kubernetes/staging/src/k8s.io/apimachinery/pkg/util/managedfields/extract.go

// ExtractInto extracts the applied configuration state from object for fieldManager
// into applyConfiguration. If no managed fields are found for the given fieldManager,
// no error is returned, but applyConfiguration is left unpopulated. It is possible
// that no managed fields were found for the fieldManager because other field managers
// have taken ownership of all the fields previously owned by the fieldManager. It is
// also possible the fieldManager never owned fields.
//
// The provided object MUST bo a root resource object since subresource objects
// do not contain their own managed fields. For example, an autoscaling.Scale
// object read from a "scale" subresource does not have any managed fields and so
// cannot be used as the object.
//
// If the fields of a subresource are a subset of the fields of the root object,
// and their field paths and types are exactly the same, then ExtractInto can be
// called with the root resource as the object and the subresource as the
// applyConfiguration. This works for "status", obviously, because status is
// represented by the exact same object as the root resource. This does NOT
// work, for example, with the "scale" subresources of Deployment, ReplicaSet and
// StatefulSet. While the spec.replicas, status.replicas fields are in the same
// exact field path locations as they are in autoscaling.Scale, the selector
// fields are in different locations, and are a different type.
func ExtractInto(object runtime.Object, objectType typed.ParseableType, fieldManager string, applyConfiguration interface{ … }

func findManagedFields(accessor metav1.Object, fieldManager string, subresource string) (metav1.ManagedFieldsEntry, bool) { … }

func toTyped(obj runtime.Object, objectType typed.ParseableType) (*typed.TypedValue, error) { … }