Merge pull request #52949 from smarterclayton/enable_paging

Automatic merge from submit-queue (batch tested with PRs 52354, 52949, 53551). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Enable API chunking and promote to beta for 1.9

All list watchers default to using chunking.  The server by default fills pages to avoid low cardinality filters from making excessive numbers of requests.  Fix an issue with continuation tokens where a `../` could be used if the feature was enabled.

```release-note
API chunking via the `limit` and `continue` request parameters is promoted to beta in this release.  Client libraries using the Informer or ListWatch types will automatically opt in to chunking.
```

pkg/features/kube_features.go

@@ -201,7 +201,7 @@ var defaultKubernetesFeatureGates = map[utilfeature.Feature]utilfeature.FeatureS
 	genericfeatures.AdvancedAuditing:        {Default: true, PreRelease: utilfeature.Beta},
 	genericfeatures.APIResponseCompression:  {Default: false, PreRelease: utilfeature.Alpha},
 	genericfeatures.Initializers:            {Default: false, PreRelease: utilfeature.Alpha},
-	genericfeatures.APIListChunking:         {Default: false, PreRelease: utilfeature.Alpha},
+	genericfeatures.APIListChunking:         {Default: true, PreRelease: utilfeature.Beta},
 
 	// inherited features from apiextensions-apiserver, relisted here to get a conflict if it is changed
 	// unintentionally on either side:

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

@@ -58,6 +58,7 @@ const (
 
 	// owner: @smarterclayton
 	// alpha: v1.8
+	// beta: v1.9
 	//
 	// Allow API clients to retrieve resource lists in chunks rather than
 	// all at once.
@@ -76,5 +77,5 @@ var defaultKubernetesFeatureGates = map[utilfeature.Feature]utilfeature.FeatureS
 	AdvancedAuditing:        {Default: true, PreRelease: utilfeature.Beta},
 	APIResponseCompression:  {Default: false, PreRelease: utilfeature.Alpha},
 	Initializers:            {Default: false, PreRelease: utilfeature.Alpha},
-	APIListChunking:         {Default: false, PreRelease: utilfeature.Alpha},
+	APIListChunking:         {Default: true, PreRelease: utilfeature.Beta},
 }

staging/src/k8s.io/apiserver/pkg/storage/cacher.go

@@ -468,10 +468,15 @@ func (c *Cacher) GetToList(ctx context.Context, key string, resourceVersion stri
 // Implements storage.Interface.
 func (c *Cacher) List(ctx context.Context, key string, resourceVersion string, pred SelectionPredicate, listObj runtime.Object) error {
 	pagingEnabled := utilfeature.DefaultFeatureGate.Enabled(features.APIListChunking)
-	if resourceVersion == "" || (pagingEnabled && (len(pred.Continue) > 0 || pred.Limit > 0)) {
+	hasContinuation := pagingEnabled && len(pred.Continue) > 0
+	hasLimit := pagingEnabled && pred.Limit > 0 && resourceVersion != "0"
+	if resourceVersion == "" || hasContinuation || hasLimit {
 		// If resourceVersion is not specified, serve it from underlying
-		// storage (for backward compatibility). If a continuation or limit is
+		// storage (for backward compatibility). If a continuation is
 		// requested, serve it from the underlying storage as well.
+		// Limits are only sent to storage when resourceVersion is non-zero
+		// since the watch cache isn't able to perform continuations, and
+		// limits are ignored when resource version is zero.
 		return c.storage.List(ctx, key, resourceVersion, pred, listObj)
 	}
 

staging/src/k8s.io/apiserver/pkg/storage/etcd3/BUILD

@@ -18,6 +18,7 @@ go_test(
         "//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",
+        "//vendor/github.com/coreos/pkg/capnslog:go_default_library",
         "//vendor/golang.org/x/net/context:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/api/errors:go_default_library",
         "//vendor/k8s.io/apimachinery/pkg/api/testing:go_default_library",

