- Regenerate protobuf code to fix CVE-2021-3121 ([#100514](https://github.com/kubernetes/kubernetes/pull/100514), [@joelsmith](https://github.com/joelsmith)) [SIG API Machinery, Auth, CLI, Cloud Provider, Cluster Lifecycle, Instrumentation and Node]

### Feature

### SIG API Machinery

[SIG API Machinery][] is responsible for all aspects of the API server: API registration and discovery, generic API CRUD semantics, admission control, encoding/decoding, conversion, defaulting, persistence layer (etcd), OpenAPI, third-party resources, garbage collection, and client libraries.

- Restore --verify-only function in code generation wrappers. ([#123261](https://github.com/kubernetes/kubernetes/pull/123261), [@skitt](https://github.com/skitt)) [SIG API Machinery]

- Fixes issue where you can't attach more than 15 GCE Persistent Disks to c2, n2, m1, m2 machine types. ([#88602](https://github.com/kubernetes/kubernetes/pull/88602), [@yuga711](https://github.com/yuga711)) [SIG Storage]
- Fixes kubelet crash in client certificate rotation cases ([#88079](https://github.com/kubernetes/kubernetes/pull/88079), [@liggitt](https://github.com/liggitt)) [SIG API Machinery, Auth and Node]

- Supporting Cross RG resources (disks, Azure File and node [Experimental]

Besides the above new features, support for Azure Virtual Machine Scale Sets (VMSS) and Cluster-Autoscaler is now stable and considered GA:

- Azure virtual machine scale sets (VMSS) allow you to create and manage identical load balanced VMs that automatically increase or decrease based on demand or a set schedule.

[#57159](https://github.com/kubernetes/kubernetes/issues/57159).

*   If you are adding Windows Server Virtual Machines as nodes to your Kubernetes environment, there is a compatibility issue with certain virtualization products. Specifically the Windows version of the kubelet.exe calls `GetPhysicallyInstalledSystemMemory` to get the physical memory installed on Windows machines and reports it as part of node metrics to heapster. This API call fails for VMware and VirtualBox virtualization environments....

- Fix kubectl-convert import known versions ([#97754](https://github.com/kubernetes/kubernetes/pull/97754), [@wzshiming](https://github.com/wzshiming)) [SIG CLI and Testing]

### Other (Cleanup or Flake)

- Build etcd image v3.5.12 ([#123069](https://github.com/kubernetes/kubernetes/pull/123069), [@bzsuni](https://github.com/bzsuni)) [SIG API Machinery and Etcd]

## Dependencies

### Added
_Nothing has changed._

    - [Deprecated metrics](#deprecated-metrics)
  - [Notable Features](#notable-features)
  - [API Changes](#api-changes)
  - [Detailed Bug Fixes And Changes](#detailed-bug-fixes-and-changes)
    - [API Machinery](#api-machinery)
    - [Apps](#apps)
    - [Auth](#auth)
    - [AWS](#aws)
    - [Azure](#azure)
    - [CLI](#cli)
    - [Cloud Provider](#cloud-provider)
    - [Cluster Lifecycle](#cluster-lifecycle)
    - [GCP](#gcp)

    - [Node Binaries](#node-binaries-13)
  - [Major Themes](#major-themes)
    - [Node](#node)
    - [Storage](#storage)
    - [Windows](#windows)
    - [OpenStack](#openstack)
    - [API-machinery](#api-machinery)
    - [Auth](#auth)
    - [Azure](#azure)
    - [CLI](#cli)
    - [Network](#network)
  - [Before Upgrading](#before-upgrading)
  - [Known Issues](#known-issues)
  - [Deprecations](#deprecations)