The identifier <code>f</code> is called the (field or method) <i>selector</i>;
it must not be the <a href="#Blank_identifier">blank identifier</a>.
The type of the selector expression is the type of <code>f</code>.
If <code>x</code> is a package name, see the section on
<a href="#Qualified_identifiers">qualified identifiers</a>.
</p>

<p>
A selector <code>f</code> may denote a field or method <code>f</code> of

### API Change

  don't match the node affinity/selector. This may lead to unschedulable pods if you previously had pods
  matching the spreading selector on those excluded nodes (not matching the node affinity/selector),
  especially when the `topologyKey` is not node-level. Revisit the node affinity and/or pod selector in the

### API Change

### API Change

  - kube-proxy addon starts to use the label `node.kubernetes.io/kube-proxy-ds-ready` instead of `beta.kubernetes.io/kube-proxy-ds-ready` as its node selector.
  - metadata-proxy addon starts to use the label `cloud.google.com/metadata-proxy-ready` instead of `beta.kubernetes.io/metadata-proxy-ready` as its node selector.

#### Storage

 - 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.

 - Selector mutation is disabled for all kinds in the

  - `create service externalname` ([#34789](https://github.com/kubernetes/kubernetes/pull/34789), [@adohe](https://github.com/adohe))
- `set selector` - update selector labels ([#38966](https://github.com/kubernetes/kubernetes/pull/38966), [@kargakis](https://github.com/kargakis))

is evaluated the oldObject and newObject that would be sent to the webhook, and is considered to match if either object matches the selector. A null object (oldObject in the case of create, or newObject in the case of delete) or an object that cannot have labels (like a DeploymentRollback or a PodProxyOptions object) is not considered to match. Use the object selector only if the webhook is opt-in, because end users may skip the admission webhook by setting the labels. ([#78505](https://github.co...

- Services implemented a field selector for the ClusterIP and Type fields.