* sysctl support is now considered beta ([ref](https://github.com/kubernetes/enhancements/issues/34))
* Support for Azure Virtual Machine Scale Sets is now considered beta. ([ref](https://github.com/kubernetes/enhancements/issues/513))
* Azure support for Cluster Autoscaler is now considered beta. ([ref](https://github.com/kubernetes/enhancements/issues/514))

* Kubernetes json deserializer is now case-sensitive to restore compatibility with pre-1.8 servers. ([#65157](https://github.com/kubernetes/kubernetes/pull/65157), [@caesarxuchao](https://github.com/caesarxuchao))
    * If your config files contains fields with wrong case, the config files will be now invalid.

    *  - KUBE_SSH_KEY (for skeleton provider) was previously assumed to be a filename relative to ~/.ssh but can now also be an absolute path

### Other notable changes

*   The "ServiceNodeExclusion" feature gate must now be enabled for the `alpha.service-controller.kubernetes.io/exclude-balancer` annotation on nodes to be honored. ([#54644](https://github.com/kubernetes/kubernetes/pull/54644),[ @brendandburns](https://github.com/brendandburns))

### **Scheduling**

*   Taint key `unreachable` is now in GA.
*   Taint key `notReady` is changed to `not-ready`, and is also now in GA.

  - kubeadm now handles air-gapped environments by using the local client version as a fallback.
  - Some kubeadm commands are now allowed to work in a completely offline mode.
- Certificate handling improvements:
  - Renew certs as part of upgrade.
  - New `kubeadm alpha phase certs renew` command for renewing certificates.
  - Certificates created with kubeadm now have improved uniqueness of Distinguished Name fields.

### Serverside Apply - Beta 2

Server-side Apply was promoted to Beta in 1.16, but is now introducing a second Beta in 1.18. This new version will track and manage changes to fields of all new Kubernetes objects, allowing you to know what changed your resources and when.

### Extending Ingress with and replacing a deprecated annotation with IngressClass

#### Windows
- The Windows containers RunAsUsername feature is now beta.
- Windows worker nodes in a Kubernetes cluster now support Windows Server version 1903 in addition to the existing support for Windows Server 2019
- The RuntimeClass scheduler can now simplify steering Linux or Windows pods to appropriate nodes

## Changelog since v1.21.9

## Changes by Kind

### Feature

- Kubernetes is now built with Golang 1.16.13 ([#107615](https://github.com/kubernetes/kubernetes/pull/107615), [@palnabarun](https://github.com/palnabarun)) [SIG Cloud Provider, Instrumentation, Release and Testing]

- Kubectl [get and describe](https://github.com/kubernetes/enhancements/issues/515) now works with extensions
- Nodes now support [third party monitoring plugins](https://github.com/kubernetes/enhancements/issues/606).
- A new [Scheduling Framework](https://github.com/kubernetes/enhancements/issues/624) for schedule plugins is now Alpha.

 - Scheduler's CycleState now embeds internal read/write locking inside its `Read()` and `Write()` functions. Meanwhile, `Lock()` and `Unlock()` function are removed. Scheduler plugin developers are now required to remove `CycleState#Lock()` and `CycleState#Unlock()`. Just simply use `Read()` and `Write()` as they're natively thread-safe now. ([#101542](https://github.com/kubernetes/kubernetes/pull/101542), [@Huang-Wei](https://github.com/Huang-Wei))...