⚠️ Fakeclient: Fix status handling

This change fixes the status handling of the fake status client by

* Adding a new `WithStatusSubresource` option and pre-poluating it with
  all in-tree resources that have a status subresource
* Making its `Update` and `Patch` not change the status of any such
  resource
* Making its status client `Update` and `Patch` only change the status
  for any such resources

Since this was completely broken before in that both non-status and
status Update/Patch would always update everything and the status
resoruces get pre-populated, this is a breaking change. Any test that
relied on the previous behavior would pass incorrectly though, as it
didn't match what the Kubernetes API does.

Author: alvaroaleman

pkg/client/fake/client.go

@@ -17,11 +17,13 @@ limitations under the License.
 package fake
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"reflect"
+	"runtime/debug"
 	"strconv"
 	"strings"
 	"sync"
@@ -35,6 +37,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	utilrand "k8s.io/apimachinery/pkg/util/rand"
+	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	"k8s.io/apimachinery/pkg/watch"
 	"k8s.io/client-go/kubernetes/scheme"
@@ -48,13 +51,15 @@ import (
 
 type versionedTracker struct {
 	testing.ObjectTracker
-	scheme *runtime.Scheme
+	scheme                *runtime.Scheme
+	withStatusSubresource sets.Set[schema.GroupVersionKind]
 }
 
 type fakeClient struct {
-	tracker    versionedTracker
-	scheme     *runtime.Scheme
-	restMapper meta.RESTMapper
+	tracker               versionedTracker
+	scheme                *runtime.Scheme
+	restMapper            meta.RESTMapper
+	withStatusSubresource sets.Set[schema.GroupVersionKind]
 
 	// indexes maps each GroupVersionKind (GVK) to the indexes registered for that GVK.
 	// The inner map maps from index name to IndexerFunc.
@@ -95,12 +100,13 @@ func NewClientBuilder() *ClientBuilder {
 
 // ClientBuilder builds a fake client.
 type ClientBuilder struct {
-	scheme             *runtime.Scheme
-	restMapper         meta.RESTMapper
-	initObject         []client.Object
-	initLists          []client.ObjectList
-	initRuntimeObjects []runtime.Object
-	objectTracker      testing.ObjectTracker
+	scheme                *runtime.Scheme
+	restMapper            meta.RESTMapper
+	initObject            []client.Object
+	initLists             []client.ObjectList
+	initRuntimeObjects    []runtime.Object
+	withStatusSubresource []client.Object
+	objectTracker         testing.ObjectTracker
 
 	// indexes maps each GroupVersionKind (GVK) to the indexes registered for that GVK.
 	// The inner map maps from index name to IndexerFunc.
@@ -185,6 +191,13 @@ func (f *ClientBuilder) WithIndex(obj runtime.Object, field string, extractValue
 	return f
 }
 
+// WithStatusSubresource configures the passed object with a status subresource, which means
+// calls to Update and Patch will not alters its status.
+func (f *ClientBuilder) WithStatusSubresource(o ...client.Object) *ClientBuilder {
+	f.withStatusSubresource = append(f.withStatusSubresource, o...)
+	return f
+}
+
 // Build builds and returns a new fake client.
 func (f *ClientBuilder) Build() client.WithWatch {
 	if f.scheme == nil {
@@ -196,10 +209,19 @@ func (f *ClientBuilder) Build() client.WithWatch {
 
 	var tracker versionedTracker
 
+	withStatusSubResource := sets.New(inTreeResourcesWithStatus()...)
+	for _, o := range f.withStatusSubresource {
+		gvk, err := apiutil.GVKForObject(o, f.scheme)
+		if err != nil {
+			panic(fmt.Errorf("failed to get gvk for object %T: %w", withStatusSubResource, err))
+		}
+		withStatusSubResource.Insert(gvk)
+	}
+
 	if f.objectTracker == nil {
-		tracker = versionedTracker{ObjectTracker: testing.NewObjectTracker(f.scheme, scheme.Codecs.UniversalDecoder()), scheme: f.scheme}
+		tracker = versionedTracker{ObjectTracker: testing.NewObjectTracker(f.scheme, scheme.Codecs.UniversalDecoder()), scheme: f.scheme, withStatusSubresource: withStatusSubResource}
 	} else {
-		tracker = versionedTracker{ObjectTracker: f.objectTracker, scheme: f.scheme}
+		tracker = versionedTracker{ObjectTracker: f.objectTracker, scheme: f.scheme, withStatusSubresource: withStatusSubResource}
 	}
 