staging/src/k8s.io/apiserver/pkg/storage/etcd3/store.go

@@ -396,11 +396,11 @@ func (s *store) GetToList(ctx context.Context, key string, resourceVersion strin
 	if err != nil {
 		return storage.NewInternalError(err.Error())
 	}
-	elems := []*elemForDecode{{
+	v, err := conversion.EnforcePtr(listPtr)
-		data: data,
+	if err != nil || v.Kind() != reflect.Slice {
-		rev:  uint64(getResp.Kvs[0].ModRevision),
+		panic("need ptr to slice")
-	}}
+	}
-	if err := decodeList(elems, storage.SimpleFilter(pred), listPtr, s.codec, s.versioner); err != nil {
+	if err := appendListItem(v, data, uint64(getResp.Kvs[0].ModRevision), storage.SimpleFilter(pred), s.codec, s.versioner); err != nil {
 		return err
 	}
 	// update version with cluster level revision
@@ -429,25 +429,26 @@ func decodeContinue(continueValue, keyPrefix string) (fromKey string, rv int64,
 		return "", 0, fmt.Errorf("continue key is not valid: %v", err)
 	}
 	switch c.APIVersion {
-	case "v1alpha1":
+	case "meta.k8s.io/v1":
 		if c.ResourceVersion == 0 {
-			return "", 0, fmt.Errorf("continue key is not valid: incorrect encoded start resourceVersion (version v1alpha1)")
+			return "", 0, fmt.Errorf("continue key is not valid: incorrect encoded start resourceVersion (version meta.k8s.io/v1)")
 		}
 		if len(c.StartKey) == 0 {
-			return "", 0, fmt.Errorf("continue key is not valid: encoded start key empty (version v1alpha1)")
+			return "", 0, fmt.Errorf("continue key is not valid: encoded start key empty (version meta.k8s.io/v1)")
 		}
 		// defend against path traversal attacks by clients - path.Clean will ensure that startKey cannot
 		// be at a higher level of the hierarchy, and so when we append the key prefix we will end up with
 		// continue start key that is fully qualified and cannot range over anything less specific than
 		// keyPrefix.
-		cleaned := path.Clean(c.StartKey)
+		key := c.StartKey
-		if cleaned != c.StartKey || cleaned == "." || cleaned == "/" {
+		if !strings.HasPrefix(key, "/") {
-			return "", 0, fmt.Errorf("continue key is not valid: %s", cleaned)
+			key = "/" + key
 		}
-		if len(cleaned) == 0 {
+		cleaned := path.Clean(key)
-			return "", 0, fmt.Errorf("continue key is not valid: encoded start key empty (version 0)")
+		if cleaned != key {
+			return "", 0, fmt.Errorf("continue key is not valid: %s", c.StartKey)
 		}
-		return keyPrefix + cleaned, c.ResourceVersion, nil
+		return keyPrefix + cleaned[1:], c.ResourceVersion, nil
 	default:
 		return "", 0, fmt.Errorf("continue key is not valid: server does not recognize this encoded version %q", c.APIVersion)
 	}
@@ -459,7 +460,7 @@ func encodeContinue(key, keyPrefix string, resourceVersion int64) (string, error
 	if nextKey == key {
 		return "", fmt.Errorf("unable to encode next field: the key and key prefix do not match")
 	}
-	out, err := json.Marshal(&continueToken{APIVersion: "v1alpha1", ResourceVersion: resourceVersion, StartKey: nextKey})
+	out, err := json.Marshal(&continueToken{APIVersion: "meta.k8s.io/v1", ResourceVersion: resourceVersion, StartKey: nextKey})
 	if err != nil {
 		return "", err
 	}
@@ -472,7 +473,14 @@ func (s *store) List(ctx context.Context, key, resourceVersion string, pred stor
 	if err != nil {
 		return err
 	}
+	v, err := conversion.EnforcePtr(listPtr)
+	if err != nil || v.Kind() != reflect.Slice {
+		panic("need ptr to slice")
+	}
+
+	if s.pathPrefix != "" {
 		key = path.Join(s.pathPrefix, key)
+	}
 	// We need to make sure the key ended with "/" so that we only get children "directories".
 	// e.g. if we have key "/a", "/a/b", "/ab", getting keys with prefix "/a" will return all three,
 	// while with prefix "/a/" will return only "/a/b" which is the correct answer.
@@ -481,81 +489,166 @@ func (s *store) List(ctx context.Context, key, resourceVersion string, pred stor
 	}
 	keyPrefix := key
 
+	filter := storage.SimpleFilter(pred)
+
 	// set the appropriate clientv3 options to filter the returned data set
+	var paging bool
 	options := make([]clientv3.OpOption, 0, 4)
 	if s.pagingEnabled && pred.Limit > 0 {
+		paging = true
 		options = append(options, clientv3.WithLimit(pred.Limit))
 	}
+
 	var returnedRV int64
 	switch {
 	case s.pagingEnabled && len(pred.Continue) > 0:
 		continueKey, continueRV, err := decodeContinue(pred.Continue, keyPrefix)
 		if err != nil {
-			return err
+			return apierrors.NewBadRequest(fmt.Sprintf("invalid continue token: %v", err))
 		}
 
-		options = append(options, clientv3.WithRange(clientv3.GetPrefixRangeEnd(key)))
+		if len(resourceVersion) > 0 && resourceVersion != "0" {
+			return apierrors.NewBadRequest("specifying resource version is not allowed when using continue")
+		}
+
+		rangeEnd := clientv3.GetPrefixRangeEnd(keyPrefix)
+		options = append(options, clientv3.WithRange(rangeEnd))
 		key = continueKey
 
 		options = append(options, clientv3.WithRev(continueRV))
 		returnedRV = continueRV
 
-	case len(resourceVersion) > 0:
+	case s.pagingEnabled && pred.Limit > 0:
+		if len(resourceVersion) > 0 {
 			fromRV, err := strconv.ParseInt(resourceVersion, 10, 64)
 			if err != nil {
-			return fmt.Errorf("invalid resource version: %v", err)
+				return apierrors.NewBadRequest(fmt.Sprintf("invalid resource version: %v", err))
+			}
+			if fromRV > 0 {
+				options = append(options, clientv3.WithRev(fromRV))
+			}
+			returnedRV = fromRV
 		}
 
