### IPv4/IPv6 run

IPv4/IPv6 dual-stack has been reimplemented for 1.20 to support dual-stack Services, based on user and community feedback. If your cluster has dual-stack enabled, you can create Services which can use IPv4, IPv6, or both, and you can change this setting for existing Services. Details are available in updated [IPv4/IPv6 dual-stack docs](https://docs.k8s.io/concepts/services-networking/dual-stack/), which cover the nuanced array of options.

### IPv4/IPv6 Dual-stack Networking graduates to GA

[IPv4/IPv6 dual-stack networking](https://github.com/kubernetes/enhancements/tree/master/keps/sig-network/563-dual-stack) graduates to GA.
Since 1.21, Kubernetes clusters are enabled to support dual-stack networking by default.
In 1.23, the `IPv6DualStack` feature gate is removed.
The use of dual-stack networking is not mandatory.

- [IPv4/IPv6 dual-stack](https://kubernetes.io/docs/concepts/services-networking/dual-stack) enables the allocation of both IPv4 and IPv6 addresses to Pods and Services.

- Updated the API documentation for Service.Spec.IPFamily to warn that its exact
  semantics will probably change before the dual-stack feature goes GA, and users
  should look at ClusterIP or Endpoints, not IPFamily, to figure out if an existing
  Service is IPv4, IPv6, or dual-stack. ([#91527](https://github.com/kubernetes/kubernetes/pull/91527), [@danwinship](https://github.com/danwinship)) [SIG Apps and Network]

- Kubeadm: update `CoreDNS` to 1.8.4. Grant `CoreDNS` permissions to "list" and "watch" `EndpointSlice` objects to accommodate dual-stack support. ([#102466](https://github.com/kubernetes/kubernetes/pull/102466), [@pacoxu](https://github.com/pacoxu))

- Kubectl stack traces now only print at verbose `-v=99` and not `-v=6` ([#108053](https://github.com/kubernetes/kubernetes/pull/108053), [@eddiezane](https://github.com/eddiezane))

- Graduated HorizontalPodAutoscaler support for per-container metrics to stable. ([#123482](https://github.com/kubernetes/kubernetes/pull/123482), [@sanposhiho](https://github.com/sanposhiho))

* no ([#75820](https://github.com/kubernetes/kubernetes/pull/75820), [@YoubingLi](https://github.com/YoubingLi))
* Use stdlib to log stack trace when a panic occurs ([#75853](https://github.com/kubernetes/kubernetes/pull/75853), [@roycaihw](https://github.com/roycaihw))

- The `CloudDualStackNodeIPs` feature is now `beta`, meaning that when using
  an external cloud provider that has been updated to support the feature,
  you can pass comma-separated dual-stack `--node-ips` to `kubelet` and have
  the cloud provider take both IPs into account. ([#120275](https://github.com/kubernetes/kubernetes/pull/120275), [@danwinship](https://github.com/danwinship))

    * future, client-side validation in 1.14 kubectl against a 1.15 cluster will reject
    * unknown fields for CRDs with validation schema defined. 
* Fix kubelet start failure issue on Azure Stack due to InstanceMetadata setting ([#74936](https://github.com/kubernetes/kubernetes/pull/74936), [@rjaini](https://github.com/rjaini))