 	for _, obj := range f.initObject {
@@ -217,11 +239,13 @@ func (f *ClientBuilder) Build() client.WithWatch {
 			panic(fmt.Errorf("failed to add runtime object %v to fake client: %w", obj, err))
 		}
 	}
+
 	return &fakeClient{
-		tracker:    tracker,
-		scheme:     f.scheme,
-		restMapper: f.restMapper,
-		indexes:    f.indexes,
+		tracker:               tracker,
+		scheme:                f.scheme,
+		restMapper:            f.restMapper,
+		indexes:               f.indexes,
+		withStatusSubresource: withStatusSubResource,
 	}
 }
 
@@ -318,6 +342,16 @@ func convertFromUnstructuredIfNecessary(s *runtime.Scheme, o runtime.Object) (ru
 }
 
 func (t versionedTracker) Update(gvr schema.GroupVersionResource, obj runtime.Object, ns string) error {
+	isSubResource := false
+	// We apply patches using a client-go reaction that ends up calling the trackers Update. As we can't change
+	// that reaction, we use the callstack to figure out if this originated from the status client.
+	if bytes.Contains(debug.Stack(), []byte("sigs.k8s.io/controller-runtime/pkg/client/fake.(*fakeSubResourceClient).Patch")) {
+		isSubResource = true
+	}
+	return t.update(gvr, obj, ns, isSubResource)
+}
+
+func (t versionedTracker) update(gvr schema.GroupVersionResource, obj runtime.Object, ns string, isStatus bool) error {
 	accessor, err := meta.Accessor(obj)
 	if err != nil {
 		return fmt.Errorf("failed to get accessor for object: %w", err)
@@ -348,6 +382,19 @@ func (t versionedTracker) Update(gvr schema.GroupVersionResource, obj runtime.Ob
 		return err
 	}
 
+	if t.withStatusSubresource.Has(gvk) {
+		if isStatus { // copy everything but status and metadata.ResourceVersion from original object
+			if err := copyNonStatusFrom(oldObject, obj); err != nil {
+				return fmt.Errorf("failed to copy non-status field for object with status subresouce: %w", err)
+			}
+
+		} else { // copy status from original object
+			if err := copyStatusFrom(oldObject, obj); err != nil {
+				return fmt.Errorf("failed to copy the status for object with status subresource: %w", err)
+			}
+		}
+	}
+
 	oldAccessor, err := meta.Accessor(oldObject)
 	if err != nil {
 		return err
@@ -689,6 +736,10 @@ func (c *fakeClient) DeleteAllOf(ctx context.Context, obj client.Object, opts ..
 }
 
 func (c *fakeClient) Update(ctx context.Context, obj client.Object, opts ...client.UpdateOption) error {
+	return c.update(obj, false, opts...)
+}
+
+func (c *fakeClient) update(obj client.Object, isStatus bool, opts ...client.UpdateOption) error {
 	updateOptions := &client.UpdateOptions{}
 	updateOptions.ApplyOptions(opts)
 
@@ -706,10 +757,14 @@ func (c *fakeClient) Update(ctx context.Context, obj client.Object, opts ...clie
 	if err != nil {
 		return err
 	}
-	return c.tracker.Update(gvr, obj, accessor.GetNamespace())
+	return c.tracker.update(gvr, obj, accessor.GetNamespace(), isStatus)
 }
 
 func (c *fakeClient) Patch(ctx context.Context, obj client.Object, patch client.Patch, opts ...client.PatchOption) error {
+	return c.patch(obj, patch, opts...)
+}
+
+func (c *fakeClient) patch(obj client.Object, patch client.Patch, opts ...client.PatchOption) error {
 	patchOptions := &client.PatchOptions{}
 	patchOptions.ApplyOptions(opts)
 
