- Component owner can configure the allowlist of metric label with flag '--allow-metric-labels'. ([#99385](https://github.com/kubernetes/kubernetes/pull/99385), [@YoyinZyc](https://github.com/YoyinZyc)) [SIG API Machinery, CLI, Cloud Provider, Cluster Lifecycle, Instrumentation and Release]

packaging a Major Component, but which is not part of that Major
Component, and (b) serves only to enable use of the work with that
Major Component, or to implement a Standard Interface for which an
implementation is available to the public in source code form.  A
"Major Component", in this context, means a major essential component
(kernel, window system, and so on) of the specific operating system

either no local stack frame or no function calls,
the only requirement is to define a Go prototype for the function
in a Go source file in the same package. The name of the assembly
function must not contain the package name component (for example,
function <code>Syscall</code> in package <code>syscall</code> should
use the name <code>·Syscall</code> instead of the equivalent name
<code>syscall·Syscall</code> in its <code>TEXT</code> directive).

### Cluster Lifecycle

This API provided status of etcd, kube-scheduler, and kube-controller-manager components, but only worked when those components were local to the API server, and when kube-scheduler and kube-controller-manager exposed unsecured health endpoints. Instead of this API, etcd health is included in the kube-apiserver health check and kube-scheduler/kube-controller-manager health checks can be made directly against those components' health endpoints. ([#93570](https://github.com/kubernetes/kubernetes/pull/93570),...

  of objects which do not change frequently. ([#113362](https://github.com/kubernetes/kubernetes/pull/113362), [@sxllwx](https://github.com/sxllwx))
- `component-base/logs` is now stricter about not applying configurations multiple
  times and will return an error when that is attempted. Can be overridden by binaries

- Kubeadm: switched the kube-scheduler static Pod to use the endpoints /livez (for startup and liveness probes) and /readyz (for the readiness probe). Previously /healthz was used for all probes, which is deprecated behavior in the scope of this component. ([#126945](https://github.com/kubernetes/kubernetes/pull/126945), [@liangyuanpeng](https://github.com/liangyuanpeng)) [SIG Cluster Lifecycle]

- kubeadm: all master components are now exclusively relying on the `PriorityClassName` pod spec for annotating them as cluster critical components. Since `scheduler.alpha.kubernetes.io/critical-pod` annotation is no longer supported by Kubernetes 1.14 this annotation is no longer added to master components. ([#73857](https://github.com/kubernetes/kubernetes/pull/73857), [@ereslibre](https://github.com/ereslibre))...

        `tf.data.Options()`.
    *   Support cancellation of long-running `reduce`.
    *   Now we use `dataset` node name as prefix instead of the op name, to
        identify the component correctly in metrics, for pipelines with repeated
        components.
    *   Improve the performance of datasets using `from_tensors()`.
    *   Promoting `unbatch` from experimental to core API.

* Kubelet: Periodically reporting image pulling progress in log ([#26145](https://github.com/kubernetes/kubernetes/pull/26145), [@Random-Liu](https://github.com/Random-Liu))