Using the CLI tools | Virtualization

Prerequisites
OKD client commands
Virtctl commands
Creating a container using virtctl guestfs
Libguestfs tools and virtctl guestfs
Additional resources

The two primary CLI tools used for managing resources in the cluster are:

The OKD Virtualization virtctl client
The OKD oc client

Prerequisites

You must install the virtctl client.

OKD client commands

The OKD oc client is a command-line utility for managing OKD resources, including the VirtualMachine (vm) and VirtualMachineInstance (vmi) object types.

You can use the -n <namespace> flag to specify a different project.

Table 1. `oc` commands
Command	Description
`oc login -u <user_name>`	Log in to the OKD cluster as `<user_name>`.
`oc get <object_type>`	Display a list of objects for the specified object type in the current project.
`oc describe <object_type> <resource_name>`	Display details of the specific resource in the current project.
`oc create -f <object_config>`	Create a resource in the current project from a file name or from stdin.
`oc edit <object_type> <resource_name>`	Edit a resource in the current project.
`oc delete <object_type> <resource_name>`	Delete a resource in the current project.

For more comprehensive information on oc client commands, see the OKD CLI tools documentation.

Virtctl commands

The virtctl client is a command-line utility for managing OKD Virtualization resources.

Table 2. `virtctl` general commands
Command	Description
`virtctl version`	View the `virtctl` client and server versions.
`virtctl help`	View a list of `virtctl` commands.
`virtctl <command> -h\|--help`	View a list of options for a specific command.
`virtctl options`	View a list of global command options for any `virtctl` command.

VM and VMI management commands

You can use virtctl to manage virtual machine (VM) or virtual machine instance (VMI) states and to migrate a VM.

Table 3. `virtctl` VM management commands
Command	Description
`virtctl start <vm_name>`	Start a VM.
`virtctl start --paused <vm_name>`	Start a VM in a paused state. This option enables you to interrupt the boot process from the VNC console.
`virtctl stop <vm_name>`	Stop a VM.
`virtctl stop <vm_name> --grace-period 0 --force`	Force stop a VM. This option might cause data inconsistency or data loss.
`virtctl pause vm\|vmi <vm_name>`	Pause a VM or VMI. The machine state is kept in memory.
`virtctl unpause vm\|vmi <vm_name>`	Unpause a VM or VMI.
`virtctl migrate <vm_name>`	Migrate a VM.
`virtctl restart <vm_name>`	Restart a VM.

VM and VMI connection commands

You can use virtctl to connect to the serial console, expose a port, set a proxy connection, specify a port, and open a VNC connection to a VM.

Table 4. `virtctl console`, `expose`, and `vnc` commands
Command	Description
`virtctl console <vmi_name>`	Connect to the serial console of a VMI.
`virtctl expose <vm_name>`	Create a service that forwards a designated port of a VM or VMI and expose the service on the specified port of the node.
`virtctl vnc --kubeconfig=$KUBECONFIG <vmi_name>`	Open a Virtual Network Client (VNC) connection to a VMI. Accessing the graphical console of a VMI through VNC requires a remote viewer on your local machine.
`virtctl vnc --kubeconfig=$KUBECONFIG --proxy-only=true <vmi_name>`	Display the port number and connect manually to a VMI by using any viewer through the VNC connection.
`virtctl vnc --kubeconfig=$KUBECONFIG --port=<port-number> <vmi_name>`	Specify a port number to run the proxy on the specified port, if that port is available. If a port number is not specified, the proxy runs on a random port.

VM volume export commands

You can use virtctl vmexport commands to create, download, or delete a volume exported from a VM, VM snapshot, or persistent volume claim (PVC).

Table 5. `virtctl vmexport` commands
Command	Description
`virtctl vmexport create <vmexport_name> --vm\|snapshot\|pvc=<object_name>`	Create a `VirtualMachineExport` custom resource (CR) to export a volume from a VM, VM snapshot, or PVC. `--vm`: Exports the PVCs of a VM. `--snapshot`: Exports the PVCs contained in a `VirtualMachineSnapshot` CR. `--pvc`: Exports a PVC. Optional: `--ttl=1h` specifies the time to live. The default duration is 2 hours.
`virtctl vmexport delete <vmexport_name>`	Delete a `VirtualMachineExport` CR manually.
`virtctl vmexport download <vmexport_name> --output=<output_file> --volume=<volume_name>`	Download the volume defined in a `VirtualMachineExport` CR. `--output` specifies the file format. Example: `disk.img.gz`. `--volume` specifies the volume to download. This flag is optional if only one volume is available. Optional: `--keep-vme` retains the `VirtualMachineExport` CR after download. The default behavior is to delete the `VirtualMachineExport` CR after download. `--insecure` enables an insecure HTTP connection.
`virtctl vmexport download <vmexport_name> --<vm\|snapshot\|pvc>=<object_name> --output=<output_file> --volume=<volume_name>`	Create a `VirtualMachineExport` CR and then download the volume defined in the CR.