-		options = append(options, clientv3.WithPrefix(), clientv3.WithRev(fromRV))
+		rangeEnd := clientv3.GetPrefixRangeEnd(keyPrefix)
-		returnedRV = fromRV
+		options = append(options, clientv3.WithRange(rangeEnd))
 
 	default:
+		if len(resourceVersion) > 0 {
+			fromRV, err := strconv.ParseInt(resourceVersion, 10, 64)
+			if err != nil {
+				return apierrors.NewBadRequest(fmt.Sprintf("invalid resource version: %v", err))
+			}
+			if fromRV > 0 {
+				options = append(options, clientv3.WithRev(fromRV))
+			}
+			returnedRV = fromRV
+		}
+
 		options = append(options, clientv3.WithPrefix())
 	}
 
+	// loop until we have filled the requested limit from etcd or there are no more results
+	var lastKey []byte
+	var hasMore bool
+	for {
 		getResp, err := s.client.KV.Get(ctx, key, options...)
 		if err != nil {
 			return interpretListError(err, len(pred.Continue) > 0)
 		}
+		hasMore = getResp.More
 
-	elems := make([]*elemForDecode, 0, len(getResp.Kvs))
+		if len(getResp.Kvs) == 0 && getResp.More {
+			return fmt.Errorf("no results were found, but etcd indicated there were more values remaining")
+		}
+
+		// avoid small allocations for the result slice, since this can be called in many
+		// different contexts and we don't know how significantly the result will be filtered
+		if pred.Empty() {
+			growSlice(v, len(getResp.Kvs))
+		} else {
+			growSlice(v, 2048, len(getResp.Kvs))
+		}
+
+		// take items from the response until the bucket is full, filtering as we go
 		for _, kv := range getResp.Kvs {
+			if paging && int64(v.Len()) >= pred.Limit {
+				hasMore = true
+				break
+			}
+			lastKey = kv.Key
+
 			data, _, err := s.transformer.TransformFromStorage(kv.Value, authenticatedDataString(kv.Key))
 			if err != nil {
 				utilruntime.HandleError(fmt.Errorf("unable to transform key %q: %v", kv.Key, err))
 				continue
 			}
 
-		elems = append(elems, &elemForDecode{
+			if err := appendListItem(v, data, uint64(kv.ModRevision), filter, s.codec, s.versioner); err != nil {
-			data: data,
-			rev:  uint64(kv.ModRevision),
-		})
-	}
-
-	if err := decodeList(elems, storage.SimpleFilter(pred), listPtr, s.codec, s.versioner); err != nil {
 				return err
 			}
+		}
 
 		// indicate to the client which resource version was returned
 		if returnedRV == 0 {
 			returnedRV = getResp.Header.Revision
 		}
-	switch {
+
-	case !getResp.More:
+		// no more results remain or we didn't request paging
-		// no continuation
+		if !hasMore || !paging {
-		return s.versioner.UpdateList(listObj, uint64(returnedRV), "")
+			break
-	case len(getResp.Kvs) == 0:
+		}
-		return fmt.Errorf("no results were found, but etcd indicated there were more values")
+		// we're paging but we have filled our bucket
-	default:
+		if int64(v.Len()) >= pred.Limit {
+			break
+		}
+		key = string(lastKey) + "\x00"
+	}
+
+	// instruct the client to begin querying from immediately after the last key we returned
+	// we never return a key that the client wouldn't be allowed to see
+	if hasMore {
 		// we want to start immediately after the last key
-		// TODO: this reveals info about certain keys
+		next, err := encodeContinue(string(lastKey)+"\x00", keyPrefix, returnedRV)
-		key := string(getResp.Kvs[len(getResp.Kvs)-1].Key)
-		next, err := encodeContinue(key+"\x00", keyPrefix, returnedRV)
 		if err != nil {
 			return err
 		}
 		return s.versioner.UpdateList(listObj, uint64(returnedRV), next)
 	}
+
+	// no continuation
+	return s.versioner.UpdateList(listObj, uint64(returnedRV), "")
+}
+
+// growSlice takes a slice value and grows its capacity up
+// to the maximum of the passed sizes or maxCapacity, whichever
+// is smaller. Above maxCapacity decisions about allocation are left
+// to the Go runtime on append. This allows a caller to make an
+// educated guess about the potential size of the total list while
+// still avoiding overly aggressive initial allocation. If sizes
+// is empty maxCapacity will be used as the size to grow.
+func growSlice(v reflect.Value, maxCapacity int, sizes ...int) {
+	cap := v.Cap()
+	max := cap
+	for _, size := range sizes {
+		if size > max {
+			max = size
+		}
+	}
+	if len(sizes) == 0 || max > maxCapacity {
+		max = maxCapacity
+	}
+	if max <= cap {
+		return
+	}
+	if v.Len() > 0 {
+		extra := reflect.MakeSlice(v.Type(), 0, max)
+		reflect.Copy(extra, v)
+		v.Set(extra)
+	} else {
+		extra := reflect.MakeSlice(v.Type(), 0, max)
+		v.Set(extra)
+	}
 }
 
