- Adopted a new implementation of watch caches for **list** verbs, using a btree data structure. The new implementation is active by default; you can opt out by disabling the `BtreeWatchCache` feature gate. ([#128415](https://github.com/kubernetes/kubernetes/pull/128415), [@serathius](https://github.com/serathius)) [SIG API Machinery, Auth...

- kubeadm: JoinConfiguration now houses the discovery options in a nested Discovery structure, which in turn has a couple of other nested structures to house more specific options (BootstrapTokenDiscovery and FileDiscovery) ([#67763](https://github.com/kubernetes/kubernetes/pull/67763), [@rosti](https://github.com/rosti))

It is likely that `v1alpha2` will be removed in one of the future Kubernetes releases to be able to develop `v1`.

### Structured logging graduate to Beta

Structured logging reached its Beta milestone. Most log messages from kubelet and kube-scheduler have been converted. Users are encouraged to try out JSON output or parsing of the structured text format and provide feedback on possible solutions for the open issues, such as handling of multi-line strings in log values.

   ([#123384](https://github.com/kubernetes/kubernetes/pull/123384), [@aleksandra-malinowska](https://github.com/aleksandra-malinowska))
- In kubeadm, in the new output API 'output.kubeadm.k8s.io/v1alpha3', the UpgradePlan structure that is used when calling 'kubeadm upgrade plan ... -o yaml|json' was modified to include a list of multiple available upgrades.
   ([#123461](https://github.com/kubernetes/kubernetes/pull/123461), [@carlory](https://github.com/carlory))

### Structured Logging in Kubelet

## **Action Required Before Upgrading**

### Network

- Migrate `volume/csi/csi-client.go` logs to structured logging. ([#99441](https://github.com/kubernetes/kubernetes/pull/99441), [@CKchen0726](https://github.com/CKchen0726))
- Migrate statefulset files to structured logging ([#106109](https://github.com/kubernetes/kubernetes/pull/106109), [@h4ghhh](https://github.com/h4ghhh))

    target.
  
    The comment references an issue with `pure = select(...)` which appears
    to be resolved considering this now builds.
  
  - make kube::util::find-binary not dependent on bazel-out/ structure
  
    Implement an aspect that outputs go_build_mode metadata for go binaries,

 ([#64792](https://github.com/kubernetes/kubernetes/pull/64792), [@luxas](https://github.com/luxas))

- Fixed code-generator client-gen to work with `api/v1`-like package structure. ([#125162](https://github.com/kubernetes/kubernetes/pull/125162), [@sttts](https://github.com/sttts)) [SIG API Machinery and Apps]