## 0.51.0

* Re-export utils from Starlette:
    * This allows using things like `from fastapi.responses import JSONResponse` instead of `from starlette.responses import JSONResponse`.
    * It's mainly syntax sugar, a convenience for developer experience.

- Upon receiving a LIST request with an expired continue token, the apiserver now returns a continue token together with the 410 "the from parameter is too old" error. If the client does not care about getting a list from a consistent snapshot, the client can use this token to continue listing from the next key, but the returned chunk will be from the latest snapshot. ([#67284](https://github.com/kubernetes/kubernetes/pull/67284), [@caesarxuchao](https://github.com/caesarxuchao))

message ConfigMapEnvSource {
  // The ConfigMap to select from.
  optional LocalObjectReference localObjectReference = 1;

  // Specify whether the ConfigMap must be defined
  // +optional
  optional bool optional = 2;
}

// Selects a key from a ConfigMap.
// +structType=atomic
message ConfigMapKeySelector {
  // The ConfigMap to select from.
  optional LocalObjectReference localObjectReference = 1;

- [`KT-59342`](https://youtrack.jetbrains.com/issue/KT-59342) K2 IDE. FirLazyResolveContractViolationException: `lazyResolveToPhase(TYPES)` cannot be called from a transformer with a phase TYPES

    * cAdvisor metrics can now be scraped from `/metrics/cadvisor` on the kubelet ports.
    * Note that you have to update your scraping jobs to get kubelet-only metrics from `/metrics` and `container_*` metrics from `/metrics/cadvisor`

* etcd2: watching from 0 returns all initial states as ADDED events ([#38079](https://github.com/kubernetes/kubernetes/pull/38079), [@hongchao...

registers all of its command-line flags with an internal flagset, which prevents flags from third party libraries from unintentionally leaking into the Kubelet's command-line API. Many unintentionally leaked flags are now marked deprecated, so that users have a chance to migrate away from them before they are removed. In addition, one previously leaked flag, --cloud-provider-gce-lb-src-cidrs, has been entirely removed from the Kubelet's command-line API, because it is irrelevant to Kubelet operation. The...

</p>


<h3 id="Slice_expressions">Slice expressions</h3>

<p>
Slice expressions construct a substring or slice from a string, array, pointer
to array, or slice. There are two variants: a simple form that specifies a low
and high bound, and a full form that also specifies a bound on the capacity.
</p>

<h4>Simple slice expressions</h4>

<p>
The primary expression
</p>

    * `kubectl create configmap` has a new option `--from-env-file` that populates a configmap from file which follows a key=val format for each line. ([#38882](https://github.com/kubernetes/kubernetes/pull/38882), [@fraenkel](https://github.com/fraenkel))

    * `kubectl create secret` has a new option `--from-env-file` that populates a secret from file which follows a key=val format for each line.

  * Printing/describe

  - *apiserver_cache_list_fetched_objects_total*: Counter of objects read from watch cache in the course of serving a LIST request, broken down by resource_prefix and index_name
  - *apiserver_cache_list_evaluated_objects_total*: Counter of objects tested in the course of serving a LIST request from watch cache, broken down by resource_prefix