* Admission control support for versioned configuration files ([#39109](https://github.com/kubern...

- Enabled use of pods with volumes and user namespaces....

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- kube-controller-manager and cloud-controller-manager now hold generated serving certificates in-memory unless a writeable location is specified with --cert-dir ([#69884](https://github.com/kubernetes/kubernetes/pull/69884), [@liggitt](https://github.com/liggitt))

 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
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 * http://www.apache.org/licenses/LICENSE-2.0
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 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

- EndpointSlice controller is now less likely to emit FailedToUpdateEndpointSlices events. ([#100113](https://github.com/kubernetes/kubernetes/pull/100113), [@robscott](https://github.com/robscott)) [SIG Apps and Network]

- InPlacePodVerticalScaling: Memory limits cannot be decreased unless the memory resize restart policy is set to `RestartContainer`. Container resizePolicy is no longer mutable. ([#130183](https://github.com/kubernetes/kubernetes/pull/130183), [@tallclair](https://github.com/tallclair)) [SIG Apps and Node]

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.

 - Kubeadm: during "init" an empty cgroupDriver value in the KubeletConfiguration is now always set to "systemd" unless the user is explicit about it. This requires existing machine setups to configure the container runtime to use the "systemd" driver. Documentation on this topic can be found here: https://kubernetes.io/docs/setup/production-environment/container-runtimes/....

  - Do not use the `PersistentVolumeLabel` admission controller in the configuration files and scripts unless you are dependent on the in-tree GCE and AWS cloud providers.