GC fallback to jsonmerge patch when SMP is not supported

pkg/controller/garbagecollector/patch.go

@@ -21,12 +21,16 @@ import (
 	"fmt"
 	"strings"
 
+	"k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/kubernetes/pkg/controller/garbagecollector/metaonly"
 )
 
-func deleteOwnerRefPatch(dependentUID types.UID, ownerUIDs ...types.UID) []byte {
+func deleteOwnerRefStrategicMergePatch(dependentUID types.UID, ownerUIDs ...types.UID) []byte {
 	var pieces []string
 	for _, ownerUID := range ownerUIDs {
 		pieces = append(pieces, fmt.Sprintf(`{"$patch":"delete","uid":"%s"}`, ownerUID))
@@ -35,9 +39,97 @@ func deleteOwnerRefPatch(dependentUID types.UID, ownerUIDs ...types.UID) []byte
 	return []byte(patch)
 }
 
-// generate a patch that unsets the BlockOwnerDeletion field of all
+// getMetadata tries getting object metadata from local cache, and sends GET request to apiserver when
+// local cache is not available or not latest.
+func (gc *GarbageCollector) getMetadata(apiVersion, kind, namespace, name string) (metav1.Object, error) {
+	apiResource, _, err := gc.apiResource(apiVersion, kind)
+	if err != nil {
+		return nil, err
+	}
+	gc.dependencyGraphBuilder.monitorLock.RLock()
+	defer gc.dependencyGraphBuilder.monitorLock.RUnlock()
+	m, ok := gc.dependencyGraphBuilder.monitors[apiResource]
+	if !ok || m == nil {
+		// If local cache doesn't exist for mapping.Resource, send a GET request to API server
+		return gc.dynamicClient.Resource(apiResource).Namespace(namespace).Get(name, metav1.GetOptions{})
+	}
+	key := name
+	if len(namespace) != 0 {
+		key = namespace + "/" + name
+	}
+	raw, exist, err := m.store.GetByKey(key)
+	if err != nil {
+		return nil, err
+	}
+	if !exist {
+		// If local cache doesn't contain the object, send a GET request to API server
+		return gc.dynamicClient.Resource(apiResource).Namespace(namespace).Get(name, metav1.GetOptions{})
+	}
+	obj, ok := raw.(runtime.Object)
+	if !ok {
+		return nil, fmt.Errorf("expect a runtime.Object, got %v", raw)
+	}
+	return meta.Accessor(obj)
+}
+
+type objectForPatch struct {
+	ObjectMetaForPatch `json:"metadata"`
+}
+
+type ObjectMetaForPatch struct {
+	ResourceVersion string                  `json:"resourceVersion"`
+	OwnerReferences []metav1.OwnerReference `json:"ownerReferences"`
+}
+
+// jsonMergePatchFunc defines the interface for functions that construct json merge patches that manipulate
+// owner reference array.
+type jsonMergePatchFunc func(*node) ([]byte, error)
+
+// patch tries strategic merge patch on item first, and if SMP is not supported, it fallbacks to JSON merge
+// patch.
+func (gc *GarbageCollector) patch(item *node, smp []byte, jmp jsonMergePatchFunc) (*unstructured.Unstructured, error) {
+	smpResult, err := gc.patchObject(item.identity, smp, types.StrategicMergePatchType)
+	if err == nil {
+		return smpResult, nil
+	}
+	if !errors.IsUnsupportedMediaType(err) {
+		return nil, err
+	}
+	// StrategicMergePatch is not supported, use JSON merge patch instead
+	patch, err := jmp(item)
+	if err != nil {
+		return nil, err
+	}
+	return gc.patchObject(item.identity, patch, types.MergePatchType)
+}
+
+// Returns JSON merge patch that removes the ownerReferences matching ownerUIDs.
+func (gc *GarbageCollector) deleteOwnerRefJSONMergePatch(item *node, ownerUIDs ...types.UID) ([]byte, error) {
+	accessor, err := gc.getMetadata(item.identity.APIVersion, item.identity.Kind, item.identity.Namespace, item.identity.Name)
+	if err != nil {
+		return nil, err
+	}
+	expectedObjectMeta := ObjectMetaForPatch{}
+	expectedObjectMeta.ResourceVersion = accessor.GetResourceVersion()
+	refs := accessor.GetOwnerReferences()
+	for _, ref := range refs {
+		var skip bool
+		for _, ownerUID := range ownerUIDs {
+			if ref.UID == ownerUID {
+				skip = true
+				break
+			}
+		}
+		if !skip {
+			expectedObjectMeta.OwnerReferences = append(expectedObjectMeta.OwnerReferences, ref)
+		}
+	}
+	return json.Marshal(objectForPatch{expectedObjectMeta})
+}
+
+// Generate a patch that unsets the BlockOwnerDeletion field of all
 // ownerReferences of node.
-func (n *node) patchToUnblockOwnerReferences() ([]byte, error) {
+func (n *node) unblockOwnerReferencesStrategicMergePatch() ([]byte, error) {
 	var dummy metaonly.MetadataOnlyObject
 	var blockingRefs []metav1.OwnerReference
 	falseVar := false
@@ -52,3 +144,22 @@ func (n *node) patchToUnblockOwnerReferences() ([]byte, error) {
 	dummy.ObjectMeta.UID = n.identity.UID
 	return json.Marshal(dummy)
 }
+
+// Generate a JSON merge patch that unsets the BlockOwnerDeletion field of all
+// ownerReferences of node.
+func (gc *GarbageCollector) unblockOwnerReferencesJSONMergePatch(n *node) ([]byte, error) {
+	accessor, err := gc.getMetadata(n.identity.APIVersion, n.identity.Kind, n.identity.Namespace, n.identity.Name)
+	if err != nil {
+		return nil, err
+	}
+	expectedObjectMeta := ObjectMetaForPatch{}
+	expectedObjectMeta.ResourceVersion = accessor.GetResourceVersion()
+	var expectedOwners []metav1.OwnerReference
+	falseVar := false
+	for _, owner := range n.owners {
+		owner.BlockOwnerDeletion = &falseVar
+		expectedOwners = append(expectedOwners, owner)
+	}
+	expectedObjectMeta.OwnerReferences = expectedOwners
+	return json.Marshal(objectForPatch{expectedObjectMeta})
+}