 // Watch implements storage.Interface.Watch.
@@ -677,24 +770,17 @@ func decode(codec runtime.Codec, versioner storage.Versioner, value []byte, objP
 	return nil
 }
 
-// decodeList decodes a list of values into a list of objects, with resource version set to corresponding rev.
+// appendListItem decodes and appends the object (if it passes filter) to v, which must be a slice.
-// On success, ListPtr would be set to the list of objects.
+func appendListItem(v reflect.Value, data []byte, rev uint64, filter storage.FilterFunc, codec runtime.Codec, versioner storage.Versioner) error {
-func decodeList(elems []*elemForDecode, filter storage.FilterFunc, listPtr interface{}, codec runtime.Codec, versioner storage.Versioner) error {
+	obj, _, err := codec.Decode(data, nil, reflect.New(v.Type().Elem()).Interface().(runtime.Object))
-	v, err := conversion.EnforcePtr(listPtr)
-	if err != nil || v.Kind() != reflect.Slice {
-		panic("need ptr to slice")
-	}
-	for _, elem := range elems {
-		obj, _, err := codec.Decode(elem.data, nil, reflect.New(v.Type().Elem()).Interface().(runtime.Object))
 	if err != nil {
 		return err
 	}
 	// being unable to set the version does not prevent the object from being extracted
-		versioner.UpdateObject(obj, elem.rev)
+	versioner.UpdateObject(obj, rev)
 	if filter(obj) {
 		v.Set(reflect.Append(v, reflect.ValueOf(obj).Elem()))
 	}
-	}
 	return nil
 }
 

staging/src/k8s.io/apiserver/pkg/storage/etcd3/store_test.go

@@ -29,6 +29,7 @@ import (
 
 	"github.com/coreos/etcd/clientv3"
 	"github.com/coreos/etcd/integration"
+	"github.com/coreos/pkg/capnslog"
 	"golang.org/x/net/context"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	apitesting "k8s.io/apimachinery/pkg/api/testing"
@@ -55,6 +56,8 @@ func init() {
 	metav1.AddToGroupVersion(scheme, metav1.SchemeGroupVersion)
 	example.AddToScheme(scheme)
 	examplev1.AddToScheme(scheme)
+
+	capnslog.SetGlobalLogLevel(capnslog.CRITICAL)
 }
 
 // prefixTransformer adds and verifies that all data has the correct prefix on its way in and out.
@@ -727,25 +730,44 @@ func TestList(t *testing.T) {
 	//  |            - test
 	//  |
 	//   - two-level/
-	//               - 1/
+	//  |            - 1/
+	//  |           |   - test
+	//  |           |
+	//  |            - 2/
 	//  |               - test
 	//  |
-	//               - 2/
+	//   - z-level/
-	//                  - test
+	//               - 3/
+	//              |   - test
+	//              |
+	//               - 3/
+	//                  - test-2
 	preset := []struct {
 		key       string
 		obj       *example.Pod
 		storedObj *example.Pod
-	}{{
+	}{
+		{
 			key: "/one-level/test",
 			obj: &example.Pod{ObjectMeta: metav1.ObjectMeta{Name: "foo"}},
-	}, {
+		},
+		{
 			key: "/two-level/1/test",
 			obj: &example.Pod{ObjectMeta: metav1.ObjectMeta{Name: "foo"}},
-	}, {
+		},
+		{
 			key: "/two-level/2/test",
 			obj: &example.Pod{ObjectMeta: metav1.ObjectMeta{Name: "bar"}},
-	}}
+		},
+		{
+			key: "/z-level/3/test",
+			obj: &example.Pod{ObjectMeta: metav1.ObjectMeta{Name: "fourth"}},
+		},
+		{
+			key: "/z-level/3/test-2",
+			obj: &example.Pod{ObjectMeta: metav1.ObjectMeta{Name: "bar"}},
+		},
+	}
 
 	for i, ps := range preset {
 		preset[i].storedObj = &example.Pod{}
@@ -763,110 +785,302 @@ func TestList(t *testing.T) {
 		t.Fatal(err)
 	}
 
