- Enable SPDY pings to keep connections alive, so that `kubectl exec` and `kubectl portforward` won't be interrupted. ([#97083](https://github.com/kubernetes/kubernetes/pull/97083), [@knight42](https://github.com/knight42)) [SIG API Machinery and CLI]

  
  This is a new major release of kustomize, so there are a few backwards-incompatible changes, most of which are rare use cases, bug fixes with side effects, or things that have been deprecated for multiple releases already:
  

### Network
- The official kube-proxy image (used by kubeadm, among other things) is now compatible with systems running iptables 1.8 in "nft" mode, and will autodetect which mode it should use. ([#82966](https://github.com/kubernetes/kubernetes/pull/82966), [@danwinship](https://github.com/danwinship))

* make using service account credentials from controllers optional ([#35970](https://github.com/kubernetes/kubernetes/pull/35970), [@deads2k](https://github.com/deads2k))
* AWS: strong-typing for k8s vs aws volume ids ([#35883](https://github.com/kubernetes/kubernetes/pull/35883), [@justinsb](https://github.com/justinsb))

- Shell completion has been migrated to Cobra's go solution.  `kubectl` is now smarter about disabling file completion when it does not apply.  Furthermore, completion for the `cp` command does not show all files unless the user has started typing something. ([#96087](https://github.com/kubernetes/kubernetes/pull/96087), [@marckhouzam](https://github.com/marckhouzam)) [SIG CLI]

* Add sync state loop in master's volume reconciler ([#34859](https://github.com/kubernetes/kubernetes/pull/34859), [@jingxu97](https://github.com/jingxu97))
* AWS: strong-typing for k8s vs aws volume ids ([#35883](https://github.com/kubernetes/kubernetes/pull/35883), [@justinsb](https://github.com/justinsb))

- Using `--log-file` is known to be problematic in 1.15. This presents as things being logged multiple times to the same file. The behaviour and details of this issue, as well as some preliminary attempts at fixing it are documented [here](https://github.com/kubernetes/kubernetes/issues/78734#issuecomment-501372131)

### Service