping the entire field into the error message is likely to be too long,
+		// in particular when it is already beyond the maximum size. Instead this
+		// just shows the number of entries.
+		allErrs = append(allErrs, field.TooLongMaxLength(fldPath, len(consumers), maxSize))
+	}
+	return allErrs
+}
+
 // ValidatePodScheduling validates a PodScheduling.
 func ValidatePodScheduling(resourceClaim *resource.PodScheduling) field.ErrorList {
 	allErrs := corevalidation.ValidateObjectMeta(&resourceClaim.ObjectMeta, true, corevalidation.ValidatePodName, field.NewPath("metadata"))

pkg/apis/resource/validation/validation_resourceclaim_test.go

@@ -24,6 +24,7 @@ import (
 	"github.com/stretchr/testify/assert"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	"k8s.io/kubernetes/pkg/apis/core"
 	"k8s.io/kubernetes/pkg/apis/resource"
@@ -395,7 +396,7 @@ func TestValidateClaimStatusUpdate(t *testing.T) {
 						resource.ResourceClaimConsumerReference{
 							Resource: "pods",
 							Name:     fmt.Sprintf("foo-%d", i),
-							UID:      "1",
+							UID:      types.UID(fmt.Sprintf("%d", i)),
 						})
 				}
 				return claim
@@ -410,7 +411,7 @@ func TestValidateClaimStatusUpdate(t *testing.T) {
 						resource.ResourceClaimConsumerReference{
 							Resource: "pods",
 							Name:     fmt.Sprintf("foo-%d", i),
-							UID:      "1",
+							UID:      types.UID(fmt.Sprintf("%d", i)),
 						})
 				}
 				return claim
@@ -425,19 +426,15 @@ func TestValidateClaimStatusUpdate(t *testing.T) {
 						resource.ResourceClaimConsumerReference{
 							Resource: "pods",
 							Name:     fmt.Sprintf("foo-%d", i),
-							UID:      "1",
+							UID:      types.UID(fmt.Sprintf("%d", i)),
 						})
 				}
 				return claim
 			},
 		},
 		"invalid-reserved-for-duplicate": {
-			wantFailures: field.ErrorList{field.Duplicate(field.NewPath("status", "reservedFor").Index(1), resource.ResourceClaimConsumerReference{
-				Resource: "pods",
-				Name:     "foo",
-				UID:      "1",
-			})},
-			oldClaim: validAllocatedClaim,
+			wantFailures: field.ErrorList{field.Duplicate(field.NewPath("status", "reservedFor").Index(1).Child("uid"), types.UID("1"))},
+			oldClaim:     validAllocatedClaim,
 			update: func(claim *resource.ResourceClaim) *resource.ResourceClaim {
 				for i := 0; i < 2; i++ {
 					claim.Status.ReservedFor = append(claim.Status.ReservedFor,
@@ -463,7 +460,7 @@ func TestValidateClaimStatusUpdate(t *testing.T) {
 						resource.ResourceClaimConsumerReference{
 							Resource: "pods",
 							Name:     fmt.Sprintf("foo-%d", i),
-							UID:      "1",
+							UID:      types.UID(fmt.Sprintf("%d", i)),
 						})
 				}
 				return claim

staging/src/k8s.io/api/resource/v1alpha1/types.go

@@ -112,7 +112,8 @@ type ResourceClaimStatus struct {
 	// There can be at most 32 such reservations. This may get increased in
 	// the future, but not reduced.
 	//
-	// +listType=set
+	// +listType=map
+	// +listMapKey=uid
 	// +optional
 	ReservedFor []ResourceClaimConsumerReference `json:"reservedFor,omitempty" protobuf:"bytes,3,opt,name=reservedFor"`