Roles appearing as "<none>" for Worker Nodes when running "kubectl get nodes" command on the Supervisor Cluster

Products

• VMware vSphere Kubernetes Service

Issue/Introduction

• The role will appear as <none> for one or multiple worker nodes when running kubectl get nodes command on the Supervisor cluster. 
  
  
  • kubectl get nodes

NAME                           STATUS          ROLES           AGE     VERSION
<Control_Plane1_Hostname>      Ready    control-plane,master   2d1h   v1.26.8+vmware.wcp.1
<Control_Plane2_Hostname>      Ready    control-plane,master   2d1h   v1.26.8+vmware.wcp.1
<Control_Plane3_Hostname>      Ready    control-plane,master   2d1h   v1.26.8+vmware.wcp.1
<Worker_Node1_Hostname>        Ready    <none>                 47h    v1.26.4-sph-79b2bd9
<Worker_Node2_Hostname>        Ready    agent                  47h    v1.26.4-sph-79b2bd9
<Worker_Node3_Hostname>        Ready    <none>                 47h    v1.26.4-sph-79b2bd9
    
    
  • This can happen after a cluster upgrade or a rolling restart of the nodes. 

Environment

VMware vSphere Kubernetes Service

Cause

• It occurs because of one of the Labels missing on the impacted worker node. 
  
  
• This can be verified via describing the node, and the following Label would be missing - 'node-role.kubernetes.io/agent=agent' 
  
  
  • kubectl describe <impacted_worker_node_name> | grep -i 'label' 

Labels:         beta.kubernetes.io/arch=amd64
                beta.kubernetes.io/os=CRX
                kubernetes.io/arch=amd64
                kubernetes.io/hostname=<worker_node_hostname>
                kubernetes.io/os=CRX
                node.kubernetes.io/role=agent
                type=virtual-kubelet


• Whereas, on a healthy node the label would be present 
  
  
  • kubectl describe <healthy_worker_node_name> | grep -i 'label' 

Labels:         beta.kubernetes.io/arch=amd64
                beta.kubernetes.io/os=CRX
                kubernetes.io/arch=amd64
                kubernetes.io/hostname=<worker_node_hostname>
                kubernetes.io/os=CRX
                node-role.kubernetes.io/agent=agent
                node.kubernetes.io/role=agent
                type=virtual-kubelet

Resolution

• Apply the missing label manually on the impacted worker node with the help of the following command: 
  
  
  • kubectl label node <worker_node_hostname> node-role.kubernetes.io/agent=agent


• Upon running kubectl get nodes command, roles should be visible now 
  
  
  • NAME                           STATUS          ROLES           AGE     VERSION
<Control_Plane1_Hostname>      Ready    control-plane,master   2d1h   v1.26.8+vmware.wcp.1
<Control_Plane2_Hostname>      Ready    control-plane,master   2d1h   v1.26.8+vmware.wcp.1
<Control_Plane3_Hostname>      Ready    control-plane,master   2d1h   v1.26.8+vmware.wcp.1
<Worker_Node1_Hostname>        Ready    agent                  47h    v1.26.4-sph-79b2bd9
<Worker_Node2_Hostname>        Ready    agent                  47h    v1.26.4-sph-79b2bd9
<Worker_Node3_Hostname>        Ready    agent                  47h    v1.26.4-sph-79b2bd9

Additional Information

https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/