+	getAttrs := func(obj runtime.Object) (labels.Set, fields.Set, bool, error) {
+		pod := obj.(*example.Pod)
+		return nil, fields.Set{"metadata.name": pod.Name}, pod.Initializers != nil, nil
+	}
+
 	tests := []struct {
+		name           string
 		disablePaging  bool
+		rv             string
 		prefix         string
 		pred           storage.SelectionPredicate
 		expectedOut    []*example.Pod
 		expectContinue bool
+		expectError    bool
 	}{
-		{ // test List on existing key
+		{
+			name:        "rejects invalid resource version",
+			prefix:      "/",
+			pred:        storage.Everything,
+			rv:          "abc",
+			expectError: true,
+		},
+		{
+			name:   "rejects resource version and continue token",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Label:    labels.Everything(),
+				Field:    fields.Everything(),
+				Limit:    1,
+				Continue: secondContinuation,
+			},
+			rv:          "1",
+			expectError: true,
+		},
+		{
+			name:        "test List on existing key",
 			prefix:      "/one-level/",
 			pred:        storage.Everything,
 			expectedOut: []*example.Pod{preset[0].storedObj},
 		},
-		{ // test List on non-existing key
+		{
+			name:        "test List on non-existing key",
 			prefix:      "/non-existing/",
 			pred:        storage.Everything,
 			expectedOut: nil,
 		},
-		{ // test List with pod name matching
+		{
+			name:   "test List with pod name matching",
 			prefix: "/one-level/",
 			pred: storage.SelectionPredicate{
 				Label: labels.Everything(),
-				Field: fields.ParseSelectorOrDie("metadata.name!=" + preset[0].storedObj.Name),
+				Field: fields.ParseSelectorOrDie("metadata.name!=foo"),
-				GetAttrs: func(obj runtime.Object) (labels.Set, fields.Set, bool, error) {
-					pod := obj.(*example.Pod)
-					return nil, fields.Set{"metadata.name": pod.Name}, pod.Initializers != nil, nil
-				},
 			},
 			expectedOut: nil,
 		},
-		{ // test List with limit
+		{
+			name:   "test List with limit",
 			prefix: "/two-level/",
 			pred: storage.SelectionPredicate{
 				Label: labels.Everything(),
 				Field: fields.Everything(),
 				Limit: 1,
-				GetAttrs: func(obj runtime.Object) (labels.Set, fields.Set, bool, error) {
-					pod := obj.(*example.Pod)
-					return nil, fields.Set{"metadata.name": pod.Name}, pod.Initializers != nil, nil
-				},
 			},
 			expectedOut:    []*example.Pod{preset[1].storedObj},
 			expectContinue: true,
 		},
-		{ // test List with limit when paging disabled
+		{
+			name:          "test List with limit when paging disabled",
 			disablePaging: true,
 			prefix:        "/two-level/",
 			pred: storage.SelectionPredicate{
 				Label: labels.Everything(),
 				Field: fields.Everything(),
 				Limit: 1,
-				GetAttrs: func(obj runtime.Object) (labels.Set, fields.Set, bool, error) {
-					pod := obj.(*example.Pod)
-					return nil, fields.Set{"metadata.name": pod.Name}, pod.Initializers != nil, nil
-				},
 			},
 			expectedOut:    []*example.Pod{preset[1].storedObj, preset[2].storedObj},
 			expectContinue: false,
 		},
-		{ // test List with pregenerated continue token
+		{
+			name:   "test List with pregenerated continue token",
 			prefix: "/two-level/",
 			pred: storage.SelectionPredicate{
 				Label:    labels.Everything(),
 				Field:    fields.Everything(),
 				Limit:    1,
 				Continue: secondContinuation,
-				GetAttrs: func(obj runtime.Object) (labels.Set, fields.Set, bool, error) {
-					pod := obj.(*example.Pod)
-					return nil, fields.Set{"metadata.name": pod.Name}, pod.Initializers != nil, nil
-				},
 			},
 			expectedOut: []*example.Pod{preset[2].storedObj},
 		},
-		{ // test List with multiple levels of directories and expect flattened result
+		{
+			name:   "ignores resource version 0 for List with pregenerated continue token",
+			prefix: "/two-level/",
+			pred: storage.SelectionPredicate{
+				Label:    labels.Everything(),
+				Field:    fields.Everything(),
+				Limit:    1,
+				Continue: secondContinuation,
+			},
+			rv:          "0",
+			expectedOut: []*example.Pod{preset[2].storedObj},
+		},
+		{
+			name:        "test List with multiple levels of directories and expect flattened result",
 			prefix:      "/two-level/",
 			pred:        storage.Everything,
 			expectedOut: []*example.Pod{preset[1].storedObj, preset[2].storedObj},
 		},
+		{
+			name:   "test List with filter returning only one item, ensure only a single page returned",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Field: fields.OneTermEqualSelector("metadata.name", "fourth"),
+				Label: labels.Everything(),
+				Limit: 1,
+			},
+			expectedOut:    []*example.Pod{preset[3].storedObj},
+			expectContinue: true,
+		},
+		{
+			name:   "test List with filter returning only one item, covers the entire list",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Field: fields.OneTermEqualSelector("metadata.name", "fourth"),
+				Label: labels.Everything(),
+				Limit: 2,
+			},
+			expectedOut:    []*example.Pod{preset[3].storedObj},
+			expectContinue: false,
+		},
+		{
+			name:   "test List with filter returning only one item, covers the entire list, with resource version 0",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Field: fields.OneTermEqualSelector("metadata.name", "fourth"),
+				Label: labels.Everything(),
+				Limit: 2,
+			},
+			rv:             "0",
+			expectedOut:    []*example.Pod{preset[3].storedObj},
+			expectContinue: false,
+		},
+		{
+			name:   "test List with filter returning two items, more pages possible",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Field: fields.OneTermEqualSelector("metadata.name", "foo"),
+				Label: labels.Everything(),
+				Limit: 2,
+			},
+			expectContinue: true,
+			expectedOut:    []*example.Pod{preset[0].storedObj, preset[1].storedObj},
+		},
+		{
+			name:   "filter returns two items split across multiple pages",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Field: fields.OneTermEqualSelector("metadata.name", "bar"),
+				Label: labels.Everything(),
+				Limit: 2,
+			},
+			expectedOut: []*example.Pod{preset[2].storedObj, preset[4].storedObj},
+		},
+		{
+			name:   "filter returns one item for last page, ends on last item, not full",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Field:    fields.OneTermEqualSelector("metadata.name", "bar"),
+				Label:    labels.Everything(),
+				Limit:    2,
+				Continue: encodeContinueOrDie("meta.k8s.io/v1", int64(continueRV), "z-level/3"),
+			},
+			expectedOut: []*example.Pod{preset[4].storedObj},
+		},
+		{
+			name:   "filter returns one item for last page, starts on last item, full",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Field:    fields.OneTermEqualSelector("metadata.name", "bar"),
+				Label:    labels.Everything(),
+				Limit:    1,
+				Continue: encodeContinueOrDie("meta.k8s.io/v1", int64(continueRV), "z-level/3/test-2"),
+			},
+			expectedOut: []*example.Pod{preset[4].storedObj},
+		},
+		{
+			name:   "filter returns one item for last page, starts on last item, partial page",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Field:    fields.OneTermEqualSelector("metadata.name", "bar"),
+				Label:    labels.Everything(),
+				Limit:    2,
+				Continue: encodeContinueOrDie("meta.k8s.io/v1", int64(continueRV), "z-level/3/test-2"),
+			},
+			expectedOut: []*example.Pod{preset[4].storedObj},
+		},
+		{
+			name:   "filter returns two items, page size equal to total list size",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Field: fields.OneTermEqualSelector("metadata.name", "bar"),
+				Label: labels.Everything(),
+				Limit: 5,
+			},
+			expectedOut: []*example.Pod{preset[2].storedObj, preset[4].storedObj},
+		},
+		{
+			name:   "filter returns one item, page size equal to total list size",
+			prefix: "/",
+			pred: storage.SelectionPredicate{
+				Field: fields.OneTermEqualSelector("metadata.name", "fourth"),
+				Label: labels.Everything(),
+				Limit: 5,
+			},
+			expectedOut: []*example.Pod{preset[3].storedObj},
+		},
+	}
+
+	for _, tt := range tests {
+		if tt.pred.GetAttrs == nil {
+			tt.pred.GetAttrs = getAttrs
 		}
 
