or move it to a safe location. `kubadm certs renew` will renew the certificate in `super-admin.conf` to one year if the file exists; if it does not exist a "MISSING" note will be printed. `kubeadm upgrade apply` for this release will migrate this particular node to the two file setup. Subsequent kubeadm releases will continue to optionally renew the certificate in `super-admin.conf` if the file exists on disk and if renew on upgrade is not disabled. `kubeadm join --control-plane` will now generate...

### RBAC
* Default ClusterRole and ClusterRoleBinding objects are automatically updated at server start to add missing permissions and subjects (extra permissions and subjects are left in place). To prevent autoupdating a particular role or rolebinding, annotate it with `rbac.authorization.kubernetes.io/autoupdate=false`. ([#41155](https://github.com/kubernetes/kubernetes/pull/41155), [@liggitt](https://github.com/liggitt))

- Transparent kube-proxy restarts when using IPVS are now allowed. ([#75283](https://github.com/kubernetes/kubernetes/pull/75283), [@lbernail](https://github.com/lbernail))
- Packets considered INVALID by conntrack are now dropped. In particular, this fixes
a problem where spurious retransmits in a long-running TCP connection to a service
IP could result in the connection being closed with the error "Connection reset by

- CustomResourceDefinitions introduce `x-kubernetes-map-type` annotation as a CRD API extension. Enables this particular validation for server-side apply. ([#84113](https://github.com/kubernetes/kubernetes/pull/84113), [@enxebre](https://github.com/enxebre))

## Other notable changes
### API Machinery

* IPVS: Disable graceful termination for UDP traffic to solve issues with high number of UDP connections (DNS / syslog in particular) ([#77802](https://github.com/kubernetes/kubernetes/pull/77802), [@lbernail](https://github.com/lbernail))

    *   Clients using older endpoints will be unaffected. This change is only at the REST API level and is independent of the default behavior of particular clients (e.g. this does not affect the default for the kubectl `--cascade` flag).
    *   If you upgrade your client-go libs and use the `AppsV1()` interface, please note that the default garbage collection behavior is changed.

SIG Storage made a lot of progress in the 1.18 release.
In particular, the following storage features are moving to GA in Kubernetes 1.18:
- Raw Block Support: Allow volumes to be surfaced as block devices inside containers instead of just mounted filesystems.

  enabling it you must stop now.' ([#116255](https://github.com/kubernetes/kubernetes/pull/116255), [@danwinship](https://github.com/danwinship))
- Give terminal phase correctly to all pods that will not be restarted. 

  In particular, assign Failed phase to pods which are deleted while pending. Also, assign a terminal 
  phase (Succeeded or Failed, depending on the exit statuses of the pod containers) to pods which
  are deleted while running.
  

* [alpha] Mount namespace propagation

  * The `VolumeMount.Propagation` field for `VolumeMount` in pod containers is now available.

  * 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:

- When the `StrictIPCIDRValidation` feature gate is enabled, Kubernetes will be
  slightly stricter about what values will be accepted as IP addresses and network
  address ranges (“CIDR blocks”).
  
  In particular, octets within IPv4 addresses are not allowed to have any leading
  `0`s, and IPv4-mapped IPv6 values (e.g. `::ffff:192.168.0.1`) are forbidden.
  These sorts of values can potentially cause security problems when different