Taints effects: NoSchedule, PreferNoSchedule, NoExecute - what are they?

In Kubernetes, taints are used to restrict the placement of pods on nodes. There are three main effects of taints:

• NoSchedule: A pod with a corresponding toleration will not be scheduled on a node with this taint. That is, if a pod does not have a toleration for a taint with the NoSchedule effect, the scheduler will not place it on that node.

• PreferNoSchedule: This is a soft rule. The scheduler will try not to place pods without toleration on a node with such a taint, but it may do so if necessary.

• NoExecute: Pods without toleration will be immediately removed from the node if the taint is added, and they will not be scheduled on that node.

Example of usage:

kubectl taint nodes node1 key=value:NoSchedule

This will prevent unsupported pods from running on node1.