### **Instrumentation**

#### **Audit**

*   Adjust batching audit webhook default parameters: increase queue size, batch size, and initial backoff. Add throttling to the batching audit webhook. Default rate limit is 10 QPS. ([#53417](https://github.com/kubernetes/kubernetes/pull/53417),[ @crassirostris](https://github.com/crassirostris))

administrators will be able to place limits by using the new kubelet command line parameter --pod-max-pids. Note that since this is a alpha feature they will need to enable the "SupportPodPidsLimit" feature. By default, we do not set any maximum limit, If an administrator wants to enable this, they should enable SupportPodPidsLimit=true in the --feature-gates= parameter to kubelet and specify the limit using the --pod-max-pids parameter. The limit set is the total count of all processes running in all containers...

- `diskformat` storage class parameter for in-tree vSphere volume plugin is deprecated as of v1.21 release. Please consider updating storageclass and remove `diskformat` parameter. vSphere CSI Driver does not support diskformat storageclass parameter.
  

- Resolves a spurious "Unknown discovery response content-type" error in client-go discovery requests by tolerating extra content-type parameters in API responses ([#117637](https://github.com/kubernetes/kubernetes/pull/117637), [@seans3](https://github.com/seans3)) [SIG API Machinery]

* Fix mounting of UNIX sockets(and other special files) in subpaths ([#61480](https://github.com/kubernetes/kubernetes/pull/61480), [@gnufied](https://github.com/gnufied))
* Fix GCE etcd scripts to pass in all required parameters for the etcd migration utility to correctly perform HA upgrades and downgrades ([#61957](https://github.com/kubernetes/kubernetes/pull/61957), [@jpbetz](https://github.com/jpbetz))

- The deprecated flag `--lock-object-namespace` and `--lock-object-name` have been removed from kube-scheduler. Please use `--leader-elect-resource-namespace` and `--leader-elect-resource-name` or ComponentConfig instead to configure those parameters. ([#119130](https://github.com/kubernetes/kubernetes/pull/119130), [@SataQiu](https://github.com/SataQiu)) [SIG Scheduling]

* Fixed pod cleanup when /var/lib/kubelet is a symlink. ([#68741](https://github.com/kubernetes/kubernetes/pull/68741), [@jsafrane](https://github.com/jsafrane))
* Add "only_cpu_and_memory" GET parameter to /stats/summary http handler in kubelet. If parameter is true then only cpu and memory will be present in response. ([#67829](https://github.com/kubernetes/kubernetes/pull/67829), [@krzysztof-jastrzebski](https://github.com/krzysztof-jastrzebski))

  - HardPodAffinityWeight moved from a top level ComponentConfig parameter to a PluginConfig parameter of InterPodAffinity Plugin in `kubescheduler.config.k8s.io/v1alpha2` ([#88002](https://github.com/kubernetes/kubernetes/pull/88002), [@alculquicondor](https://github.com/alculquicondor)) [SIG Scheduling and Testing]

 - It can be used to provide scratch storage that is different from the root disk, for example persistent memory, or a separate local disk on that node.
 - All StorageClass parameters for volume provisioning are supported.
 - All features supported with PersistentVolumeClaims are supported, such as storage capacity tracking, snapshots and restore, and volume resizing.

- The `IngressClassNamespacedParams` feature gate has graduated to beta and is enabled by default. This means IngressClass resource will now have two new fields - `spec.paramters.namespace` and `spec.parameters.scope`. ([#101711](https://github.com/kubernetes/kubernetes/pull/101711), [@hbagdi](https://github.com/hbagdi))