- Kubeadm: started using a named port 'probe-port' for all probes in the static pod manifests for kube-apiserver, kube-controller-manager, kube-scheduler and etc. If you have previously patched the port values in probes with kubeadm patches, you must now also patch the named port value in the pod container under 'ports'. ([#132776](https://github.com/kubernetes/kubernetes/pull/132776),...

## Changelog since v1.18.18

## Changes by Kind

### API Change

- We have added a new Priority & Fairness rule that exempts all probes (/readyz, /healthz, /livez) to prevent 
  restarting of "healthy" kube-apiserver instance(s) by kubelet. ([#101114](https://github.com/kubernetes/kubernetes/pull/101114), [@tkashem](https://github.com/tkashem)) [SIG API Machinery]

- Updating kubelet permissions check for Windows nodes to see if process is elevated instead of checking if process owner is in Administrators group ([#111078](https://github.com/kubernetes/kubernetes/pull/111078), [@marosset](https://github.com/marosset)) [SIG Node and Windows]

## Dependencies

### Added

for purposes such as debugging, similar to how `kubectl exec` runs a process in an existing container. Also like `kubectl exec`, no resources are reserved for ephemeral containers and they are not restarted when they exit. Note that container namespace targeting is not yet implemented, so [process namespace sharing](https://kubernetes.io/docs/tasks/configure-pod-container/share-process-namespace/) must be enabled to view process from other containers in the pod. ([#59484](https://github.com/kuber...

  - Health check (liveness & readiness) probes using an HTTPGetAction will no longer follow redirects to different hostnames from the original probe request. Instead, these non-local redirects will be treated as a Success (the documented behavior). In this case an event with reason "ProbeWarning" will be generated, indicating that the redirect...

* azure: update disk lock logic per vm during attach/detach to allow concurrent updates for different nodes. ([#85115](https://github.com/kubernetes/kubernetes/pull/85115), [@aramase](https://github.com/aramase))
* Ensure health probes are created for local traffic policy UDP services on Azure ([#85327](https://github.com/kubernetes/kubernetes/pull/85327), [@nilo19](https://github.com/nilo19))

- Kubeadm: make sure the etcd static pod startup probe uses /health?serializable=false while the liveness probe uses /health?serializable=true&exclude=NOSPACE. The NOSPACE exclusion would allow administrators to address space issues one member at a time. ([#110744](https://github.com/kubernetes/kubernetes/pull/110744), [@neolit1...

* allow group impersonation ([#30803](https://github.com/kubernetes/kubernetes/pull/30803), [@deads2k](https://github.com/deads2k))
* Always return command output for exec probes and kubelet RunInContainer ([#30731](https://github.com/kubernetes/kubernetes/pull/30731), [@ncdc](https://github.com/ncdc))

- Implemented logging and event recording for probe results with an `Unknown` status in the kubelet's prober module. This helped improve the diagnosis and monitoring of cases where container probes returned an `Unknown` result, enhancing the observability and reliability of health checks. ([#125901](https://github.com/kubernetes/kubernetes/pull/125901), [@jralmaraz](htt...

- Pod status updates faster when reacting on probe results. The first readiness probe will be called faster when startup probes succeeded, which will make Pod status as ready faster. ([#98376](https://github.com/kubernetes/kubernetes/pull/98376), [@matthyx](https://github.com/matthyx))