- kube-apiserver: a new `--requestheader-uid-headers` flag allows configuring request header authentication to obtain the authenticating user's UID from the specified headers. The suggested value for the new option is `X-Remote-Uid`. When specified, the `kube-system/extension-apiserver-authentication` configmap will include the value in its...

- Changed: default "Accept-Encoding" header removed from HTTP probes. See https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#http-probes ([#96127](https://github.com/kubernetes/kubernetes/pull/96127), [@fonsecas72](https://github.com/fonsecas72)) [SIG Network and Node]

### 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._

- The `RemoteRequestHeaderUID` feature moves to beta and is now enabled by default. This makes the kube-apiserver propagate UIDs in the `X-Remote-Uid` header in requests to the aggregated API servers. The header is not honored by default for incoming requests, but that can be enabled by setting the `--requestheader-uid-headers` flag explicitly. ([#130560](https://github.com/kubernetes/kubernetes/pull/130560), [@stlaz](https://github.com/stlaz))...

### 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-apiserver: Avoid unnecessary repeated calls to `admission webhooks` that reject an update or delete request. ([#104182](https:...

- 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))

* add fieldSelector podIP ([#50091](https://github.com/kubernetes/kubernetes/pull/50091), [@dixudx](https://github.com/dixudx))
* Return Audit-Id http response header for trouble shooting ([#49377](https://github.com/kubernetes/kubernetes/pull/49377), [@CaoShuFeng](https://github.com/CaoShuFeng))

request alternate representations of normal Kubernetes objects by passing an `Accept` header like `application/json;as=Table;g=meta.k8s.io;v=v1beta1` or `application/json;as=PartialObjectMetadata;g=meta.k8s.io;v1=v1beta1`.  Older servers will ignore this representation or return an error if it is not available.  Clients may request fallback to the normal object by adding a non-qualified mime-type to their `Accept` header like `application/json` - the server will then respond with either the alternate...