CNV-21645: Custom scheduler for VMs

Author: Shikha Jhala

modules/virt-vm-custom-scheduler.adoc

@@ -0,0 +1,75 @@
+// Module included in the following assemblies:
+//
+// * virt/virtual_machines/advanced_vm_management/virt-schedule-vms.adoc      
+
+:_content-type: PROCEDURE                                             
+[id="virt-vm-custom-scheduler_{context}"]                                   
+= Scheduling virtual machines with a custom scheduler
+
+You can use a custom scheduler to schedule a virtual machine (VM) on a node.
+
+.Prerequisites
+* A secondary scheduler is configured for your cluster.
+
+.Procedure
+
+* Add the custom scheduler to the VM configuration by editing the `VirtualMachine` manifest. For example:
++
+[source,yaml]
+----
+apiVersion: kubevirt.io/v1
+kind: VirtualMachine
+metadata:
+  name: vm-fedora
+spec:
+  running: true
+  template:
+    spec:
+      schedulerName: my-scheduler <1>
+      domain:
+        devices:
+          disks:
+            - name: containerdisk
+              disk:
+                bus: virtio
+# ...
+----
+<1> The name of the custom scheduler. If the `schedulerName` value does not match an existing scheduler, the `virt-launcher` pod stays in a `Pending` state until the specified scheduler is found.
+
+
+.Verification
+* Verify that the VM is using the custom scheduler specified in the `VirtualMachine` manifest by checking the `virt-launcher` pod events:
+.. View the list of pods in your cluster by entering the following command:
++
+[source,terminal]
+----
+$ oc get pods
+----
++
+.Example output
+[source,terminal]
+----
+NAME                             READY   STATUS    RESTARTS   AGE
+virt-launcher-vm-fedora-dpc87    2/2     Running   0          24m
+----
+
+.. Run the following command to display the pod events:
++
+[source,terminal]
+----
+$ oc describe pod virt-launcher-vm-fedora-dpc87
+----
++
+The value of the `From` field in the output verifies that the scheduler name matches the custom scheduler specified in the `VirtualMachine` manifest:
++
+.Example output
+[source,terminal]
+----
+[...] 
+Events:
+  Type    Reason     Age   From              Message
+  ----    ------     ----  ----              -------
+  Normal  Scheduled  21m   my-scheduler  Successfully assigned default/virt-launcher-vm-fedora-dpc87 to node01
+[...]
+----
+

virt/virtual_machines/advanced_vm_management/virt-schedule-vms.adoc

@@ -9,6 +9,15 @@ toc::[]
 You can schedule a virtual machine (VM) on a node by ensuring that the VM's CPU model and policy attribute are matched for compatibility with the CPU models and policy attributes supported by the node.
 
 include::modules/virt-policy-attributes.adoc[leveloffset=+1]
+
 include::modules/virt-setting-policy-attributes.adoc[leveloffset=+1]
+
 include::modules/virt-schedule-supported-cpu-model-vms.adoc[leveloffset=+1]
+
 include::modules/virt-schedule-cpu-host-model-vms.adoc[leveloffset=+1]
+
+include::modules/virt-vm-custom-scheduler.adoc[leveloffset=+1]
+
+[role="_additional-resources"]
+.Additional resources
+* xref:../../../nodes/scheduling/secondary_scheduler/nodes-secondary-scheduler-configuring.adoc#nodes-secondary-scheduler-configuring-console_secondary-scheduler-configuring[Deploying a secondary scheduler]