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`; the new `cli.Run` does that for commands. That helper function also covers flag normalization and printing of usage and errors in a consistent way (print usage text first if parsing failed, then...

- The new flag `--chunk-size=SIZE` for `kubectl drain` has been promoted to beta, and enabled by default. This flag  may be used to alter the number of items or disable this feature when `0` is passed. ([#100148](https://github.com/kubernetes/kubernetes/pull/100148), [@KnVerey](https://github.com/KnVerey))

### **Node**

*   The kubelet `--network-plugin-dir` flag is removed. This flag was deprecated in version 1.7, and is replaced with `--cni-bin-dir`. ([#53564](https://github.com/kubernetes/kubernetes/pull/53564),[ @supereagle](https://github.com/supereagle))

* The following deprecated flags were removed from `kube-controller-manager`:

  * `replication-controller-lookup-cache-size`
  * `replicaset-lookup-cache-size`
  * `daemonset-lookup-cache-size`

  Don't use these flags. Using deprecated flags causes the server to print a warning. Using a removed flag causes the server to abort the startup.

* The following deprecated flags were removed from `kubelet`:

yujuhong))

* The Kubelet now explicitly registers all of its command-line flags with an internal flagset, which prevents flags from third party libraries from unintentionally leaking into the Kubelet's command-line API. Many unintentionally leaked flags are now marked deprecated, so that users have a chance to migrate away from them before they are removed. In addition, one previously leaked flag, --cloud-provider-gce-lb-src-cidrs, has been entirely removed from the Kubelet's command-line...

- kube-apiserver

  - the `--basic-auth-file` flag and authentication mode is deprecated and will be removed in a future release. It is not recommended for production environments. ([#81152](https://github.com/kubernetes/kubernetes/pull/81152), [@tedyu](https://github.com/tedyu))

StreamingProxyRedirects feature and `--redirect-container-streaming` flag are deprecated, and will be removed in a future release. The default behavior (proxy streaming requests through the kubelet) will be the only supported option. If you are setting `--redirect-container-streaming=true`, then you must migrate off this configuration. The flag will no longer be able to be enabled starting in v1.20. If you are not setting the flag, no action is necessary. ([#88290](https://github.com/kubernetes/ku...

* The deprecated `--service-account-private-key-file` flag has been removed from the cloud-controller-manager. The flag is still present and supported in the kube-controller-manager. ([#65182](https://github.com/kubernetes/kubernetes/pull/65182), [@liggitt](https://github.com/liggitt))

## Action Required

- etcd2 as a backend is deprecated and support will be removed in Kubernetes 1.13.

    These 2 flags can be used only for dual-stack clusters. For non dual-stack clusters, continue to use  `--node-cidr-mask-size` flag to configure the mask size.

    The default node cidr mask size for IPv6 was 24 which is now changed to 64. ([#79993](https://github.com/kubernetes/kubernetes/pull/79993), [@aramase](https://github.com/aramase))