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...

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...

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...

### kubeadm
* Quite a few flags been renamed or removed.  Those options that are removed as flags can still be accessed via the config file.  Most notably this includes external etcd settings and the option for setting the cloud provider on the API server.  The [kubeadm reference documentation](https://kubernetes.io/docs/admin/kubeadm/) is up to date with the new flags.

### Other Deprecations

or `/etc/sysconfig/kubelet`, depending on the system...

    - [Introducing <code>RootCAConfigMap</code>](#introducing-rootcaconfigmap)
    - [<code>kubectl debug</code> graduates to Beta](#kubectl-debug-graduates-to-beta)
    - [Removing deprecated flags in kubeadm](#removing-deprecated-flags-in-kubeadm)
    - [Pod Hostname as FQDN graduates to Beta](#pod-hostname-as-fqdn-graduates-to-beta)

* 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`:

  - The deprecated `--etcd-quorum-read` flag has been removed. Quorum reads are now always enabled when fetching data from etcd. Remove the `--etcd-quorum-read` flag from kube-apiserver invocations before upgrading.
- kube-controller-manager
  - The deprecated `--insecure-experimental-approve-all-kubelet-csrs-for-group` flag has been removed.
- kubelet

- Kubeadm: only enable the klog flags that are still supported for kubeadm, rather than hiding the unwanted flags. This means that the previously unrecommended hidden flags about klog (including `--alsologtostderr`, `--log-backtrace-at`, `--log-dir`, `--logtostderr`, `--log-file`, `--log-file-max-size`, `--one-output`, `--skip-log-headers`, `--stderrthreshold`...

## Action Required

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