-	for i, tt := range tests {
 		out := &example.PodList{}
 		var err error
 		if tt.disablePaging {
-			err = disablePagingStore.List(ctx, tt.prefix, "0", tt.pred, out)
+			err = disablePagingStore.List(ctx, tt.prefix, tt.rv, tt.pred, out)
 		} else {
-			err = store.List(ctx, tt.prefix, "0", tt.pred, out)
+			err = store.List(ctx, tt.prefix, tt.rv, tt.pred, out)
+		}
+		if (err != nil) != tt.expectError {
+			t.Errorf("(%s): List failed: %v", tt.name, err)
 		}
 		if err != nil {
-			t.Fatalf("#%d: List failed: %v", i, err)
+			continue
 		}
 		if (len(out.Continue) > 0) != tt.expectContinue {
-			t.Errorf("#%d: unexpected continue token: %v", i, out.Continue)
+			t.Errorf("(%s): unexpected continue token: %q", tt.name, out.Continue)
 		}
 		if len(tt.expectedOut) != len(out.Items) {
-			t.Errorf("#%d: length of list want=%d, get=%d", i, len(tt.expectedOut), len(out.Items))
+			t.Errorf("(%s): length of list want=%d, got=%d", tt.name, len(tt.expectedOut), len(out.Items))
 			continue
 		}
 		for j, wantPod := range tt.expectedOut {
 			getPod := &out.Items[j]
 			if !reflect.DeepEqual(wantPod, getPod) {
-				t.Errorf("#%d: pod want=%#v, get=%#v", i, wantPod, getPod)
+				t.Errorf("(%s): pod want=%#v, got=%#v", tt.name, wantPod, getPod)
 			}
 		}
 	}
+}
+
+func TestListContinuation(t *testing.T) {
+	codec := apitesting.TestCodec(codecs, examplev1.SchemeGroupVersion)
+	cluster := integration.NewClusterV3(t, &integration.ClusterConfig{Size: 1})
+	defer cluster.Terminate(t)
+	store := newStore(cluster.RandClient(), false, true, codec, "", prefixTransformer{prefix: []byte(defaultTestPrefix)})
+	ctx := context.Background()
+
+	// Setup storage with the following structure:
+	//  /
+	//   - one-level/
+	//  |            - test
+	//  |
+	//   - two-level/
+	//               - 1/
+	//              |   - test
+	//              |
+	//               - 2/
+	//                  - test
+	//
+	preset := []struct {
+		key       string
+		obj       *example.Pod
+		storedObj *example.Pod
+	}{
+		{
+			key: "/one-level/test",
+			obj: &example.Pod{ObjectMeta: metav1.ObjectMeta{Name: "foo"}},
+		},
+		{
+			key: "/two-level/1/test",
+			obj: &example.Pod{ObjectMeta: metav1.ObjectMeta{Name: "foo"}},
+		},
+		{
+			key: "/two-level/2/test",
+			obj: &example.Pod{ObjectMeta: metav1.ObjectMeta{Name: "bar"}},
+		},
+	}
+
+	for i, ps := range preset {
+		preset[i].storedObj = &example.Pod{}
+		err := store.Create(ctx, ps.key, ps.obj, preset[i].storedObj, 0)
+		if err != nil {
+			t.Fatalf("Set failed: %v", err)
+		}
+	}
 
