* Azure: Container permissions for provisioned volumes have changed to private. If you have existing Azure volumes that were created by Kubernetes v1.6.0-v1.6.5, you should change the permissions on them manually. ([#47605](https://github.com/kubernetes/kubernetes/pull/47605), [@brendandburns](https://github.com/brendandburns))

* The shortcuts that were moved server-side in at least 1.9 have been removed from being hardcoded in kubectl. This means that the client-based restmappers have been moved to client-go, where everyone who needs them can have access. ([#63507](https://github.com/kubernetes/kubernetes/pull/63507), [@deads2k](https://github.com/deads2k))

### API-machinery

- Pod template `schedulingGates` are now mutable for Jobs that are suspended and have never been started ([#115940](https://github.com/kubernetes/kubernetes/pull/115940), [@ahg-g](https://github.com/ahg-g)) [SIG Apps]

- Fixed `threadSafeMap` high memory usage caused by indices that have churn of high-cardinality keys. E.g. namespaces ([#88005](https://github.com/kubernetes/kubernetes/pull/88005), [@patrickshan](https://github.com/patrickshan)) [SIG API Machinery]

### Other notable changes

* hyperkube: add cloud-controller-manager ([#54197](https://github.com/kubernetes/kubernetes/pull/54197), [@colemickens](https://github.com/colemickens))

  - [Known Issues](#known-issues)
    - [Summary API in kubelet doesn't have accelerator metrics](#summary-api-in-kubelet-doesnt-have-accelerator-metrics)
  - [Urgent Upgrade Notes](#urgent-upgrade-notes)
    - [(No, really, you MUST read this before you upgrade)](#no-really-you-must-read-this-before-you-upgrade)

* The metrics APIs, `custom-metrics.metrics.k8s.io` and `metrics`, were moved from `v1alpha1` to `v1beta1`, and renamed to `custom.metrics.k8s.io` and `metrics.k8s.io`, respectively. If you have deployed a custom metrics adapter, ensure that it supports the new API version. If you have deployed Heapster in aggregated API server mode, upgrade Heapster to support the latest API version.

- Kubelet metrics have been changed to buckets. 
  For example the exec/{podNamespace}/{podID}/{containerName} is now just exec. ([#87913](https://github.com/kubernetes/kubernetes/pull/87913), [@cheftako](https://github.com/cheftako)) [SIG Node]

accidental enablement of the new alpha `optionalOldSelf` API field in CustomResourceDefinition validation rules, which should only be allowed to be set when the CRDValidationRatcheting feature gate is enabled. Existing CustomResourceDefinition objects which have the field set will retain it on update, but new CustomResourceDefinition objects will not be permitted to set the field while the CRDValidationRatcheting feature gate is disabled. ([#122343](https://github.com/kubernetes/kubernetes/pull/122343), [...