- Kubeadm: fix panic in the command "kubeadm certs check-expiration" when "/etc/kubernetes/pki" exists but cannot be read. ([#124124](https://github.com/kubernetes/kubernetes/pull/124124), [@carlory](https://github.com/carlory)) [SIG Cluster Lifecycle]

//  1. client certificates to authenticate to kube-apiserver (with the "kubernetes.io/kube-apiserver-client-kubelet" signerName).
//  2. serving certificates for TLS endpoints kube-apiserver can connect to securely (with the "kubernetes.io/kubelet-serving" signerName).
//
// This API can be used to request client certificates to authenticate to kube-apiserver
// (with the "kubernetes.io/kube-apiserver-client" signerName),

  // If empty, it will be defaulted:
  //  1. If it's a kubelet client certificate, it is assigned
  //     "kubernetes.io/kube-apiserver-client-kubelet".
  //  2. If it's a kubelet serving certificate, it is assigned
  //     "kubernetes.io/kubelet-serving".
  //  3. Otherwise, it is assigned "kubernetes.io/legacy-unknown".
  // Distribution of trust for signers happens out of band.

- Restore --verify-only function in code generation wrappers. ([#123261](https://github.com/kubernetes/kubernetes/pull/123261), [@skitt](https://github.com/skitt)) [SIG API Machinery]

- Restore --verify-only function in code generation wrappers. ([#123261](https://github.com/kubernetes/kubernetes/pull/123261), [@skitt](https://github.com/skitt)) [SIG API Machinery]

## Changes by Kind

### Feature

- Kubernetes is now built with go 1.21.8
  - update distroless-iptables to v0.4.6 ([#123762](https://github.com/kubernetes/kubernetes/pull/123762), [@cpanato](https://github.com/cpanato)) [SIG Release and Testing]

### Bug or Regression

- The `StructuredAuthenticationConfiguration` feature is now beta and enabled. ([#123719](https://github.com/kubernetes/kubernetes/pull/123719), [@enj](https://github.com/enj))
- The `kube_codegen` tool now ignores the vendor folder during code generation.

// ContainerResourceMetricSource indicates how to scale on a resource metric known to
// Kubernetes, as specified in requests and limits, describing each pod in the
// current scale target (e.g. CPU or memory).  The values will be averaged
// together before being compared to the target.  Such metrics are built in to
// Kubernetes, and have special scaling options on top of those available to

// ContainerResourceMetricSource indicates how to scale on a resource metric known to
// Kubernetes, as specified in requests and limits, describing each pod in the
// current scale target (e.g. CPU or memory).  The values will be averaged
// together before being compared to the target.  Such metrics are built in to
// Kubernetes, and have special scaling options on top of those available to

  // nodeID of the node from the driver point of view.
  // This field enables Kubernetes to communicate with storage systems that do
  // not share the same nomenclature for nodes. For example, Kubernetes may
  // refer to a given node as "node1", but the storage system may refer to
  // the same node as "nodeA". When Kubernetes issues a command to the storage
  // system to attach a volume to a specific node, it can use this field to