// If true the pod's hostname will be configured as the pod's FQDN, rather than the leaf name (the default).
  // In Linux containers, this means setting the FQDN in the hostname field of the kernel (the nodename field of struct utsname).
  // In Windows containers, this means setting the registry value of hostname for the registry key HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters to FQDN.

rnetes/kubernetes/pull/44744), [@yguo0905](https://github.com/yguo0905))

  * Kubernetes now shares a single PID namespace among all containers in a pod when running with docker >= 1.13.1. This means processes can now signal processes in other containers in a pod, but it also means that the `kubectl exec {pod} kill 1` pattern will cause the Pod to be restarted rather than a single container. ([#45236](https://github.com/kubernetes/kubernetes/pull/45236), [@verb](https://github.com/verb))...

- Changed how the API server handles updates to `.spec.defaultBackend` of Ingress objects.

* **[Pod priority and preemption](https://kubernetes.io/docs/concepts/configuration/pod-priority-preemption/) is now enabled by default.** Note that this means that pods from *any* namespace can now request priority classes that compete with and/or cause preemption of critical system pods that are already running. If that is not desired, disable the PodPriority feature by setting `--feature-gates=PodPriority=false`...

  The possibility of borrowing means that the old metric `apiserver_flowcontrol_request_concurrency_limit` can no longer mean both the configured concurrency limit and the enforced concurrency limit. Henceforth it means the configured concurrency limit.' ([#113485](https://github.com/kubernetes/kubernetes/pull/113485), [@MikeSpreitzer](https://github.com/MikeSpreitzer))

- kubeadm has graduated `kubeadm alpha phase` commands to `kubeadm init phase`. This means that the phases of creating a control-plane node are now tightly integrated as part of the `init` command. Alpha features, not yet ready for GA are still kept under `kubeadm alpha` and we appreciate feedback on them.

For more information, see [#53109](https://github.com/kubernetes/kubernetes/issues/53109).

## Deprecations

This section provides an overview of deprecated API versions, options, flags, and arguments. Deprecated means that we intend to remove the capability from a future release. After removal, the capability will no longer work. The sections are organized by SIGs.

### Apps

  * Caveat: The alpha version no longer supports, and the beta version does not support, the "empty `podAffinityTerm.namespaces` list means all namespaces" behavior. In both alpha and beta it now means "same namespace as the pod specifying this affinity rule."
  * Note that you can only start using the `affinity` field **after** you upgrade to 1.6; it is not recognized in 1.5.

#### Other API changes:
- The beta feature `ServerSideApply` enables tracking and managing changed fields for all new objects, which means there will be `managedFields` in `metadata` with the list of managers and their owned fields.

### **Multicluster**

*   Development of Kubernetes Federation has moved to [github.com/kubernetes/federation](https://github.com/kubernetes/federation). This move out of tree also means that Federation will begin releasing separately from Kubernetes. Impact:
    *   Federation-specific behavior will no longer be included in kubectl
    *   kubefed will no longer be released as part of Kubernetes