@@ -732,6 +787,11 @@ func (c *fakeClient) Patch(ctx context.Context, obj client.Object, patch client.
 		return err
 	}
 
+	gvk, err := apiutil.GVKForObject(obj, c.scheme)
+	if err != nil {
+		return err
+	}
+
 	reaction := testing.ObjectReaction(c.tracker)
 	handled, o, err := reaction(testing.NewPatchAction(gvr, accessor.GetNamespace(), accessor.GetName(), patch.Type(), data))
 	if err != nil {
@@ -740,11 +800,6 @@ func (c *fakeClient) Patch(ctx context.Context, obj client.Object, patch client.
 	if !handled {
 		panic("tracker could not handle patch method")
 	}
-
-	gvk, err := apiutil.GVKForObject(obj, c.scheme)
-	if err != nil {
-		return err
-	}
 	ta, err := meta.TypeAccessor(o)
 	if err != nil {
 		return err
@@ -762,6 +817,97 @@ func (c *fakeClient) Patch(ctx context.Context, obj client.Object, patch client.
 	return err
 }
 
+func copyNonStatusFrom(old, new runtime.Object) error {
+	newClientObject, ok := new.(client.Object)
+	if !ok {
+		return fmt.Errorf("%T is not a client.Object", new)
+	}
+	// The only thing other than status we have to retain
+	rv := newClientObject.GetResourceVersion()
+
+	oldMapStringAny, err := toMapStringAny(old)
+	if err != nil {
+		return fmt.Errorf("failed to convert old to *unstructured.Unstructured: %w", err)
+	}
+	newMapStringAny, err := toMapStringAny(new)
+	if err != nil {
+		return fmt.Errorf("failed to convert new to *unststructured.Unstructured: %w", err)
+	}
+
+	// delete everything other than status in case it has fields that were not present in
+	// the old object
+	for k := range newMapStringAny {
+		if k != "status" {
+			delete(newMapStringAny, k)
+		}
+	}
+	// copy everything other than status from the old object
+	for k := range oldMapStringAny {
+		if k != "status" {
+			newMapStringAny[k] = oldMapStringAny[k]
+		}
+	}
+
+	newClientObject.SetResourceVersion(rv)
+
+	if err := fromMapStringAny(newMapStringAny, new); err != nil {
+		return fmt.Errorf("failed to convert back from map[string]any: %w", err)
+	}
+	return nil
+}
+
+// copyStatusFrom copies the status from old into new
+func copyStatusFrom(old, new runtime.Object) error {
+	oldMapStringAny, err := toMapStringAny(old)
+	if err != nil {
+		return fmt.Errorf("failed to convert old to *unstructured.Unstructured: %w", err)
+	}
+	newMapStringAny, err := toMapStringAny(new)
+	if err != nil {
+		return fmt.Errorf("failed to convert new to *unststructured.Unstructured: %w", err)
+	}
+
+	newMapStringAny["status"] = oldMapStringAny["status"]
+
+	if err := fromMapStringAny(newMapStringAny, new); err != nil {
+		return fmt.Errorf("failed to convert back from map[string]any: %w", err)
+	}
+
+	return nil
+}
+
+func toMapStringAny(obj runtime.Object) (map[string]any, error) {
+	if unstructured, isUnstructured := obj.(*unstructured.Unstructured); isUnstructured {
+		return unstructured.Object, nil
+	}
+
+	serialized, err := json.Marshal(obj)
+	if err != nil {
+		return nil, err
+	}
+
+	u := map[string]any{}
+	return u, json.Unmarshal(serialized, &u)
+}
+
+func fromMapStringAny(u map[string]any, target runtime.Object) error {
+	if targetUnstructured, isUnstructured := target.(*unstructured.Unstructured); isUnstructured {
+		targetUnstructured.Object = u
+		return nil
+	}
+
+	serialized, err := json.Marshal(u)
+	if err != nil {
+		return fmt.Errorf("failed to serialize: %w", err)
+	}
+
+	if err := json.Unmarshal(serialized, &target); err != nil {
+		return fmt.Errorf("failed to deserialize: %w", err)
+	}
+
+	return nil
+}
+
 func (c *fakeClient) Status() client.SubResourceWriter {
 	return c.SubResource("status")
 }
@@ -809,22 +955,17 @@ func (sw *fakeSubResourceClient) Create(ctx context.Context, obj client.Object,
 }
 
