- `--log-flush-frequency` had no effect in several commands or was missing. Help and warning texts were not always using the right format for a command (`add_dir_header` instead of `add-dir-header`). Fixing this included cleaning up flag handling in component-base/logs: that package no longer adds flags to the global flag sets. Commands which want the klog and `--log-flush-frequency` flags must explicitly call `logs.AddFlags`;...

- Added a path `/header?key=` to `agnhost netexec` allowing one to view what the header value is of the incoming request.

  Ex:
  ```
  $ curl -H "X-Forwarded-For: something" 172.17.0.2:8080/header?key=X-Forwarded-For
  something
  ```

* Fixes CVE-2019-11250: client-go header logging (at verbosity levels >= 7) now masks `Authorization` header contents ([#81330](https://github.com/kubernetes/kubernetes/pull/81330), [@tedyu](https://github.com/tedyu))

### Other (Cleanup or Flake)

- Client-go header logging (at verbosity levels >= 9) now masks `Authorization` header contents ([#95316](https://github.com/kubernetes/kubernetes/pull/95316), [@sfowl](https://github.com/sfowl)) [SIG API Machinery]

## Dependencies

### Added
_Nothing has changed._

- Kube API server accepts `Impersonate-Uid` header to impersonate a user with a specific UID, in the same way that you can currently use `Impersonate-User`, `Impersonate-Group` and `Impersonate-Extra`. ([#99961](https://github.com/kubernetes/kubernetes/pull/99961), [@margocrawf](https://github.com/margocrawf))...

* Add "deploy" abbrev for deployments to kubectl ([#24087](https://github.com/kubernetes/kubernetes/pull/24087), [@Frostman](https://github.com/Frostman))
* --no-header available now for custom-column ([#26696](https://github.com/kubernetes/kubernetes/pull/26696), [@gitfred](https://github.com/gitfred))



# v1.4.0-alpha.1

* Flush conntrack state for removed/changed UDP Services ([#22573](https://github.com/kubernetes/kubernetes/pull/22573), [@freehan](https://github.com/freehan))
* Allow setting the Host header in a httpGet probe ([#24292](https://github.com/kubernetes/kubernetes/pull/24292), [@errm](https://github.com/errm))

* Flush conntrack state for removed/changed UDP Services ([#22573](https://github.com/kubernetes/kubernetes/pull/22573), [@freehan](https://github.com/freehan))
* Allow setting the Host header in a httpGet probe ([#24292](https://github.com/kubernetes/kubernetes/pull/24292), [@errm](https://github.com/errm))

* Bug fixes:

  * Make gcp auth provider not to override the Auth header if it's already exits ([#45575](https://github.com/kubernetes/kubernetes/pull/45575), [@wanghaoran1988](https://github.com/wanghaoran1988))