 	// test continuations
 	out := &example.PodList{}
@@ -994,16 +1208,16 @@ func Test_decodeContinue(t *testing.T) {
 		wantRv      int64
 		wantErr     bool
 	}{
-		{name: "valid", args: args{continueValue: encodeContinueOrDie("v1alpha1", 1, "key"), keyPrefix: "/test/"}, wantRv: 1, wantFromKey: "/test/key"},
+		{name: "valid", args: args{continueValue: encodeContinueOrDie("meta.k8s.io/v1", 1, "key"), keyPrefix: "/test/"}, wantRv: 1, wantFromKey: "/test/key"},
+		{name: "root path", args: args{continueValue: encodeContinueOrDie("meta.k8s.io/v1", 1, "/"), keyPrefix: "/test/"}, wantRv: 1, wantFromKey: "/test/"},
 
 		{name: "empty version", args: args{continueValue: encodeContinueOrDie("", 1, "key"), keyPrefix: "/test/"}, wantErr: true},
 		{name: "invalid version", args: args{continueValue: encodeContinueOrDie("v1", 1, "key"), keyPrefix: "/test/"}, wantErr: true},
 
-		{name: "path traversal - parent", args: args{continueValue: encodeContinueOrDie("v1alpha", 1, "../key"), keyPrefix: "/test/"}, wantErr: true},
+		{name: "path traversal - parent", args: args{continueValue: encodeContinueOrDie("meta.k8s.io/v1", 1, "../key"), keyPrefix: "/test/"}, wantErr: true},
-		{name: "path traversal - local", args: args{continueValue: encodeContinueOrDie("v1alpha", 1, "./key"), keyPrefix: "/test/"}, wantErr: true},
+		{name: "path traversal - local", args: args{continueValue: encodeContinueOrDie("meta.k8s.io/v1", 1, "./key"), keyPrefix: "/test/"}, wantErr: true},
-		{name: "path traversal - double parent", args: args{continueValue: encodeContinueOrDie("v1alpha", 1, "./../key"), keyPrefix: "/test/"}, wantErr: true},
+		{name: "path traversal - double parent", args: args{continueValue: encodeContinueOrDie("meta.k8s.io/v1", 1, "./../key"), keyPrefix: "/test/"}, wantErr: true},
-		{name: "path traversal - after parent", args: args{continueValue: encodeContinueOrDie("v1alpha", 1, "key/../.."), keyPrefix: "/test/"}, wantErr: true},
+		{name: "path traversal - after parent", args: args{continueValue: encodeContinueOrDie("meta.k8s.io/v1", 1, "key/../.."), keyPrefix: "/test/"}, wantErr: true},
-		{name: "path traversal - separator", args: args{continueValue: encodeContinueOrDie("v1alpha", 1, "/"), keyPrefix: "/test/"}, wantErr: true},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -1021,3 +1235,68 @@ func Test_decodeContinue(t *testing.T) {
 		})
 	}
 }
+
+func Test_growSlice(t *testing.T) {
+	type args struct {
+		t               reflect.Type
+		initialCapacity int
+		v               reflect.Value
+		maxCapacity     int
+		sizes           []int
+	}
+	tests := []struct {
+		name string
+		args args
+		cap  int
+	}{
+		{
+			name: "empty",
+			args: args{v: reflect.ValueOf([]example.Pod{})},
+			cap:  0,
+		},
+		{
+			name: "no sizes",
+			args: args{v: reflect.ValueOf([]example.Pod{}), maxCapacity: 10},
+			cap:  10,
+		},
+		{
+			name: "above maxCapacity",
+			args: args{v: reflect.ValueOf([]example.Pod{}), maxCapacity: 10, sizes: []int{1, 12}},
+			cap:  10,
+		},
+		{
+			name: "takes max",
+			args: args{v: reflect.ValueOf([]example.Pod{}), maxCapacity: 10, sizes: []int{8, 4}},
+			cap:  8,
+		},
+		{
+			name: "with existing capacity above max",
+			args: args{initialCapacity: 12, maxCapacity: 10, sizes: []int{8, 4}},
+			cap:  12,
+		},
+		{
+			name: "with existing capacity below max",
+			args: args{initialCapacity: 5, maxCapacity: 10, sizes: []int{8, 4}},
+			cap:  8,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if tt.args.initialCapacity > 0 {
+				tt.args.v = reflect.ValueOf(make([]example.Pod, 0, tt.args.initialCapacity))
+			}
+			// reflection requires that the value be addressible in order to call set,
+			// so we must ensure the value we created is available on the heap (not a problem
+			// for normal usage)
+			if !tt.args.v.CanAddr() {
+				x := reflect.New(tt.args.v.Type())
+				x.Elem().Set(tt.args.v)
+				tt.args.v = x.Elem()
+			}
+			growSlice(tt.args.v, tt.args.maxCapacity, tt.args.sizes...)
+			if tt.cap != tt.args.v.Cap() {
+				t.Errorf("Unexpected capacity: got=%d want=%d", tt.args.v.Cap(), tt.cap)
+			}
+		})
+	}
+}

