Lifecycle¶

Every VirtualMachineInstance represents a single virtual machine instance. In general, the management of VirtualMachineInstances is kept similar to how Pods are managed: Every VM that is defined in the cluster is expected to be running, just like Pods. Deleting a VirtualMachineInstance is equivalent to shutting it down, this is also equivalent to how Pods behave.

Launching a virtual machine¶

In order to start a VirtualMachineInstance, you just need to create a VirtualMachineInstance object using kubectl:

$ kubectl create -f vmi.yaml

Listing virtual machines¶

VirtualMachineInstances can be listed by querying for VirtualMachineInstance objects:

$ kubectl get vmis

Retrieving a virtual machine instance definition¶

A single VirtualMachineInstance definition can be retrieved by getting the specific VirtualMachineInstance object:

$ kubectl get vmis testvmi

Stopping a virtual machine instance¶

To stop the VirtualMachineInstance, you just need to delete the corresponding VirtualMachineInstance object using kubectl.

$ kubectl delete -f vmi.yaml
# OR
$ kubectl delete vmis testvmi

Note: Stopping a VirtualMachineInstance implies that it will be deleted from the cluster. You will not be able to start this VirtualMachineInstance object again.

Starting and stopping a virtual machine¶

Virtual machines, in contrast to VirtualMachineInstances, have a running state. Thus on VM you can define if it should be running, or not. VirtualMachineInstances are, if they are defined in the cluster, always running and consuming resources.

virtctl is used in order to start and stop a VirtualMachine:

$ virtctl start my-vm
$ virtctl stop my-vm

Note: You can force stop a VM (which is like pulling the power cord, with all its implications like data inconsistencies or [in the worst case] data loss) by

$ virtctl stop my-vm --grace-period 0 --force

Pausing and unpausing a virtual machine¶

Note: Pausing in this context refers to libvirt's virDomainSuspend command:
"The process is frozen without further access to CPU resources and I/O but the memory used by the domain at the hypervisor level will stay allocated"

To pause a virtual machine, you need the virtctl command line tool. Its pause command works on either VirtualMachine s or VirtualMachinesInstance s:

$ virtctl pause vm testvm
# OR
$ virtctl pause vmi testvm

Paused VMIs have a Paused condition in their status:

$ kubectl get vmi testvm -o=jsonpath='{.status.conditions[?(@.type=="Paused")].message}'
VMI was paused by user

Unpausing works similar to pausing:

$ virtctl unpause vm testvm
# OR
$ virtctl unpause vmi testvm