- [CustomResourceDefinitions Pruning](#customresourcedefinitions-pruning)
    - [CustomResourceDefinition Defaulting](#customresourcedefinition-defaulting)
    - [CustomResourceDefinition OpenAPI Publishing](#customresourcedefinition-openapi-publishing)
  - [Cluster Lifecycle Stability and Usability Improvements](#cluster-lifecycle-stability-and-usability-improvements)

  - When registering with a 1.17+ API server, a CustomResourceDefinition conversion webhook can now request that only `v1` ConversionReview requests be sent to them. Previously, conversion webhooks were required to support receiving `v1beta1` ConversionReview requests as well for compatibility with API servers...

    The `apiextensions.k8s.io/v1beta1` version of `CustomResourceDefinition` is deprecated and will no longer be served in v1.19. ([#79604](https://github.com/kubernetes/kubernetes/pull/79604), [@liggitt](https://github.com/liggitt))

- CustomResourceDefinition schemas that use `x-kubernetes-list-map-keys` to specify properties that uniquely identify list items must make those properties required or have a default value, to ensure those properties are present for all list items. See https://kub...

- Introduced OpenAPI format support for `k8s-short-name` and `k8s-long-name` in CustomResourceDefinition schemas. ([#132504](https://github.com/kubernetes/kubernetes/pull/132504), [@jpbetz](https://github.com/jpbetz)) [SIG API Machinery, Architecture, Auth, CLI, Cloud Provider, Cluster Lifecycle, Instrumentation, Network, Node, Scheduling and...

- Alpha support for field selectors on custom resources has been added. With the `CustomResourceFieldSelectors` feature gate enabled, the CustomResourceDefinition API now allows specifying `selectableFields`. Listing a field there enables filtering custom resources for that CustomResourceDefinition in list or watch requests. ([#122717](https://github.com/kubernetes/kubernetes/pull/122717), [@jpbetz](https://github.com/jpbetz))

* The deprecated `ThirdPartyResource` (TPR) API was removed.
  To avoid losing your TPR data, [migrate to CustomResourceDefinition](https://kubernetes.io/docs/tasks/access-kubernetes-api/migrate-third-party-resource/).

* The following deprecated flags were removed from `kube-controller-manager`:

- Added CEL runtime cost calculation into ValidatingAdmissionPolicy, matching the evaluation cost
  restrictions that already apply to CustomResourceDefinition.
  If rule evaluation uses more compute than the limit, the API server aborts the evaluation and the
  admission check that was being performed is aborted; the `failurePolicy` for the ValidatingAdmissionPolicy

* 'cj' has been added as a shortname for CronJobs, as in `kubectl get cj` ([#59499](https://github.com/kubernetes/kubernetes/pull/59499), [@soltysh](https://github.com/soltysh))

* `crds` has been added as a shortname for CustomResourceDefinition, as in `kubectl get crds` ([#59061](https://github.com/kubernetes/kubernetes/pull/59061), [@nikhita](https://github.com/nikhita))

* Set node external IP for azure node when disabling UseInstanceMetadata ([#60959](https://github.com/kubernetes/kubernetes/pull/60959), [@feiskyer](https://github.com/feiskyer))
* Fixes potential deadlock when deleting CustomResourceDefinition for custom resources with finalizers ([#60542](https://github.com/kubernetes/kubernetes/pull/60542), [@liggitt](https://github.com/liggitt))