### Deployment
* Add ready replicas in Deployments ([#37959](https://github.com/kubernetes/kubernetes/pull/37959), [@kargakis](https://github.com/kargakis))
* Deployments that cannot make progress in rolling out the newest version will now indicate via the API they are blocked

  - [Kubefed](#kubefed)
    - [**Kubernetes API**](#kubernetes-api)
      - [User Provided Extensions](#user-provided-extensions)
    - [**Application Deployment**](#application-deployment)
      - [StatefulSet](#statefulset)
      - [DaemonSet](#daemonset-1)
      - [Deployments](#deployments)
      - [PodDisruptionBudget](#poddisruptionbudget)
    - [**Security**](#security)
      - [Admission Control](#admission-control)

  * You can now set `VolumeMount.Propagation` to `Bidirectional` to enable a particular mount for a container to propagate itself to the host or other containers.

* [alpha] Improve Flex volume deployment

  * Flex volume driver deployment is simplified in the following ways:

    * New driver files can now be automatically discovered and initialized without requiring a kubelet or controller-manager restart.

* Use debian-base instead of busybox as base image for server images ([#70245](ht...

* Deployment will stop adding pod-template-hash labels/selector to ReplicaSets and Pods it adopts. Resources created by Deployments are not affected (will still have pod-template-hash labels/selector).  ([#61615](https://github.com/kubernetes/kubernetes/pull/61615), [@janetkuo](https://github.com/janetkuo))

    *   Support for IPv6-only Kubernetes cluster deployments. **<span style="text-decoration:underline;">Note:</span>** This feature does not provide dual-stack support.
    *   Support for IPv6 Kubernetes control and data planes.
    *   Support for Kubernetes IPv6 cluster deployments using kubeadm.
    *   Support for the iptables kube-proxy backend using ip6tables.

    * action required: Cloud providers other than GCE might want to update their deployments or sample yaml files to reuse the role created via add-on.

### Other notable changes

### Beta

- ReplicaSets and Deployments should always count `.status.availableReplicas` at the correct time without a delay. This results in faster reconciliation of Deployment conditions and faster, unblocked Deployment rollouts. ([#132121](https://github.com/kubernetes/kubernetes/pull/132121), [@atiratree](https://github.com/atiratree)) [SIG Apps]

- When describing deployments, `OldReplicaSets` now always shows all replicasets controlled the deployment, not just those that still have replicas available. ([#113083](https://github.com/kubernetes/kubernetes/pull/113083), [@llorllale](https://github.com/llorllale)) [SIG CLI]