Basic cluster operations

Basic Kubernetes cluster operations

Check the Kubernets cluster status

Get a list of Kubernetes cluster nodes:

kubectl get nodes

Run the previous command again with a new -o wide option and compare the outputs:

kubectl get nodes -o wide

Check the description of the control plane node cp1:

kubectl describe node cp1

Check the description for the node worker1:

kubectl describe node worker1

Show labels for nodes:

kubectl get nodes --show-labels

Change the role name for data plane nodes:

kubectl label node worker1 node-role.kubernetes.io/worker=
kubectl label node worker2 node-role.kubernetes.io/worker=

or use a simple script to make this change for all workers:
for SRV in worker{1,2,3}; do
kubectl label node $SRV node-role.kubernetes.io/worker=
done

Check nodes labels:

kubectl get nodes
kubectl get nodes --show-labels

Check node taints for a cluster:

kubectl describe nodes | grep Taints

Disable scheduling for worker1:

kubectl taint node worker1 node-role.kubernetes.io/worker=:NoSchedule

Check the node taints once again:

kubectl describe nodes | grep Taints

Check the cluster status:

kubectl get nodes

Remove the node taint from worker1:

kubectl taint node worker1 node-role.kubernetes.io/worker-

Repeat this operation, but this time use the cordon subcommand:

kubectl cordon worker1
kubectl describe nodes | grep Taints
kubectl get nodes

Revert changes:

kubectl uncordon worker1

Annotate the cp1 node:

kubectl annotate node cp1 description="This is Kubernetes control plane node!"

Check the section of annotations:

kubectl describe node cp1

Remove the annotation:

kubectl annotate node cp1 description-