Adds support for discarding an item before restoring it

Within a RestoreItemAction, if the Execute function sets abandonItem
to true on the UpdatedItem before running it, then restoreResource
skips any remaining actions on this item, skips restoring this item
to the cluster, and continues on to the next item.

In the plugin Execute function, the following line would trigger
skipping, assuming input.Item is the object passed into
NewRestoreItemActionExecuteOutput on return:

	unstructured.SetNestedField(input.Item.UnstructuredContent(),
	                            true,
   	                            "abandonItem")

Author: sseago

pkg/restore/restore.go

@@ -700,6 +700,7 @@ func (ctx *context) restoreResource(resource, namespace, resourcePath string) (a
 		applicableActions = append(applicableActions, action)
 	}
 
+fileLoop:
 	for _, file := range files {
 		fullPath := filepath.Join(resourcePath, file.Name())
 		obj, err := ctx.unmarshal(fullPath)
@@ -847,6 +848,15 @@ func (ctx *context) restoreResource(resource, namespace, resourcePath string) (a
 				continue
 			}
 
+			abandon, err := abandonItem(executeOutput.UpdatedItem.(*unstructured.Unstructured))
+			if err != nil {
+				addToResult(&errs, namespace, fmt.Errorf("error preparing %s: %v", fullPath, err))
+				continue
+			}
+			if abandon {
+				ctx.log.Infof("Skipping restore of %s: %v because a registered plugin discarded it", obj.GroupVersionKind().Kind, name)
+				continue fileLoop
+			}
 			unstructuredObj, ok := executeOutput.UpdatedItem.(*unstructured.Unstructured)
 			if !ok {
 				addToResult(&errs, namespace, fmt.Errorf("%s: unexpected type %T", fullPath, executeOutput.UpdatedItem))
@@ -1046,6 +1056,20 @@ func isCompleted(obj *unstructured.Unstructured, groupResource schema.GroupResou
 	return false, nil
 }
 
+// abandonItem returns whether or not a RestoreItemAction has decided to skip restore
+// Used to identify whether or not an object should be restored.
+func abandonItem(obj *unstructured.Unstructured) (bool, error) {
+	abandon, found, err := unstructured.NestedBool(obj.UnstructuredContent(), "abandonItem")
+	if err != nil {
+		return false, errors.WithStack(err)
+	}
+	if found {
+		return abandon, nil
+	} else {
+		return false, nil
+	}
+}
+
 // unmarshal reads the specified file, unmarshals the JSON contained within it
 // and returns an Unstructured object.
 func (ctx *context) unmarshal(filePath string) (*unstructured.Unstructured, error) {