- Alpha implementation of Kubectl Command Headers: SIG CLI KEP 859 enabled when KUBECTL_COMMAND_HEADERS environment variable set on the client command line.
  - To enable: export KUBECTL_COMMAND_HEADERS=1; kubectl ... ([#98952](https://github.com/kubernetes/kubernetes/pull/98952), [@seans3](https://github.com/seans3)) [SIG API Machinery and CLI]

- Fixed a regression in default 1.27 configurations in kube-apiserver: fixed the AggregatedDiscoveryEndpoint feature (beta in 1.27+) to successfully fetch discovery information from aggregated API servers that do not check `Accept` headers when serving the `/apis` endpoint ([#120360](https://github.com/kubernetes/kubernetes/pull/120360), [@Jefftree](https://github.com/Jefftree)) [SIG API Machinery]

- Kube-proxy handles Terminating EndpointSlices conditions and enables zero downtime deployments for Services with ExternalTrafficPolicy=Local author: @andrewsykim ([#117718](https://github.com/kubernetes/kubernetes/pull/117718), [@aojea](https://github.com/aojea)) [SIG Network, Testing and Windows]

* GCE: Bump GLBC version to [0.9.7](https://github.com/kubernetes/ingress/releases/tag/0.9.7). ([#53625](https://github.com/kubernetes/kubernetes/pull/53625), [@nikhiljindal](https://github.com/nikhiljindal))
* kubeadm 1.8 now properly handles upgrades from to 1.7.x to newer release in 1.7 branch ([#53338](https://github.com/kubernetes/kubernetes/pull/53338), [@kad](https://github.com/kad))

- `--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
  ```

### Other (Cleanup or Flake)

- Kube-apiserver: sets an upper-bound on the lifetime of idle keep-alive connections and time to read the headers of incoming requests ([#103958](https://github.com/kubernetes/kubernetes/pull/103958), [@liggitt](https://github.com/liggitt)) [SIG API Machinery and Node]

## Dependencies

### Added
_Nothing has changed._

- Fixed an issue where kubelet does not set case-insensitive headers for http probes. (#117182, @dddddai) ([#117333](https://github.com/kubernetes/kubernetes/pull/117333), [@dddddai](https://github.com/dddddai)) [SIG API Machinery, Apps and Node]

### Feature

- Scheduler extender `ignorable` option now handles errors for both filter and bind phases. ([#122503](https://github.com/kubernetes/kubernetes/pull/122503), [@sunbinnnnn](https://github.com/sunbinnnnn))

- 'Container `preStop` and `postStart` lifecycle handlers using `httpGet` now
  honor the specified `scheme` and `headers` fields. This enables setting custom
  headers and changing the scheme to `HTTPS`, consistent with container
  startup/readiness/liveness probe capabilities. Lifecycle handlers configured