- Output for the `ScalingReplicaSet` event has changed from:
      Scaled <up|down> replica set <replica-set-name> to <new-value> from <old-value>
  to:
      Scaled <up|down> replica set <replica-set-name> from <old-value> to <new-value>. ([#125118](https://github.com/kubernetes/kubernetes/pull/125118), [@jsoref](https://github.com/jsoref)) [SIG Apps and CLI]

- Validation now requires new StatefulSets with a `.spec.serviceName` field value to pass DNS1123 validation. Previously created StatefulSets with an invalid `.spec.serviceName` field value could not create any pods, and should be deleted.

### API Machinery

- kube-apiserver: the `--runtime-config` flag now supports an `api/beta=false` value which disables all built-in REST API versions matching `v[0-9]+beta[0-9]+`. ([#84304](https://github.com/kubernetes/kubernetes/pull/84304), [@liggitt](https://github.com/liggitt))

  - `matchPolicy` default changed from `Exact` to `Equivalent` for v1
  - `timeout` default changed from `30s` to `10s` for v1
  - `sideEffects` default value is removed, and the field made required, and only `None` and `NoneOnDryRun` are permitted for v1
  - `admissionReviewVersions` default value is removed and the field made required for v1 (supported versions for AdmissionReview are `v1` and `v1beta1`)

  - `PriorityLevelConfiguration`: the `.spec.limited.nominalConcurrencyShares` field defaults to `30` only if the field is omitted (v1beta3 also defaulted an explicit `0` value to `30`). Specifying an explicit `0` value is not allowed in the `v1` version in v1.29 to ensure compatibility with `v1.28` API servers. In `v1.30`, explicit `0` values will be allowed in this field in the `v1` API.

### API Change

- Added (alpha) support for the `managedBy` field on Jobs. Jobs with a custom value of this field - any value other than `kubernetes.io/job-controller` - were skipped by the job controller, and their reconciliation was delegated to an external controller, indicated by the value of the field. Jobs that didn't have this field at all, or where the field value was the reserved string `kubernetes.io/job-controller`, were reconciled by the built-in job controller.

 - Fixes a bug defining a default value for a replicas field in a custom resource definition that has the scale subresource enabled ([#90019](https://github.com/kubernetes/kubernetes/pull/90019), [@liggitt](https://github.com/liggitt)) [SIG API Machinery, CLI, Cloud Provider, Cluster Lifecycle...

  kind.

#### Behavioral Changes

 - For all kinds in the API group version, a spec.selector default value is no longer
 available, because it's incompatible with `kubectl
 apply` and strategic merge patch. You must explicitly set the spec.selector value
 in your manifest. An object with a spec.selector value that does not match the labels in
 its spec.template is invalid.

- Kubeadm: during "kubeadm init/join/upgrade", always default the `cgroupDriver` value in the `KubeletConfiguration` to `systemd`, unless the user was explicit about the value....

- Ingress objects are now persisted in etcd using the `networking.k8s.io/v1beta1`...