## Changelog since v1.21.8

## Changes by Kind

### Feature

- Kubeadm: do not check if the `/etc/kubernetes/manifests` folder is empty on joining worker nodes during preflight ([#104942](https://github.com/kubernetes/kubernetes/pull/104942), [@SataQiu](https://github.com/SataQiu))

* Filter published OpenAPI schema by making nullable, required fields non-required in order to avoid kubectl to wrongly reject null values. ([#85722](https://github.com/kubernetes/kubernetes/pull/85722), [@sttts](https://github.com/sttts))

however, kubectl v1.21 and older do not support the new API for ephemeral containers.

    /** The key of the configuration. e.g. 0 */
    String QUERY_HIGHLIGHT_NO_MATCH_SIZE = "query.highlight.no.match.size";

    /** The key of the configuration. e.g. score */
    String QUERY_HIGHLIGHT_ORDER = "query.highlight.order";

    /** The key of the configuration. e.g. 256 */
    String QUERY_HIGHLIGHT_PHRASE_LIMIT = "query.highlight.phrase.limit";

    /** The key of the configuration. e.g. hl_content,digest */

- `kubeadm`: will now allow deploying a kubelet that is 3 versions older than the version of `kubeadm` (N-3). This aligns with the recent change made by SIG Architecture that extends the support skew between the control plane and kubelets. Tolerate this new kubelet skew for the commands `init`, `join` and `upgrade`. Note that if the `kubeadm` user applies a control plane version that is older than the `kubeadm` version (N-1 maximum) then the skew between the kubelet and control...

- `kubelet_pod_worker_latency_microseconds` -> `kubelet_pod_worker_duration_seconds`
- `kubelet_pod_start_latency_microseconds` -> `kubelet_pod_start_duration_seconds`
- `kubelet_cgroup_manager_latency_microseconds` -> `kubelet_cgroup_manager_duration_seconds`
- `kubelet_pod_worker_start_latency_microseconds` -> `kubelet_pod_worker_start_duration_seconds`

- The AnyVolumeDataSource feature is now beta, and the feature gate is enabled by default. In order to provide user feedback on PVCs with data sources, deployers must install the VolumePopulators CRD and the data-source-validator controller. ([#108736](https://github.com/kubernetes/kubernetes/pull/108736), [@bswartz](https://github.com/bswartz))...

### Failing Test

- Fixes the `should receive events on concurrent watches in same order` conformance test to work properly on clusters that auto-create additional configmaps in namespaces ([#101950](https://github.com/kubernetes/kubernetes/pull/101950), [@liggitt](https://github.com/liggitt)) [SIG API Machinery and Testing]

      - `kubelet_pod_worker_latency_microseconds` -> `kubelet_pod_worker_duration_seconds`
      - `kubelet_pod_start_latency_microseconds` -> `kubelet_pod_start_duration_seconds`
      - `kubelet_cgroup_manager_latency_microseconds` -> `kubelet_cgroup_manager_duration_seconds`
      - `kubelet_pod_worker_start_latency_microseconds` -> `kubelet_pod_worker_start_duration_seconds`