- Api: validation of a `PodSpec` now rejects invalid `ResourceClaim` and `ResourceClaimTemplate` names. For a pod, the name generated for the `ResourceClaim` when using a template also must be valid. ([#116576](https://github.com/kubernetes/kubernetes/pull/116576), [@pohly](https://github.com/pohly))

### API Change

* Make all e2e tests lookup image to use from a centralized place. In that centralized place, add support for multiple platforms. ([#49457](https://github.com/kubernetes/kubernetes/pull/49457), [@mkumatag](https://github.com/mkumatag))

## Before Upgrading

* If you need to downgrade from 1.10 to 1.9.x, downgrade to v1.9.6 to ensure PV and PVC objects can be deleted properly.

* In-place node upgrades to this release from versions 1.7.14, 1.8.9, and 1.9.4 are not supported if using subpath volumes with PVCs.  Such pods should be drained from the node first.

* Make all e2e tests lookup image to use from a centralized place. In that centralized place, add support for multiple platforms. ([#49457](https://github.com/kubernetes/kubernetes/pull/49457), [@mkumatag](https://github.com/mkumatag))

- Kubeadm: implemented structured output of 'kubeadm token list' in JSON, YAML, Go template and JsonPath formats ([#78764](https://github.com/kubernetes/kubernetes/pull/78764), [@bart0sh](https://github.com/bart0sh))

The `IngressClass` resource is used to describe a type of Ingress within a Kubernetes cluster. Ingresses can specify the class they are associated with by using a new `ingressClassName` field on Ingresses. This new resource and field replace the deprecated `kubernetes.io/ingress.class` annotation.

### SIG CLI introduces kubectl debug

- kube-controller-manager now uses the informer cache instead of active pod gets in HPA controller ([#68241](https://github.com/kubernetes/kubernetes/pull/68241), [@krzysztof-jastrzebski](https://github.com/krzysztof-jastrzebski))

  apiserver_flowcontrol_current_executing_requests ([#119110](https://github.com/kubernetes/kubernetes/pull/119110), [@andrewsykim](https://github.com/andrewsykim)) [SIG API Machinery and Instrumentation]
- Replace `apiserver_storage_db_total_size_in_bytes` with `apiserver_storage_size_bytes` metric ([#118812](https://github.com/kubernetes/kubernetes/pull/118812), [@serathius](https://github.com/serathius)) [SIG API Machinery, Instrumentation and Testing]

* Restored old behavior to the `--template` flag in `get.go`. In old releases, providing a `--template` flag value and no `--output` value implicitly assigned a default value ("go-template") to `--output`, printing using the provided template argument.
([#65377](https://github.com/kubernetes/kubernetes/pull/65377),[@juanvallejo](https://github.com/juanvallejo))