 func (sw *fakeSubResourceClient) Update(ctx context.Context, obj client.Object, opts ...client.SubResourceUpdateOption) error {
-	// TODO(droot): This results in full update of the obj (spec + subresources). Need
-	// a way to update subresource only.
 	updateOptions := client.SubResourceUpdateOptions{}
 	updateOptions.ApplyOptions(opts)
 
 	body := obj
 	if updateOptions.SubResourceBody != nil {
 		body = updateOptions.SubResourceBody
 	}
-	return sw.client.Update(ctx, body, &updateOptions.UpdateOptions)
+	return sw.client.update(body, true, &updateOptions.UpdateOptions)
 }
 
 func (sw *fakeSubResourceClient) Patch(ctx context.Context, obj client.Object, patch client.Patch, opts ...client.SubResourcePatchOption) error {
-	// TODO(droot): This results in full update of the obj (spec + subresources). Need
-	// a way to update subresource only.
-
 	patchOptions := client.SubResourcePatchOptions{}
 	patchOptions.ApplyOptions(opts)
 
@@ -833,7 +974,7 @@ func (sw *fakeSubResourceClient) Patch(ctx context.Context, obj client.Object, p
 		body = patchOptions.SubResourceBody
 	}
 
-	return sw.client.Patch(ctx, body, patch, &patchOptions.PatchOptions)
+	return sw.client.patch(body, patch, &patchOptions.PatchOptions)
 }
 
 func allowsUnconditionalUpdate(gvk schema.GroupVersionKind) bool {
@@ -933,6 +1074,42 @@ func allowsCreateOnUpdate(gvk schema.GroupVersionKind) bool {
 	return false
 }
 
+func inTreeResourcesWithStatus() []schema.GroupVersionKind {
+	return []schema.GroupVersionKind{
+		{Version: "v1", Kind: "Namespace"},
+		{Version: "v1", Kind: "Node"},
+		{Version: "v1", Kind: "PersistentVolumeClaim"},
+		{Version: "v1", Kind: "PersistentVolume"},
+		{Version: "v1", Kind: "Pod"},
+		{Version: "v1", Kind: "ReplicationController"},
+		{Version: "v1", Kind: "Service"},
+
+		{Group: "apps", Version: "v1", Kind: "Deployment"},
+		{Group: "apps", Version: "v1", Kind: "DaemonSet"},
+		{Group: "apps", Version: "v1", Kind: "ReplicaSet"},
+		{Group: "apps", Version: "v1", Kind: "StatefulSet"},
+
+		{Group: "autoscaling", Version: "v1", Kind: "HorizontalPodAutoscaler"},
+
+		{Group: "batch", Version: "v1", Kind: "CronJob"},
+		{Group: "batch", Version: "v1", Kind: "Job"},
+
+		{Group: "certificates.k8s.io", Version: "v1", Kind: "CertificateSigningRequest"},
+
+		{Group: "networking.k8s.io", Version: "v1", Kind: "Ingress"},
+		{Group: "networking.k8s.io", Version: "v1", Kind: "NetworkPolicy"},
+
+		{Group: "policy", Version: "v1", Kind: "PodDisruptionBudget"},
+
+		{Group: "storage.k8s.io", Version: "v1", Kind: "VolumeAttachment"},
+
+		{Group: "apiextensions.k8s.io", Version: "v1", Kind: "CustomResourceDefinition"},
+
+		{Group: "flowcontrol.apiserver.k8s.io", Version: "v1beta2", Kind: "FlowSchema"},
+		{Group: "flowcontrol.apiserver.k8s.io", Version: "v1beta2", Kind: "PriorityLevelConfiguration"},
+	}
+}
+
 // zero zeros the value of a pointer.
 func zero(x interface{}) {
 	if x == nil {