Merge pull request #60021 from nikhita/sample-controller-subresources

Automatic merge from submit-queue (batch tested with PRs 60102, 59970, 60021, 62011, 62080). 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>.

sample-controller: add status subresource support

Builds on top of https://github.com/kubernetes/kubernetes/pull/55168.

**DO NOT MERGE** until https://github.com/kubernetes/kubernetes/pull/55168 is merged. Adding a hold.
/hold

Update: It is now merged! 🎉

This PR:

- Adds an example to show how to use the `/status` subresource with custom resources.
- Generates `UpdateStatus` for the `Foo` resource.
- Updates the comment in the controller to mention that `UpdateStatus` can now be used. Note: this is not enabled by default because subresources require the feature gate to be enabled and are not on by default.
- Updates the README to add feature gate information and examples for `CustomResourceSubresources`.
- Updates the README to remove feature gate information for CRD validation since the current example uses `apps/v1` deployments (and thus requires v1.9 anyway).

**Release note**:

```release-note
NONE
```

/assign sttts munnerz

Kubernetes-commit: 7bde13f191f0791a87fe5e2575feb3d4849de536

vendor/k8s.io/apimachinery/pkg/apis/meta/v1/unstructured/unstructured.go

@@ -82,7 +82,7 @@ func (obj *Unstructured) EachListItem(fn func(runtime.Object) error) error {
 
 func (obj *Unstructured) UnstructuredContent() map[string]interface{} {
 	if obj.Object == nil {
-		obj.Object = make(map[string]interface{})
+		return make(map[string]interface{})
 	}
 	return obj.Object
 }

vendor/k8s.io/apimachinery/pkg/apis/meta/v1/unstructured/unstructured_list.go

@@ -53,19 +53,18 @@ func (u *UnstructuredList) EachListItem(fn func(runtime.Object) error) error {
 }
 
 // UnstructuredContent returns a map contain an overlay of the Items field onto
-// the Object field. Items always overwrites overlay. Changing "items" in the
-// returned object will affect items in the underlying Items field, but changing
-// the "items" slice itself will have no effect.
-// TODO: expose SetUnstructuredContent on runtime.Unstructured that allows
-// items to be changed.
+// the Object field. Items always overwrites overlay.
 func (u *UnstructuredList) UnstructuredContent() map[string]interface{} {
-	out := u.Object
-	if out == nil {
-		out = make(map[string]interface{})
+	out := make(map[string]interface{}, len(u.Object)+1)
+
+	// shallow copy every property
+	for k, v := range u.Object {
+		out[k] = v
 	}
+
 	items := make([]interface{}, len(u.Items))
 	for i, item := range u.Items {
-		items[i] = item.Object
+		items[i] = item.UnstructuredContent()
 	}
 	out["items"] = items
 	return out

vendor/k8s.io/apimachinery/pkg/runtime/converter.go

@@ -411,8 +411,7 @@ func (c *unstructuredConverter) ToUnstructured(obj interface{}) (map[string]inte
 	var u map[string]interface{}
 	var err error
 	if unstr, ok := obj.(Unstructured); ok {
-		// UnstructuredContent() mutates the object so we need to make a copy first
-		u = unstr.DeepCopyObject().(Unstructured).UnstructuredContent()
+		u = unstr.UnstructuredContent()
 	} else {
 		t := reflect.TypeOf(obj)
 		value := reflect.ValueOf(obj)
@@ -449,12 +448,20 @@ func DeepCopyJSON(x map[string]interface{}) map[string]interface{} {
 func DeepCopyJSONValue(x interface{}) interface{} {
 	switch x := x.(type) {
 	case map[string]interface{}:
+		if x == nil {
+			// Typed nil - an interface{} that contains a type map[string]interface{} with a value of nil
+			return x
+		}
 		clone := make(map[string]interface{}, len(x))
 		for k, v := range x {
 			clone[k] = DeepCopyJSONValue(v)
 		}
 		return clone
 	case []interface{}:
+		if x == nil {
+			// Typed nil - an interface{} that contains a type []interface{} with a value of nil
+			return x
+		}
 		clone := make([]interface{}, len(x))
 		for i, v := range x {
 			clone[i] = DeepCopyJSONValue(v)

vendor/k8s.io/apimachinery/pkg/runtime/interfaces.go

@@ -234,9 +234,9 @@ type Object interface {
 // to JSON allowed.
 type Unstructured interface {
 	Object
-	// UnstructuredContent returns a non-nil, mutable map of the contents of this object. Values may be
+	// UnstructuredContent returns a non-nil map with this object's contents. Values may be
 	// []interface{}, map[string]interface{}, or any primitive type. Contents are typically serialized to
-	// and from JSON.
+	// and from JSON. SetUnstructuredContent should be used to mutate the contents.
 	UnstructuredContent() map[string]interface{}
 	// SetUnstructuredContent updates the object content to match the provided map.
 	SetUnstructuredContent(map[string]interface{})

vendor/k8s.io/apimachinery/pkg/util/strategicpatch/patch.go

@@ -880,6 +880,29 @@ func StrategicMergeMapPatchUsingLookupPatchMeta(original, patch JSONMap, schema
 	return mergeMap(original, patch, schema, mergeOptions)
 }
 
+// MergeStrategicMergeMapPatchUsingLookupPatchMeta merges strategic merge
+// patches retaining `null` fields and parallel lists. If 2 patches change the
+// same fields and the latter one will override the former one. If you don't
+// want that happen, you need to run func MergingMapsHaveConflicts before
+// merging these patches. Applying the resulting merged merge patch to a JSONMap
+// yields the same as merging each strategic merge patch to the JSONMap in
+// succession.
+func MergeStrategicMergeMapPatchUsingLookupPatchMeta(schema LookupPatchMeta, patches ...JSONMap) (JSONMap, error) {
+	mergeOptions := MergeOptions{
+		MergeParallelList:    false,
+		IgnoreUnmatchedNulls: false,
+	}
+	merged := JSONMap{}
+	var err error
+	for _, patch := range patches {
+		merged, err = mergeMap(merged, patch, schema, mergeOptions)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return merged, nil
+}
+
 // handleDirectiveInMergeMap handles the patch directive when merging 2 maps.
 func handleDirectiveInMergeMap(directive interface{}, patch map[string]interface{}) (map[string]interface{}, error) {
 	if directive == replaceDirective {