#### kubectl:

- Kubelet now exposes `/debug/flags/v` to allow dynamically setting glog logging level.  For example, to change glog level to 3, you only have to send a PUT request like `curl -X PUT http://127.0.0.1:8080/debug/flags/v -d "3"`. ([#64601](https://github.com/kubernetes/kubernetes/pull/64601), [@hzxuzhonghu](https://github.com/hzxuzhonghu))

### SIG OpenStack

* Exposed `/debug/flags/v` to allow dynamically set glog logging level.  For example, to change glog level to 3, send a PUT request such as `curl -X PUT http://127.0.0.1:8080/debug/flags/v -d "3"`. ([#63777](https://github.com/kubernetes/kubernetes/pull/63777), [@hzxuzhonghu](https://github.com/hzxuzhonghu))

* Kubernetes server components using `kubeconfig` files no longer default to `http://localhost:8080`.  Administrators must specify a server value in their kubeconfig files. ([#30808](https://github.com/kubernetes/kubernetes/pull/30808), [@smarterclayton](https://github.com/smarterclayton))

- `kubectl` now contains a `kubectl alpha debug` command. This command allows attaching an ephemeral container to a running pod for the purposes of debugging. ([#88004](https://github.com/kubernetes/kubernetes/pull/88004), [@verb](https://github.com/verb)) [SIG CLI]

### Documentation

- Fixed `threadSafeMap` high memory usage caused by indices that have churn of high-cardinality keys. E.g. namespaces ([#88007](https://github.com/kubernetes/kubernetes/pull/88007), [@patrickshan](https://github.com/patrickshan)) [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
  ```
   ([#107796](https://github.com/kubernetes/kubernetes/pull/107796), [@alexanderConstantinescu](https://github.com/alexanderConstantinescu))

    * You might also want to delete the old secret using this command:
    ```$ kubectl delete secret --namespace=federation federation-apiserver-secret```
* Stop eating panics ([#28800](https://github.com/kubernetes/kubernetes/pull/28800), [@lavalamp](https://github.com/lavalamp))

### Other notable changes

* The kubelet API is now secured, only cluster admins are allowed to access it.
* Insecure access to the API Server over `localhost:8080` is now disabled.
* The control plane components now talk securely to each other. The API Server talks securely to the kubelets in the cluster.

- Fixed `threadSafeMap` high memory usage caused by indices that have churn of high-cardinality keys. E.g. namespaces ([#88005](https://github.com/kubernetes/kubernetes/pull/88005), [@patrickshan](https://github.com/patrickshan)) [SIG API Machinery]