### Auth

 - The RBAC v1alpha1 API group is deprecated in favor of RBAC v1.

 - The API server flag `--experimental-bootstrap-token-auth` is deprecated in favor of `--enable-bootstrap-token-auth`. The `--experimental-bootstrap-token-auth` flag will be removed in version 1.9.

### Autoscaling

 - Consuming metrics directly from Heapster is deprecated in favor of

`kubeadm join` is now blocking on the kubelet performing the TLS Bootstrap properly. Earlier, `kubeadm join` only did the discovery part and exited successfully without checking that the kubelet actually started properly and performed the TLS bootstrap correctly. Now, as kubeadm runs some post-join steps (for example, annotating the Node API object with the CRISocket), `kubeadm join` is now waiting for the kubelet to perform the TLS Bootstrap, and then uses that credential to perform further actions. This...

* Renamed the API server flag `--experimental-bootstrap-token-auth` to `--enable-bootstrap-token-auth`. The old value is accepted with a warning in 1.8 and will be removed in 1.9. ([#51198](https://github.com/kubernetes/kubernetes/pull/51198), [@mattmoyer](https://github.com/mattmoyer))

- client-go releases will no longer have bootstrap (k8s.io/client-go/tools/bootstrap) related code. Any reference to it will break. Please redirect all references to k8s.io/bootstrap instead. ([#67356](https://github.com/kubernetes/kubernetes/pull/67356), [@yliaog](https://github.com/yliaog))

* Set an upper bound (5 minutes) on how long the Kubelet will wait before exiting when the client cert from disk is missing or invalid. This prevents the Kubelet from waiting forever without attempting to bootstrap a new client credentials. ([#59316](https://github.com/kubernetes/kubernetes/pull/59316), [@smarterclayton](https://github.com/smarterclayton))

- Migrated the bootstrap signer controller and the token cleaner controller (within `kube-controller-manager`) to use [contextual logging](https://k8s.io/docs/concepts/cluster-administration/system-logs/#contextual-logging). ([#113464](https://github.com/kubernetes/kube...

- Fixes a panic in kube-controller-manager cleaning up bootstrap tokens ([#82887](https://github.com/kubernetes/kubernetes/pull/82887), [@tedyu](https://github.com/tedyu))

- kubeadm: The kubeadm configuration now supports the definition of more than one control plane instances with their own APIEndpoint. The APIEndpoint for the "bootstrap" control plane instance should be defined using `InitConfiguration.APIEndpoint`, while the APIEndpoints for additional control plane instances should be added using `JoinConfiguration.APIEndpoint`. ([#67832](https://github.com/kubernetes/kubernetes/pull/67832),...

  - [alpha] The `kubeadm` tool makes it much easier to bootstrap Kubernetes. ([docs](http://kubernetes.io/docs/getting-started-guides/kubeadm/)) ([kubernetes/features#11](https://github.com/kubernetes/enhancements/issues/11))

* Node Conformance Test: Add system verification ([#32427](https://github.com/kubernetes/kubernetes/pull/32427), [@Random-Liu](https://github.com/Random-Liu))
* kubelet bootstrap: start hostNetwork pods before we have PodCIDR ([#35526](https://github.com/kubernetes/kubernetes/pull/35526), [@justinsb](https://github.com/justinsb))