var v *T           // v has value nil, static type *T
x = 42             // x has value 42 and dynamic type int
x = v              // x has value (*T)(nil) and dynamic type *T
</pre>

<p>
A variable's value is retrieved by referring to the variable in an
<a href="#Expressions">expression</a>; it is the most recent value
<a href="#Assignment_statements">assigned</a> to the variable.

- 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.

- New "dry_run" metric label (indicating the value of the dryRun query parameter) has been added into the metrics:
  * apiserver_request_total
  * apiserver_request_duration_seconds  

### 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.

  - `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`)

  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.

### 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))

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

* Feature gates now check minimum versions ([#54539](https://github.com/kubernetes/kubernetes/pull/54539), [@jamiehannaford](https://github.com/jamiehannaford))