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),...

### Instrumentation

### Other (Cleanup or Flake)

- `kubeadm`: now respects user provided `kubeconfig` during discovery process ([#113998](https://github.com/kubernetes/kubernetes/pull/113998), [@SataQiu](https://github.com/SataQiu))
- `kubectl port-forward` now exits with exit code 1 when remote connection is
  lost ([#114460](https://github.com/kubernetes/kubernetes/pull/114460), [@brianpursley](https://github.com/brianpursley))

- kubeadm now automatically sets the `--pod-infra-container-image` flag when starting the kubelet.

### SIG IBM Cloud

* 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...

- 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]

* Pods that are marked for deletion and have exceeded their grace period, but are not yet deleted, no longer count toward the resource quota.([#46542](https://github.com/kubernetes/kubernetes/pull/46542))


#### Dynamic Admission Control

- `KMSv1` is deprecated and will only receive security updates going forward. Use `KMSv2` instead. In a future release, Set `--feature-gates=KMSv1=true` to use the deprecated KMSv1 feature. ([#119007](https://github.com/kubernetes/kubernetes/pull/119007), [@aramase](https://github.com/aramase))

### SIG-windows

SIG Windows focused on stability and reliability of our existing feature set. We primarily fixed bugs as we march towards a near future stable release.

## Action Required

- etcd2 as a backend is deprecated and support will be removed in Kubernetes 1.13.