- kube-proxy: a configuration file specified via `--config` is now loaded with strict deserialization, which fails if the config file contains duplicate or unknown fields. This protects against accidentally running with config files that are malformed, mis-indented, or have typos in field names, and getting unexpected behavior. ([#82927](https://github.com/kubernetes/kubernetes/pull/82927), [@ob...

* [fluentd-gcp addon] Update Stackdriver plugin to version 0.6.7 ([#52565](https://github.com/kubernetes/kubernetes/pull/52565), [@crassirostris](https://github.com/crassirostris))
* Remove duplicate proto errors in kubelet. ([#52132](https://github.com/kubernetes/kubernetes/pull/52132), [@adityadani](https://github.com/adityadani))

### SIG Storage

- The AllowedTopologies field inside StorageClass is now validated against set and map semantics. Specifically, there cannot be duplicate TopologySelectorTerms, MatchLabelExpressions keys, or TopologySelectorLabelRequirement Values. ([#66843](https://github.com/kubernetes/kubernetes/pull/66843), [@verult](https://github.com/verult))

- The metric `apiserver_flowcontrol_request_concurrency_limit` has been deprecated and will be removed in a future release.  It is a duplicate of `apiserver_flowcontrol_nominal_limit_seats` (introduced in release 1.26) but has an outdated name and had an outdated HELP string. ([#118959](https://github.com/kubernetes/kubernetes/pull/118959), [@MikeSpreitzer](https://github.com/MikeSpreitzer))...

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.
- Volume Cloning: Duplicate a PersistentVolumeClaim and underlying storage volume using the Kubernetes API via CSI.
- CSIDriver Kubernetes API Object: Simplifies CSI driver discovery and allows CSI Drivers to customize Kubernetes behavior.

  - A `create` or `update` API request with duplicate items in a keyed list no longer wipes out managedFields. Examples include env var entries with the same name, or port entries with the same containerPort in a pod spec.

- Fixed an EndpointSlice Controller hashing bug that could cause EndpointSlices to incorrectly handle Pods with duplicate IP addresses. For example this could happen when a new Pod reused an IP that was also assigned to a Pod in a completed state. ([#115907](https://github.com/kubernetes/kubernetes/pull/115907), [@qinqon](https://github.com/qinqon)) [SIG Apps and Network]...

- EndpointSlice controllers are less likely to create duplicate EndpointSlices. ([#100103](https://github.com/kubernetes/kubernetes/pull/100103), [@robscott](https://github.com/robscott)) [SIG Apps and Network]

* [fluentd-gcp addon] Update Stackdriver plugin to version 0.6.7 ([#52565](https://github.com/kubernetes/kubernetes/pull/52565), [@crassirostris](https://github.com/crassirostris))
* Remove duplicate proto errors in kubelet. ([#52132](https://github.com/kubernetes/kubernetes/pull/52132), [@adityadani](https://github.com/adityadani))

* AWS kube-up: Increase timeout waiting for docker start ([#25405](https://github.com/kubernetes/kubernetes/pull/25405), [@justinsb](https://github.com/justinsb))
* Sort resources in quota errors to avoid duplicate events ([#25161](https://github.com/kubernetes/kubernetes/pull/25161), [@derekwaynecarr](https://github.com/derekwaynecarr))