- The disk-cached discovery client is moved from k8s.io/client-go/discovery to k8s.io/client-go/discovery/cached/disk.
The memory-cached discovery client is moved from k8s.io/client-go/discovery/cached to k8s.io/client-go/discovery/cached/memory.
([#72214](https://github.com/kubernetes/kubernetes/pull/72214), [@caesarxuchao](https://github.com/caesarxuchao))

- 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]

  - Aggregated discovery requests can now timeout. Aggregated API servers must complete discovery calls within 5 seconds (other requests can take longer). Use the feature gate `EnableAggregatedDiscoveryTimeout=false` to temporarily revert behavior to the previous 30 second timeout if required (the temporary...

### **Cluster Lifecycle**

*   You must either specify the `--discovery-token-ca-cert-hash` flag to `kubeadm join`, or opt out of the CA pinning feature using `--discovery-token-unsafe-skip-ca-verification`.
*   The default `auto-detect` behavior of the kubelet's `--cloud-provider` flag is removed.

* The kube-apiserver discovery APIs (for example, `/apis`) return information about the API groups being served, and can change dynamically.
During server startup, prior to the server reporting healthy (via `/healthz`), not all API groups may be reported.
Wait for the server to report healthy (via `/healthz`) before depending on the information provided by the discovery APIs.

* Pass-through volume MountOptions to global mount (NodeStageVolume) on the node for CSI ([#80191](https://github.com/kubernetes/kubernetes/pull/80191), [@davidz627](https://github.com/davidz627))
* Fix error in `kubeadm join --discovery-file` when using discovery files with embedded credentials ([#80675](https://github.com/kubernetes/kubernetes/pull/80675), [@fabriziopandini](https://github.com/fabriziopandini))

### API Server Aggregator
* Rename kubernetes-discovery to kube-aggregator ([#39619](https://github.com/kubernetes/kubernetes/pull/39619), [@deads2k](https://github.com/deads2k))
* Fix connection upgrades through kubernetes-discovery ([#38724](https://github.com/kubernetes/kubernetes/pull/38724), [@deads2k](https://github.com/deads2k))

#### Generic API Server

- Fixed cluster autoscaler addon permissions so it can access batch/job. ([#69858](https://github.com/kubernetes/kubernetes/pull/69858), [@losipiuk](https://github.com/losipiuk))

* FC volume plugin: Support WWID for volume identifier ([#48741](https://github.com/kubernetes/kubernetes/pull/48741), [@mtanino](https://github.com/mtanino))
* kubeadm: added enhanced TLS validation for token-based discovery in `kubeadm join` using a new `--discovery-token-ca-cert-hash` flag. ([#49520](https://github.com/kubernetes/kubernetes/pull/49520), [@mattmoyer](https://github.com/mattmoyer))

- Kubeadm: fixed a regression where the JoinConfiguration.discovery.timeout was no longer respected and the value was always hardcoded to "5m" (5 minutes). ([#125481](https://github.com/kubernetes/kubernetes/pull/125481), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]