During a rolling update, new machines fail to bootstrap. Each new VM reaches the kubeadm phase but does not generate /etc/kubernetes/pki, /var/lib/kubelet/config.yaml , or /etc/kubernetes/admin.conf . The kubelet service does not start, and the machine status remains in a waiting state for nodeRef/Node.

In the node’s bootstrap logs located at /var/log/cloud-init-output.log and /var/log/cloud-init.log , kubeadm terminates during the kubelet-start phase with the following errors:

configmap “kubelet-config” not found

error execution phase kubelet-start: failed to load kubelet configuration: configmap “kubelet-config” not found

MachineSet events show:

Machine has unhealthy node

KubeadmControlPlane (KCP) describe output shows:

waiting for control plane/worker to pass preflight checks to continue reconciliation: Machine does not have a corresponding Node yet (Machine.status.nodeRef not set)

Reviewing /var/log/cloud-init-output.log on the affected node confirms kubeadm fails immediately after attempting to write the kubelet configuration file.

error execution phase preflight: unable to fetch kubeadm-config ConfigMap: failed to get config map:

Network connectivity and control-plane endpoint checks remain functional, isolating the issue to the missing ConfigMap.

This condition prevents new VMs from completing initialization and blocks the rolling update process.

The kubelet-config ConfigMap in the VKS cluster’s kube-system namespace is missing.

During bootstrap, kubeadm retrieves this ConfigMap to obtain the default kubelet configuration parameters required to create /var/lib/kubelet/config.yaml .

If the ConfigMap is absent, kubeadm cannot complete the kubelet-start phase and reports the error “configmap ‘kubelet-config’ not found,” leaving the node unregistered.