Kubernetes: Make a control plane node a worker

When creating a small Kubernetes cluster with 3 nodes, you might want to make the control plane node also a worker. Remember that on larger clusters it's recommended to not mix the responsabilities os the nodes.

To make a control plane node a worker you should run the following command:

kubectl label node <node-name> node-role.kubernetes.io/worker=worker

If we check the nodes status we cna see the first node now has both control-plane and worker roles.

kubectl get nodes

NAME                           STATUS   ROLES                  AGE   VERSION

eu-central-1.binarycomet.net   Ready    control-plane,worker   78m   v1.32.3

eu-central-2.binarycomet.net   Ready    worker                 53m   v1.32.3

eu-central-3.binarycomet.net   Ready    worker                 25m   v1.32.3

The control plane might be tainted to not accept pods, you can check if that's your case running:

kubectl get nodes eu-central-1.binarycomet.net -o json | jq '.spec.taints'

If it's tainted it will output something similar to this, as you can see the effect NoSchedule tells the cluster this node cannot be the host of pods.

[

  {

    "effect": "NoSchedule",

    "key": "node-role.kubernetes.io/control-plane"

  }

]

To remove that effect run the following command, if your taint key is different adapt it to your cluster:

kubectl taint nodes eu-central-1.binarycomet.net node-role.kubernetes.io/master:NoSchedule-