* Created a new `dryRun` query parameter for mutating endpoints. If the parameter is set, then the query will be rejected, as the feature is not implemented yet. This will allow forward compatibility with future clients; otherwise, future clients talking with older apiservers might end up modifying a resource even if they include the `dryRun` query parameter. ([#63557](https://github.com/kubernetes/kubernetes/pull/63557), [@apelisse](https://github.com/apelisse))

- `kubeadm`: turned on feature gate `MergeCLIArgumentsWithConfig` to merge the config from flag and config file, otherwise, if the flag `--ignore-preflight-errors` is set from the CLI, then the value from config file will be ignored. ([#119946](https://github.com/kubernetes/kubernetes/pull/119946), [@chendave](https://github.com/chendave))

- Reduce default NodeStatusReportFrequency to 5 minutes. With this change, periodic node status updates will be send every 5m if node status doesn't change (otherwise they are still send with 10s).

Some upgrade methods might upgrade etcd from 3.0 to 3.1 automatically when you upgrade from Kubernetes 1.8, unless you specify otherwise. Because [etcd does not support downgrading](https://coreos.com/etcd/docs/latest/upgrades/upgrade_3_1.html), you'll need to either remain on etcd 3.1 or restore from a backup if you want to downgrade back to Kubernetes 1.8.

- Bumped `ProcMountType` feature to on by default beta ([#130798](http...

  New Pods that have a node- or cluster-critical priority are prohibited from accessing swap on Linux,
  even if your cluster and node configuration could otherwise allow this. ([#125277](https://github.com/kubernetes/kubernetes/pull/125277), [@iholder101](https://github.com/iholder101)) [SIG Node and Testing]

JSON API clients should tolerate `null` values for such fields, and treat `null` and `[]` as equivalent in meaning unless specifically documented otherwise for a particular field. ([#44593](https://github.com/kubernetes/kubernetes/pull/44593))

### Other notable changes

- Added support for CEL expressions with escaped names in the structured authentication config. Using `[...]` to access claims or user data was recommended when names contained characters that would otherwise need escaping. CEL optionals with `?` could be used where has was not applicable — for example, `claims[?"kubernetes.io"]` or `user.extra[?"domain.io/foo"]`. ([#131574](https://github.com/kubernetes/kubernetes/pull/131574), [@enj](https://github.com/enj))...

* fluentd-gcp resources can be modified via a ScalingPolicy. ([#59657](https://github.com/kubernetes/kubernetes/pull/59657), [@x13n](https://github.com/x13n))

* Added anti-affinity to kube-dns pods. Otherwise the "no single point of failure" setting doesn't actually work (a single node failure can still take down the entire cluster). ([#57683](https://github.com/kubernetes/kubernetes/pull/57683), [@vainu-arto](https://github.com/vainu-arto))