import java.net.SocketTimeoutException
import java.net.URI
import java.net.URLConnection
import java.net.UnknownHostException
import java.security.KeyStore
import java.security.cert.CertificateException
import java.security.cert.X509Certificate
import java.time.Duration
import java.util.Arrays
import java.util.EnumSet
import java.util.Locale
import java.util.concurrent.TimeUnit

credentials in the certificates directory as `kubelet-client.key` and `kubelet-client.crt`.  Subsequent certificates created by cert rotation were created in a combined PEM file that was atomically rotated as `kubelet-client-DATE.pem` in that directory, which meant clients relying on the `node.kubeconfig` generated by bootstrapping would never use a rotated cert.  The initial bootstrap certificate is now generated into the cert directory as a PEM file and symlinked to `kubelet-client-current.pem` so that...

tes/pull/57902), [@kawych](https://github.com/kawych))

* On cluster provision or upgrade, kubeadm now generates certs and secures all connections to the etcd static-pod with mTLS. This includes the etcd serving cert, the etcd peer cert, and the apiserver etcd client cert. Flags and hostMounts are added to the etcd and apiserver static-pods to load these certs. For connections to etcd, https is now used in favor of http. ([#57415](https://github.com/kubernetes/kubernetes/pull/57415),...

- kubeadm: removed the deprecated sub-phase of 'init kubelet-finilize' called `experimental-cert-rotation`, and use 'enable-client-cert-rotation' instead. ([#126913](https://github.com/kubernetes/kubernetes/pull/126913), [@pacoxu](https://github.com/pacoxu)) [SIG Cluster Lifecycle]

HSPLokhttp3/internal/tls/OkHostnameVerifier;->getSubjectAltNames(Ljava/security/cert/X509Certificate;I)Ljava/util/List;
HSPLokhttp3/internal/tls/OkHostnameVerifier;->isAscii(Ljava/lang/String;)Z
HSPLokhttp3/internal/tls/OkHostnameVerifier;->verify(Ljava/lang/String;Ljava/security/cert/X509Certificate;)Z
HSPLokhttp3/internal/tls/OkHostnameVerifier;->verify(Ljava/lang/String;Ljavax/net/ssl/SSLSession;)Z

- Kubeadm: graduate the "kubeadm alpha certs" command to a parent command "kubeadm certs". The command "kubeadm alpha certs" is deprecated and will be removed in a future release. Please migrate. ([#94938](https://github.com/kubernetes/kubernetes/pull/94938), [@yagonobre](https://github.com/yagonobre)) [SIG Cluster Lifecycle]

  - The flag `--experimental-control-plane` is now deprecated in favor of  `--control-plane`. The flag `--experimental-upload-certs` is now deprecated in favor of `--upload-certs` ([#78452](https://github.com/kubernetes/kubernetes/pull/78452), [@fabriziopandini](https://github.com/fabriziopandini))

- kube-controller-manager currently needs a writable `--cert-dir` (default is `/var/run/kubernetes`) for generating self-signed certificates, when no `--tls-cert-file` or `--tls-private-key-file` are provided.

- Kubeadm: remove the deprecated `--csr-only` and `--csr-dir` flags from `kubeadm init phase certs`. Deprecate the same flags under `kubeadm certs renew`. In both the cases the command `kubeadm certs generate-csr` should be used instead. ([#102108](https://github.com/kubernetes/kubernetes/pull/102108), [@neolit123](https://github.com/neolit123))

 
## Changes by Kind

### Deprecation

- 'kubeadm: marked the sub-phase of ''init kubelet-finilize'' called ''experimental-cert-rotation''
  as deprecated and print a warning if it is used directly; it will be removed in
  a future release. Add a replacement sub-phase ''enable-client-cert-rotation''.' ([#124419](https://github.com/kubernetes/kubernetes/pull/124419), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]