Control which nodes run workspaces

Control which nodes run OpenShift Dev Spaces workspace Pods by setting nodeSelector and tolerations for compliance, hardware affinity, or zone isolation.

Before you begin

You have an active oc session with administrative permissions to the OpenShift cluster. See This page is not included, but the link has been rewritten to point to the nearest parent document.Getting started with the CLI.
The target nodes are labeled or tainted according to the scheduling rules you want to apply.

Procedure

Set nodeSelector in the CheCluster Custom Resource to schedule workspace Pods on specific nodes:
```
spec:
  devEnvironments:
    nodeSelector:
      <key>: <value>
```
This section must contain a set of key=value pairs for each node label to form the nodeSelector rule.
Set tolerations in the CheCluster Custom Resource to allow workspace Pods to be scheduled on tainted nodes. Tolerations work in the opposite way to nodeSelector. Instead of specifying which nodes the Pod is scheduled on, you specify which nodes the Pod cannot be scheduled on.
```
spec:
  devEnvironments:
    tolerations:
      - effect: NoSchedule
        key: <key>
        value: <value>
        operator: Equal
```
Important:

nodeSelector must be configured during OpenShift Dev Spaces installation. This prevents existing workspaces from failing to run due to volumes affinity conflict caused by existing workspace PVC and Pod being scheduled in different zones.

On large, multizone clusters, Pods and PVCs can be scheduled in different zones. To avoid this, create an additional StorageClass object (pay attention to the allowedTopologies field) to coordinate the PVC creation process.

Pass the name of this newly created StorageClass to OpenShift Dev Spaces through the CheCluster Custom Resource.

Results

Verify the nodeSelector or tolerations configuration in the CheCluster Custom Resource:
```
oc get checluster devspaces -n openshift-devspaces -o jsonpath='{.spec.devEnvironments.nodeSelector}'
```