* Action required: validation rule on metadata.initializers.pending[x].name is tightened. The initializer name needs to contain at least three segments separated by dots. If you create objects with pending initializers, (i.e., not relying on apiserver adding pending initializers according to initializerconfiguration), you need to update the initializer name in existing objects and in configuration files to comply...

- Added kubelet metrics to track the memory manager allocation and pinning. ([#121778](https://github.com/kubernetes/kubernetes/pull/121778), [@Tal-or](https://github.com/Tal-or))

- Fixed bug where dry run message was not printed when running `kubectl label` with `--dry-run` flag. ([#111571](https://github.com/kubernetes/kubernetes/pull/111571), [@brianpursley](https://github.com/brianpursley))

enabled.([#51436](https://github.com/kubernetes/kubernetes/pull/51436))

* [Action required] The validation rule for metadata.initializers.pending[x].name is tightened. The initializer name must contain at least three segments, separated by dots. You can create objects with pending initializers and not rely on the API server to add pending initializers according to `initializerConfiguration`. If you do so, update the initializer name in the existing objects and the configuration files to...

Pruning is activated by setting `spec.preserveUnknownFields: false` in the CustomResourceDefinition. A future apiextensions.k8s.io/v1 variant of CRDs will enforce pruning.

Pruning requires that CRD developer provides complete, structural validation schemas, either at the top-level or for all versions of the CRD.

### Other (Cleanup or Flake)

- Building Kubernetes is now implemented by running a pre-built container image directly, without running rsyncd, and is substantially simplified. ([#134510](https://github.com/kubernetes/kubernetes/pull/134510), [@BenTheElder](https://github.com/BenTheElder)) [SIG Release and Testing]

- Kube-apiserver: Promoted the `ExternalServiceAccountTokenSigner` feature to beta, which enabled external signing of service account tokens and fetching of public verifying keys. This was accomplished by enabling the beta `ExternalServiceAccountTokenSigner` feature gate and specifying the `--service-account-signing-endpoint` flag. The flag value could either be the path to a Unix domain socket on the filesystem, or be prefixed with @ to indicate a Unix domain...

deserialization, which fails if the config file contains duplicate or unknown fields. This protects against accidentally running with config files that are malformed, mis-indented, or have typos in field names, and getting unexpected behavior. When `--encryption-provider-config-automatic-reload` is used, new encryption config files that contain typos after the kube-apiserver is running are treated as invalid and the last valid config is used. ([#124912](https://github.com/kubernetes/kubernetes/pull/124912),...

* Fixes bug finding master replicas in GCE when running multiple Kubernetes clusters. ([#58561](https://github.com/kubernetes/kubernetes/pull/58561), [@jesseshieh](https://github.com/jesseshieh))

  - [Major Themes](#major-themes)
    - [Dockershim Removed from kubelet](#dockershim-removed-from-kubelet)
    - [Beta APIs Off by Default](#beta-apis-off-by-default)
    - [Signing Release Artifacts](#signing-release-artifacts)
    - [OpenAPI v3](#openapi-v3)
    - [Storage Capacity and Volume Expansion Are Generally Available](#storage-capacity-and-volume-expansion-are-generally-available)