// Cannot be updated.
  // +optional
  optional Lifecycle lifecycle = 12;

  // Optional: Path at which the file to which the container's termination message
  // will be written is mounted into the container's filesystem.
  // Message written is intended to be brief final status, such as an assertion failure message.
  // Will be truncated by the node if greater than 4096 bytes. The total message length across

 - Log messages in JSON format are written to stderr by default now (same as text format) instead of stdout. Users who expected JSON output on stdout must now capture stderr instead or in addition to stdout. ([#106146](https://github.com/kubernetes/kubernetes/pull/106146), [@pohly](https:...

- The PodDisruptionBudget API has been promoted to policy/v1 with no schema changes. The only functional change is that an empty selector (`{}`) written to a policy/v1 PodDisruptionBudget now selects all pods in the namespace. The behavior of the policy/v1beta1 API remains unchanged. The policy/v1beta1 PodDisruptionBudget API is deprecated and will no longer be served in 1.25+. ([#99290](https://...

	Read(p []byte) (n int, err error)
	Close() error
}

type Writer interface {
	Write(p []byte) (n int, err error)
	Close() error
}

// ReadWriter's methods are Read, Write, and Close.
type ReadWriter interface {
	Reader  // includes methods of Reader in ReadWriter's method set
	Writer  // includes methods of Writer in ReadWriter's method set
}
</pre>

<p>

* RBAC objects are now stored in etcd in v1 format. After completing an upgrade to 1.9, RBAC objects (Roles, RoleBindings, ClusterRoles, ClusterRoleBindings) should be migrated to ensure all persisted objects are written in `v1` format, prior to `v1alpha1` support being removed in a future release. ([#52950](https://github.com/kubernetes/kubernetes/pull/52950), [@liggitt](https://github.com/liggitt))

### Other notable changes

* **Multiple schedulers**
  * Modify your PodSpecs that currently use the `scheduler.alpha.kubernetes.io/name` annotation on Pod, to instead use the `schedulerName` field in the PodSpec.
  * Modify any custom scheduler(s) you have written so that they read the `schedulerName` field on Pod instead of the `scheduler.alpha.kubernetes.io/name` annotation.
  * Note that you can only start using the `schedulerName` field **after** you upgrade to 1.6; it is not recognized in 1.5.

- [`KT-57126`](https://youtrack.jetbrains.com/issue/KT-57126) [KLIB Reproducibility] Manifest is written using os-dependent line separators
- [`KT-60850`](https://youtrack.jetbrains.com/issue/KT-60850) K2: FIR2IR generates incorrect signature for fake overrides for common declaration if it called from a platform module

* Defaults for file audit logging backend in batch mode changed: ([#67223](https://github.com/kubernetes/kubernetes/pull/67223), [@tallclair](https://github.com/tallclair))
    * Logs are written 1 at a time (no batching)
    * Only a single writer process (lock contention)

* Fix serialization of EnforceNodeAllocatable ([#44606](https://github.com/kubernetes/kubernetes/pull/44606), [@ivan4th](https://github.com/ivan4th))
* Add --write-config-to flag to kube-proxy to allow users to write the default configuration settings to a file. ([#45908](https://github.com/kubernetes/kubernetes/pull/45908), [@ncdc](https://github.com/ncdc))

### Dockershim deprecation

Docker as an underlying runtime is being deprecated. Docker-produced images will continue to work in your cluster with all runtimes, as they always have.
The Kubernetes community [has written a blog post about this in detail](https://blog.k8s.io/2020/12/02/dont-panic-kubernetes-and-docker/) with [a dedicated FAQ page for it](https://blog.k8s.io/2020/12/02/dockershim-faq/).

### External credential provider for client-go