openshift-docs/modules/virt-node-placement-rule-examples.adoc

// Module included in the following assemblies:
//
// * virt/post_installation_configuration/virt-node-placement-virt-components.adoc

:_content-type: REFERENCE
[id="virt-node-placement-rule-examples_{context}"]
= Node placement rule examples

You can specify node placement rules for a {VirtProductName} component by editing a `Subscription`, `HyperConverged`, or `HostPathProvisioner` object.

[id="subscription-object-node-placement-rules_{context}"]
== Subscription object node placement rule examples

To specify the nodes where OLM deploys the {VirtProductName} Operators, edit the `Subscription` object during {VirtProductName} installation.

Currently, you cannot configure node placement rules for the `Subscription` object by using the web console.

The `Subscription` object does not support the `affinity` node pplacement rule.

.Example `Subscription` object with `nodeSelector` rule
[source,yaml,subs="attributes+"]
----
apiVersion: operators.coreos.com/v1beta1
kind: Subscription
metadata:
  name: hco-operatorhub
  namespace: {CNVNamespace}
spec:
  source: {CNVSubscriptionSpecSource}
  sourceNamespace: openshift-marketplace
  name: {CNVSubscriptionSpecName}
  startingCSV: kubevirt-hyperconverged-operator.v{HCOVersion}
  channel: "stable"
  config:
    nodeSelector:
      example.io/example-infra-key: example-infra-value <1>
----
<1> OLM deploys the {VirtProductName} Operators on nodes labeled `example.io/example-infra-key = example-infra-value`.

.Example `Subscription` object with `tolerations` rule
[source,yaml,subs="attributes+"]
----
apiVersion: operators.coreos.com/v1beta1
kind: Subscription
metadata:
  name: hco-operatorhub
  namespace: {CNVNamespace}
spec:
  source:  {CNVSubscriptionSpecSource}
  sourceNamespace: openshift-marketplace
  name: {CNVSubscriptionSpecName}
  startingCSV: kubevirt-hyperconverged-operator.v{HCOVersion}
  channel: "stable"
  config:
    tolerations:
    - key: "key"
      operator: "Equal"
      value: "virtualization" <1>
      effect: "NoSchedule"
----
<1> OLM deploys {VirtProductName} Operators on nodes labeled `key = virtualization:NoSchedule` taint. Only pods with the matching tolerations are scheduled on these nodes.

[id="hyperconverged-object-node-placement-rules_{context}"]
== HyperConverged object node placement rule example

To specify the nodes where {VirtProductName} deploys its components, you can edit the `nodePlacement` object in the HyperConverged custom resource (CR) file that you create during {VirtProductName} installation.

.Example `HyperConverged` object with `nodeSelector` rule
[source,yaml,subs="attributes+"]
----
apiVersion: hco.kubevirt.io/v1beta1
kind: HyperConverged
metadata:
  name: kubevirt-hyperconverged
  namespace: {CNVNamespace}
spec:
  infra:
    nodePlacement:
      nodeSelector:
        example.io/example-infra-key: example-infra-value <1>
  workloads:
    nodePlacement:
      nodeSelector:
        example.io/example-workloads-key: example-workloads-value <2>
----
<1> Infrastructure resources are placed on nodes labeled `example.io/example-infra-key = example-infra-value`.
<2> workloads are placed on nodes labeled `example.io/example-workloads-key = example-workloads-value`.

.Example `HyperConverged` object with `affinity` rule
[source,yaml,subs="attributes+"]
----
apiVersion: hco.kubevirt.io/v1beta1
kind: HyperConverged
metadata:
  name: kubevirt-hyperconverged
  namespace: {CNVNamespace}
spec:
  infra:
    nodePlacement:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: example.io/example-infra-key
                operator: In
                values:
                - example-infra-value <1>
  workloads:
    nodePlacement:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: example.io/example-workloads-key <2>
                operator: In
                values:
                - example-workloads-value
          preferredDuringSchedulingIgnoredDuringExecution:
          - weight: 1
            preference:
              matchExpressions:
              - key: example.io/num-cpus
                operator: Gt
                values:
                - 8 <3>
----
<1> Infrastructure resources are placed on nodes labeled `example.io/example-infra-key = example-value`.
<2> workloads are placed on nodes labeled `example.io/example-workloads-key = example-workloads-value`.
<3> Nodes that have more than eight CPUs are preferred for workloads, but if they are not available, pods are still scheduled.

.Example `HyperConverged` object with `tolerations` rule
[source,yaml,subs="attributes+"]
----
apiVersion: hco.kubevirt.io/v1beta1
kind: HyperConverged
metadata:
  name: kubevirt-hyperconverged
  namespace: {CNVNamespace}
spec:
  workloads:
    nodePlacement:
      tolerations: <1>
      - key: "key"
        operator: "Equal"
        value: "virtualization"
        effect: "NoSchedule"
----
<1> Nodes reserved for {VirtProductName} components are labeled with the `key = virtualization:NoSchedule` taint. Only pods with matching tolerations are scheduled on reserved nodes.

[id="hostpathprovisioner-object-node-placement-rules_{context}"]
== HostPathProvisioner object node placement rule example

You can edit the `HostPathProvisioner` object directly or by using the web console.

[WARNING]
====
You must schedule the hostPath provisioner and the {VirtProductName} components on the same nodes. Otherwise, virtualization pods that use the hostPath provisioner cannot run. You cannot run virtual machines.
====

The `HostPathProvisioner` object supports the `nodeSelector`, `affinity`, and `tolerations` node placement rules.

.Example `HostPathProvisioner` object with `nodeSelector` rule
[source,yaml]
----
apiVersion: hostpathprovisioner.kubevirt.io/v1beta1
kind: HostPathProvisioner
metadata:
  name: hostpath-provisioner
spec:
  imagePullPolicy: IfNotPresent
  pathConfig:
    path: "</path/to/backing/directory>"
    useNamingPrefix: false
  workload:
    nodeSelector:
      example.io/example-workloads-key: example-workloads-value <1>
----
<1> Workloads are placed on nodes labeled `example.io/example-workloads-key = example-workloads-value`.