Server-side apply now considers `.spec.defaultBackend` to be an atomic struct.  This means that any field-owner who sets values in that struct (they are mutually exclusive) owns the whole struct. For almost all users this change has no impact; for controllers that want to change the default backend port from number to name (or vice-versa), this makes it easier. ([#126207](https://github.com/kubernetes/kubernetes/pull/126207), [@thockin](https://github.com/thockin))...

  // If specified, no other probes are executed until this completes successfully.
  // If this probe fails, the Pod will be restarted, just as if the livenessProbe failed.
  // This can be used to provide different probe parameters at the beginning of a Pod's lifecycle,
  // when it might take a long time to load data or warm a cache, than during steady-state operation.
  // This cannot be updated.

,1)-1;break;case"week":a=t(this.year(),this.month(),this.date()-this.weekday()+7)-1;break;case"isoWeek":a=t(this.year(),this.month(),this.date()-(this.isoWeekday()-1)+7)-1;break;case"day":case"date":a=t(this.year(),this.month(),this.date()+1)-1;break;case"hour":a=this._d.valueOf(),a+=36e5-rt(a+(this._isUTC?0:6e4*this.utcOffset()),36e5)-1;break;case"minute":a=this._d.valueOf(),a+=6e4-rt(a,6e4)-1;break;case"second":a=this._d.valueOf(),a+=1e3-rt(a,1e3)-1;break}return this._d.setTime(a),M.updateOffs...

Kubernetes 1.8 caused the API server to accept a request with incorrect case and coerce it to correct case, but this behaviour has been fixed in 1.11 and the API server will once again be enforcing the correct case. It’s worth noting that during this time, the `kubectl` tool continued to enforce case-sensitive keys, so users that strictly manage resources with `kubectl` will be unaffected by this change. ([#65034](https://github.com/kubernetes/kubernetes/pull/65034), [@caesarxuchao](https://github.com/caesarxuchao))...

* Use "k8s.gcr.io" for container images rather than "gcr.io/google_containers".  This is just a redirect, for now, so should not impact anyone materially.   ([#54174](https://github.com/kubernetes/kubernetes/pull/54174), [@thockin](https://github.com/thockin))
    * Documentation and tools should all convert to the new name. Users should take note of this in case they see this new name in the system.

## Urgent Upgrade Notes

### (No, really, you MUST read this before you upgrade)

- A deprecated flag `--pod-max-in-unschedulable-pods-duration` was initially planned to be removed in v1.26, but we had to change this plan. We found [an issue](https://github.com/kubernetes/kubernetes/issues/110175) in which Pods can be stuck in the unschedulable pod pool for 5 min, and using this flag is the only workaround for this issue. 

machines and reports it as part of node metrics to heapster. This API call fails for VMware and VirtualBox virtualization environments. This issue is not present in bare metal Windows deployments, in Hyper-V, or on some of the popular public cloud providers.

*   If you run `kubectl get po` while the API server in unreachable, a misleading error is returned: `the server doesn't have a resource type "po"`. To work around this issue, specify the full resource name in the command instead...

- CoreDNS is only officially supported on Linux at this time.  As such, when kubeadm is used to deploy this component into your kubernetes cluster, it will be restricted (using `nodeSelectors`) to run only on nodes with that operating system. This ensures that in clusters which include Windows nodes, the scheduler will not ever attempt to place CoreDNS pods on these machines, reducing setup latency...

  
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