- Describing the CRs will now hide `.metadata.managedFields` ([#114584](https://github.com/kubernetes/kubernetes/pull/114584), [@soltysh](https://github.com/soltysh))
- Discovery document will correctly return the resources for aggregated apiservers that do not implement aggregated disovery ([#115770](https://github.com/kubernetes/kubernetes/pull/115770), [@Jefftree](https://github.com/Jefftree))

- Fix race in alpha aggregated discovery handler
  Yes, discovery document will correctly return the resources for aggregated apiservers that do not implement aggregated disovery ([#115805](https://github.com/kubernetes/kubernetes/pull/115805), [@alexzielenski](https://github.com/alexzielenski)) [SIG API Machinery]

  - 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))

  - 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.

- 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))

### 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

- Volume Cloning: Duplicate a PersistentVolumeClaim and underlying storage volume using the Kubernetes API via CSI.
- CSIDriver Kubernetes API Object: Simplifies CSI driver discovery and allows CSI Drivers to customize Kubernetes behavior.

SIG Storage is also introducing the following new storage features as alpha in Kubernetes 1.18: