* Deprecate auto detecting cloud providers in kubelet. Auto detecting cloud providers go against the initiative for out-of-tree cloud providers as we'll now depend on cAdvisor integrations with cloud providers instead of the core repo. In the near future, `--cloud-provider` for kubelet will either be an empty string or `external`.  ([#51312](https://github.com/kubernetes/kubernetes/pull/51312), [@a...

Some upgrade methods might upgrade etcd from 3.0 to 3.1 automatically when you upgrade from Kubernetes 1.8, unless you specify otherwise. Because [etcd does not support downgrading](https://coreos.com/etcd/docs/latest/upgrades/upgrade_3_1.html), you'll need to either remain on etcd 3.1 or restore from a backup if you want to downgrade back to Kubernetes 1.8.

## Introduction to 1.9.0

* GC is now bound by QPS so if you need more QPS to avoid ratelimiting GC, you'll have to set it explicitly. ([#63657](https://github.com/kubernetes/kubernetes/pull/63657), [@shyamjvs](https://github.com/shyamjvs))

is compatible with Kubernetes 1.4 and higher only if you specify a new replication controller name. You will need to update to kubectl 1.4 or higher to use the rolling update command against a 1.4 cluster if you want to keep the original name, or you'll have to do two rolling updates.

If you do happen to use old version kubectl's rolling update against a 1.4 cluster, it will fail, usually with an error message that will direct you here. If you saw that error, then don't worry, the operation...

  It's definitely not something expected for plugin developers,
  and we're trying to eventually remove preCheck completely to fix this.
  Until then we'll register UpdateNodeTaint event for plugins that have NodeAdded event, but don't have UpdateNodeTaint event.
  It'd result in a bad impact on the requeuing efficiency though, a lot better than some Pods being stuck in the

### Windows

- Kubectl port-forward for Windows containers was added in v1.15. To use it, you’ll need to build a new pause image including WinCAT. ([#75479](https://github.com/kubernetes/kubernetes/pull/75479), [@benmoss](https://github.com/benmoss))

- Promote StatefulSet minReadySeconds to GA. This means `--feature-gates=StatefulSetMinReadySeconds=true` are not needed on kube-apiserver and kube-controller-manager binaries and they'll be removed soon following policy at https://kubernetes.io/docs/reference/using-api/deprecation-policy/#deprecation ([#110896](https://github.com/kubernetes/kubernetes/pull/110896), [@ravisantoshgudimetla](https://github.com/ravisantoshgudimetla)) [SIG...