Merge pull request kubernetes#78553 from caesarxuchao/alpha-gate-remainingItemCount

Protecting remainingItemCount behind a feature flag. Also updating the API doc

Author: k8s-ci-robot

api/openapi-spec/swagger.json

@@ -82,11 +82,18 @@ type ListMeta struct {
 	// message.
 	Continue string `json:"continue,omitempty" protobuf:"bytes,3,opt,name=continue"`
 
-	// RemainingItemCount is the number of subsequent items in the list which are not included in this
+	// remainingItemCount is the number of subsequent items in the list which are not included in this
 	// list response. If the list request contained label or field selectors, then the number of
-	// remaining items is unknown and this field will be unset. If the list is complete (either
-	// because it is unpaginated or because this is the last page), then there are no more remaining
-	// items and this field will also be unset.  Servers older than v1.15 do not set this field.
+	// remaining items is unknown and the field will be left unset and omitted during serialization.
+	// If the list is complete (either because it is not chunking or because this is the last chunk),
+	// then there are no more remaining items and this field will be left unset and omitted during
+	// serialization.
+	// Servers older than v1.15 do not set this field.
+	// The intended use of the remainingItemCount is *estimating* the size of a collection. Clients
+	// should not rely on the remainingItemCount to be set or to be exact.
+	//
+	// This field is alpha and can be changed or removed without notice.
+	//
 	// +optional
 	RemainingItemCount *int64 `json:"remainingItemCount,omitempty" protobuf:"bytes,4,opt,name=remainingItemCount"`
 }

staging/src/k8s.io/apiextensions-apiserver/pkg/generated/openapi/zz_generated.openapi.go

@@ -86,6 +86,13 @@ const (
 	// committing.
 	DryRun featuregate.Feature = "DryRun"
 
+	// owner: @caesarxuchao
+	// alpha: v1.15
+	//
+	// Allow apiservers to show a count of remaining items in the response
+	// to a chunking list request.
+	RemainingItemCount featuregate.Feature = "RemainingItemCount"
+
 	// owner: @apelisse, @lavalamp
 	// alpha: v1.14
 	//
@@ -141,6 +148,7 @@ var defaultKubernetesFeatureGates = map[featuregate.Feature]featuregate.FeatureS
 	APIResponseCompression:  {Default: false, PreRelease: featuregate.Alpha},
 	APIListChunking:         {Default: true, PreRelease: featuregate.Beta},
 	DryRun:                  {Default: true, PreRelease: featuregate.Beta},
+	RemainingItemCount:      {Default: false, PreRelease: featuregate.Alpha},
 	ServerSideApply:         {Default: false, PreRelease: featuregate.Alpha},
 	StorageVersionHash:      {Default: true, PreRelease: featuregate.Beta},
 	WinOverlay:              {Default: false, PreRelease: featuregate.Alpha},

staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/generated.proto

@@ -31,10 +31,13 @@ go_test(
         "//staging/src/k8s.io/apimachinery/pkg/watch:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/apis/example:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/apis/example/v1:go_default_library",
+        "//staging/src/k8s.io/apiserver/pkg/features:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage/etcd:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage/tests:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage/value:go_default_library",
+        "//staging/src/k8s.io/apiserver/pkg/util/feature:go_default_library",
+        "//staging/src/k8s.io/component-base/featuregate/testing:go_default_library",
         "//vendor/github.com/coreos/etcd/clientv3:go_default_library",
         "//vendor/github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes:go_default_library",
         "//vendor/github.com/coreos/etcd/integration:go_default_library",
@@ -66,10 +69,12 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/watch:go_default_library",
+        "//staging/src/k8s.io/apiserver/pkg/features:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage/etcd:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage/etcd/metrics:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage/value:go_default_library",
+        "//staging/src/k8s.io/apiserver/pkg/util/feature:go_default_library",
         "//vendor/github.com/coreos/etcd/clientv3:go_default_library",
         "//vendor/github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes:go_default_library",
         "//vendor/github.com/coreos/etcd/mvcc/mvccpb:go_default_library",

staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/types.go

@@ -36,10 +36,12 @@ import (
 	"k8s.io/apimachinery/pkg/conversion"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/watch"
+	"k8s.io/apiserver/pkg/features"
 	"k8s.io/apiserver/pkg/storage"
 	"k8s.io/apiserver/pkg/storage/etcd"
 	"k8s.io/apiserver/pkg/storage/etcd/metrics"
 	"k8s.io/apiserver/pkg/storage/value"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
 	utiltrace "k8s.io/utils/trace"
 )
 
@@ -622,9 +624,11 @@ func (s *store) List(ctx context.Context, key, resourceVersion string, pred stor
 		// getResp.Count counts in objects that do not match the pred.
 		// Instead of returning inaccurate count for non-empty selectors, we return nil.
 		// Only set remainingItemCount if the predicate is empty.
-		if pred.Empty() {
-			c := int64(getResp.Count - pred.Limit)
-			remainingItemCount = &c
+		if utilfeature.DefaultFeatureGate.Enabled(features.RemainingItemCount) {
+			if pred.Empty() {
+				c := int64(getResp.Count - pred.Limit)
+				remainingItemCount = &c
+			}
 		}
 		return s.versioner.UpdateList(listObj, uint64(returnedRV), next, remainingItemCount)
 	}

staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/types_swagger_doc_generated.go

@@ -44,10 +44,13 @@ import (
 	"k8s.io/apimachinery/pkg/watch"
 	"k8s.io/apiserver/pkg/apis/example"
 	examplev1 "k8s.io/apiserver/pkg/apis/example/v1"
+	"k8s.io/apiserver/pkg/features"
 	"k8s.io/apiserver/pkg/storage"
 	"k8s.io/apiserver/pkg/storage/etcd"
 	storagetests "k8s.io/apiserver/pkg/storage/tests"
 	"k8s.io/apiserver/pkg/storage/value"
+	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	featuregatetesting "k8s.io/component-base/featuregate/testing"
 	utilpointer "k8s.io/utils/pointer"
 )
 
@@ -752,6 +755,7 @@ func TestTransformationFailure(t *testing.T) {
 }
 
 func TestList(t *testing.T) {
+	defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.RemainingItemCount, true)()
 	codec := apitesting.TestCodec(codecs, examplev1.SchemeGroupVersion)
 	cluster := integration.NewClusterV3(t, &integration.ClusterConfig{Size: 1})
 	defer cluster.Terminate(t)

staging/src/k8s.io/apiserver/pkg/features/kube_features.go

@@ -65,8 +65,10 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/util/wait:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/watch:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/endpoints/discovery:go_default_library",
+        "//staging/src/k8s.io/apiserver/pkg/features:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage/names:go_default_library",
         "//staging/src/k8s.io/apiserver/pkg/storage/storagebackend:go_default_library",
+        "//staging/src/k8s.io/apiserver/pkg/util/feature:go_default_library",
         "//staging/src/k8s.io/client-go/discovery:go_default_library",
         "//staging/src/k8s.io/client-go/dynamic:go_default_library",
         "//staging/src/k8s.io/client-go/kubernetes:go_default_library",