Merge pull request #72153 from ereslibre/automated-cherry-pick-of-#72…

…030-upstream-release-1.13

Automated cherry pick of #72030: Fix race condition when joining nodes

cmd/kubeadm/app/cmd/join.go

@@ -586,10 +586,12 @@ func (j *Join) PostInstallControlPlane(initConfiguration *kubeadmapi.InitConfigu
 func waitForTLSBootstrappedClient() error {
 	fmt.Println("[tlsbootstrap] Waiting for the kubelet to perform the TLS Bootstrap...")
 
-	kubeletKubeConfig := filepath.Join(kubeadmconstants.KubernetesDir, kubeadmconstants.KubeletKubeConfigFileName)
 	// Loop on every falsy return. Return with an error if raised. Exit successfully if true is returned.
 	return wait.PollImmediate(kubeadmconstants.APICallRetryInterval, kubeadmconstants.TLSBootstrapTimeout, func() (bool, error) {
-		_, err := os.Stat(kubeletKubeConfig)
+		// Check that we can create a client set out of the kubelet kubeconfig. This ensures not
+		// only that the kubeconfig file exists, but that other files required by it also exist (like
+		// client certificate and key)
+		_, err := kubeconfigutil.ClientSetFromFile(kubeadmconstants.GetKubeletKubeConfigPath())
 		return (err == nil), nil
 	})
 }