How to use the command 'kubectl taint' (with examples)

The ‘kubectl taint’ command is used to update the taints on one or more nodes in a Kubernetes cluster. Taints are used to repel or attract pods to nodes. By using the ‘kubectl taint’ command, you can add, edit, or remove taints on nodes to control the scheduling of pods.

Use case 1: Apply taint to a node

Code:

kubectl taint nodes node_name label_key=label_value:effect

Motivation: Applying a taint to a node can be beneficial for various use cases. For example, you might want to mark a specific node as unschedulable for certain pods, preventing them from running on that node.

Explanation:

• nodes node_name: Specifies the name of the node on which the taint should be applied.
• label_key=label_value: Defines the key-value pair as the label for the taint.
• effect: Specifies the effect of the taint. It can be one of the following values: NoSchedule, PreferNoSchedule, or NoExecute. ‘NoSchedule’ means that pods without tolerations cannot be scheduled onto the tainted node; ‘PreferNoSchedule’ allows un-tolerated pods, but prefers to avoid scheduling them there, and ‘NoExecute’ means that existing pods running on the node that do not tolerate the taint will be evicted.

Example output:

node/node_name tainted

Use case 2: Remove taint from a node

Code:

kubectl taint nodes node_name label_key:effect-

Motivation: Removing a taint from a node can be useful when you want to allow pods to be scheduled on that node again, regardless of the previous taint.

Explanation:

• nodes node_name: Specifies the name of the node from which the taint should be removed.
• label_key:effect-: Defines the label key and effect that should be removed from the node.

Example output:

taint "label_key" not found

Use case 3: Remove all taints from a node

Code:

kubectl taint nodes node_name label_key-

Motivation: In certain scenarios, you may want to remove all taints from a node. This will allow pods without tolerations to be scheduled on the node.

Explanation:

• nodes node_name: Specifies the name of the node from which all taints should be removed.
• label_key-: Defines the label key that should be removed from the node. Using a hyphen at the end signifies the removal of all taints associated with the label key.

Example output:

taint "label_key" not found

Conclusion:

The ‘kubectl taint’ command is a powerful tool that allows you to manage taints on nodes in a Kubernetes cluster. By applying, removing, or removing all taints from a node, you can control the scheduling behavior of pods and optimize resource allocation within your cluster.