- Kube-apiserver: multiple comma-separated protocols in a single X-Stream-Protocol-Version header are now recognized, in addition to multiple headers, complying with RFC2616 ([#89857](https://github.com/kubernetes/kubernetes/pull/89857), [@tedyu](https://github.com/tedyu)) [SIG API Machinery]

- '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

- 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

- `TaintBasedEvictions` feature is promoted to beta. ([#69824](https://github.com/kubernetes/kubernetes/pull/69824),...

- Fixed a regression in the kubelet's behavior while creating a container when the `EventedPLEG` feature...

- Kube-apiserver: multiple comma-separated protocols in a single X-Stream-Protocol-Version header are now recognized, in addition to multiple headers, complying with RFC2616 ([#89857](https://github.com/kubernetes/kubernetes/pull/89857), [@tedyu](https://github.com/tedyu)) [SIG API Machinery]

- 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))

- `--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`;...

- 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]