staging/src/k8s.io/client-go/tools/cache/listwatch.go

@@ -51,8 +51,7 @@ type WatchFunc func(options metav1.ListOptions) (watch.Interface, error)
 type ListWatch struct {
 	ListFunc  ListFunc
 	WatchFunc WatchFunc
-	// DisableChunking requests no chunking for this list watcher. It has no effect in Kubernetes 1.8, but in
+	// DisableChunking requests no chunking for this list watcher.
-	// 1.9 will allow a controller to opt out of chunking.
 	DisableChunking bool
 }
 
@@ -93,9 +92,7 @@ func timeoutFromListOptions(options metav1.ListOptions) time.Duration {
 
 // List a set of apiserver resources
 func (lw *ListWatch) List(options metav1.ListOptions) (runtime.Object, error) {
-	// chunking will become the default for list watchers starting in Kubernetes 1.9, unless
+	if !lw.DisableChunking {
-	// otherwise disabled.
-	if false && !lw.DisableChunking {
 		return pager.New(pager.SimplePageFunc(lw.ListFunc)).List(context.TODO(), options)
 	}
 	return lw.ListFunc(options)

test/e2e/apimachinery/BUILD

@@ -9,6 +9,7 @@ go_library(
     name = "go_default_library",
     srcs = [
         "aggregator.go",
+        "chunking.go",
         "custom_resource_definition.go",
         "etcd_failure.go",
         "framework.go",
@@ -58,6 +59,7 @@ go_library(
         "//vendor/k8s.io/client-go/kubernetes:go_default_library",
         "//vendor/k8s.io/client-go/util/cert:go_default_library",
         "//vendor/k8s.io/client-go/util/retry:go_default_library",
+        "//vendor/k8s.io/client-go/util/workqueue:go_default_library",
         "//vendor/k8s.io/kube-aggregator/pkg/apis/apiregistration/v1beta1:go_default_library",
         "//vendor/k8s.io/sample-apiserver/pkg/apis/wardle/v1alpha1:go_default_library",
     ],

test/e2e/apimachinery/chunking.go

@@ -0,0 +1,99 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package apimachinery
+
+import (
+	"fmt"
+	"math/rand"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+
+	"k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/util/workqueue"
+	"k8s.io/kubernetes/test/e2e/framework"
+)
+
+const numberOfTotalResources = 400
+
+var _ = SIGDescribe("Servers with support for API chunking", func() {
+	f := framework.NewDefaultFramework("chunking")
+
+	It("should return chunks of results for list calls", func() {
+		ns := f.Namespace.Name
+		c := f.ClientSet
+		client := c.Core().PodTemplates(ns)
+
+		By("creating a large number of resources")
+		workqueue.Parallelize(20, numberOfTotalResources, func(i int) {
+			for tries := 3; tries >= 0; tries-- {
+				_, err := client.Create(&v1.PodTemplate{
+					ObjectMeta: metav1.ObjectMeta{
+						Name: fmt.Sprintf("template-%04d", i),
+					},
+					Template: v1.PodTemplateSpec{
+						Spec: v1.PodSpec{
+							Containers: []v1.Container{
+								{Name: "test", Image: "test2"},
+							},
+						},
+					},
+				})
+				if err == nil {
+					return
+				}
+				framework.Logf("Got an error creating template %d: %v", i, err)
+			}
+			Fail("Unable to create template %d, exiting", i)
+		})
+
+		By("retrieving those results in paged fashion several times")
+		for i := 0; i < 3; i++ {
+			opts := metav1.ListOptions{}
+			found := 0
+			var lastRV string
+			for {
+				opts.Limit = int64(rand.Int31n(numberOfTotalResources/10) + 1)
+				list, err := client.List(opts)
+				Expect(err).ToNot(HaveOccurred())
+				framework.Logf("Retrieved %d/%d results with rv %s and continue %s", len(list.Items), opts.Limit, list.ResourceVersion, list.Continue)
+
+				if len(lastRV) == 0 {
+					lastRV = list.ResourceVersion
+				}
+				if lastRV != list.ResourceVersion {
+					Expect(list.ResourceVersion).To(Equal(lastRV))
+				}
+				for _, item := range list.Items {
+					Expect(item.Name).To(Equal(fmt.Sprintf("template-%04d", found)))
+					found++
+				}
+				if len(list.Continue) == 0 {
+					break
+				}
+				opts.Continue = list.Continue
+			}
+			Expect(found).To(BeNumerically("==", numberOfTotalResources))
+		}
+
+		By("retrieving those results all at once")
+		list, err := client.List(metav1.ListOptions{Limit: numberOfTotalResources + 1})
+		Expect(err).ToNot(HaveOccurred())
+		Expect(list.Items).To(HaveLen(numberOfTotalResources))
+	})
+})