kube-dns addon optional so that users can deploy their own DNS solution. ([#57113](https://github.com/kubernetes/kubernetes/pull/57113), [@wwwtyro](https://github.com/wwwtyro))

* `kubectl port-forward` now supports specifying a service to port forward to, as in `kubectl port-forward svc/myservice 8443:443`. Additional support has also been added for looking up targetPort for a service, as well as enabling using svc/name to select a pod. ([#59809](https://github.com/kubernetes/kubernetes/pull/59809),...

## Dependencies

### Added

* Use full package path for definition name in OpenAPI spec ([#40124](https://github.com/kubernetes/kubernetes/pull/40124), [@mbohlool](https://github.com/mbohlool))
* Follow redirects for streaming requests (exec/attach/port-forward) in the apiserver by default (alpha -> beta). ([#40039](https://github.com/kubernetes/kubernetes/pull/40039), [@timstclair](https://github.com/timstclair))

### Other (Cleanup or Flake)

### Instrumentation

### API Change

- Fixed a bug where startupProbe stopped working after a container's first restart ([#101093](https://github.com/kubernetes/kubernetes/pull/101093), [@wzshiming](https://github.com/wzshiming)) [SIG Node]
- Fixed port-forward memory leak for long-running and heavily used connections. ([#99839](https://github.com/kubernetes/kubernetes/pull/99839), [@saschagrunert](https://github.com/saschagrunert)) [SIG API Machinery and Node]

- CoreDNS: The following directives or keywords are deprecated and will be removed in v1.15:
  - `upstream` option of `kubernetes` plugin, becoming default behavior in v1.15.
  - `proxy` plugin replaced by `forward` plugin

## Removed and deprecated metrics

### Removed metrics

- `reflector_items_per_list`
- `reflector_items_per_watch`
- `reflector_last_resource_version`

* Update to go 1.12.10 ([#83139](https://github.com/kubernetes/kubernetes/pull/83139), [@cblecker](https://github.com/cblecker))
* Use ipv4 in wincat port forward. ([#83036](https://github.com/kubernetes/kubernetes/pull/83036), [@liyanhui1228](https://github.com/liyanhui1228))

* 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), [@apel...