Appendix C. Applying labels and taints to Red Hat OpenShift node

Get the name of one of the nodes you want to label running

oc get nodes

$ oc get nodes

Apply the aap_node_type=control label to the node

oc label node <node-name> aap_node_type=control

$ oc label node <node-name> aap_node_type=control

Verify the creation of the label as follows:

oc get nodes --show-labels | grep <node-name>

$ oc get nodes --show-labels | grep <node-name>

With the label created, the next step is to add a NoSchedule taint to the worker node we have already created a label for.

The following command adds a NoSchedule taint to our node:

oc adm taint nodes <node-name> dedicated=AutomationController:NoSchedule

oc adm taint nodes <node-name> dedicated=AutomationController:NoSchedule

dedicated: This is the key of the taint that is an arbitrary string supplied that identifies the taint.

AutomationController: This is an arbitrary value given to the taint.

NoSchedule: This is the effect of the taint which specifies no pods that don’t tolerate this taint will be scheduled onto this node.

By applying this taint to our node, we are telling the Kubernetes scheduler to reserve this node for certain types of workloads that tolerate the taint. In this case, we are reserving the node for workloads with the dedicated=AutomationController toleration.

Verify the taint has been applied

oc get nodes \
-o jsonpath='{range.items[*]}{@.metadata.name}{"\t"}{@.spec.taints[*].key}:{@.spec.taints[*].value}{"\n"}{end}' \
| grep AutomationController

$ oc get nodes \
-o jsonpath='{range.items[*]}{@.metadata.name}{"\t"}{@.spec.taints[*].key}:{@.spec.taints[*].value}{"\n"}{end}' \
| grep AutomationController