VM memory dump commands

You can use the virtctl memory-dump command to output a virtual machine (VM) memory dump on a PVC. You can specify an existing PVC or use the --create-claim flag to create a new PVC.

Prerequisites

The PVC volume mode must be FileSystem.
The PVC must be large enough to contain the memory dump.

The formula for calculating the PVC size is (VMMemorySize + 100Mi) * FileSystemOverhead, where 100Mi is the memory dump overhead.

You must enable the hot plug feature gate in the HyperConverged custom resource by running the following command:

$ oc patch hco kubevirt-hyperconverged -n openshift-cnv \
  --type json -p '[{"op": "add", "path": "/spec/featureGates", \
  "value": "HotplugVolumes"}]'

Downloading the memory dump

You must use the virtctl vmexport download command to download the memory dump:

$ virtctl vmexport download <vmexport_name> --vm\|pvc=<object_name> \
  --volume=<volume_name> --output=<output_file>

Table 6. `virtctl memory-dump` commands
Command	Description
`virtctl memory-dump get <vm_name> --claim-name=<pvc_name>`	Save the memory dump of a VM on a PVC. The memory dump status is displayed in the `status` section of the `VirtualMachine` resource. Optional: `--create-claim` creates a new PVC with the appropriate size. This flag has the following options: `--storage-class=<storage_class>`: Specify a storage class for the PVC. `--access-mode=<access_mode>`: Specify `ReadWriteOnce` or `ReadWriteMany`.
`virtctl memory-dump get <vm_name>`	Rerun the `virtctl memory-dump` command with the same PVC. This command overwrites the previous memory dump.
`virtctl memory-dump remove <vm_name>`	Remove a memory dump. You must remove a memory dump manually if you want to change the target PVC. This command removes the association between the VM and the PVC, so that the memory dump is not displayed in the `status` section of the `VirtualMachine` resource. The PVC is not affected.

Image upload commands

You can use the virtctl image-upload commands to upload a VM image to a data volume.

Table 7. `virtctl image-upload` commands
Command	Description
`virtctl image-upload dv <datavolume_name> --image-path=</path/to/image> --no-create`	Upload a VM image to a data volume that already exists.
`virtctl image-upload dv <datavolume_name> --size=<datavolume_size> --image-path=</path/to/image>`	Upload a VM image to a new data volume of a specified requested size.

Environment information commands

You can use virtctl to view information about versions, file systems, guest operating systems, and logged-in users.

Table 8. `virtctl` environment information commands
Command	Description
`virtctl fslist <vmi_name>`	View the file systems available on a guest machine.
`virtctl guestosinfo <vmi_name>`	View information about the operating systems on a guest machine.
`virtctl userlist <vmi_name>`	View the logged-in users on a guest machine.

Creating a container using virtctl guestfs

You can use the virtctl guestfs command to deploy an interactive container with libguestfs-tools and a persistent volume claim (PVC) attached to it.

Procedure

To deploy a container with libguestfs-tools, mount the PVC, and attach a shell to it, run the following command:
```
$ virtctl guestfs -n <namespace> <pvc_name> (1)
```
1 The PVC name is a required argument. If you do not include it, an error message appears.

Libguestfs tools and virtctl guestfs

Libguestfs tools help you access and modify virtual machine (VM) disk images. You can use libguestfs tools to view and edit files in a guest, clone and build virtual machines, and format and resize disks.

You can also use the virtctl guestfs command and its sub-commands to modify, inspect, and debug VM disks on a PVC. To see a complete list of possible sub-commands, enter virt- on the command line and press the Tab key. For example:

Command Description

Command	Description
`virt-edit -a /dev/vda /etc/motd`	Edit a file interactively in your terminal.
`virt-customize -a /dev/vda --ssh-inject root:string:<public key example>`	Inject an ssh key into the guest and create a login.
`virt-df -a /dev/vda -h`	See how much disk space is used by a VM.
`virt-customize -a /dev/vda --run-command 'rpm -qa > /rpm-list'`	See the full list of all RPMs installed on a guest by creating an output file containing the full list.
`virt-cat -a /dev/vda /rpm-list`	Display the output file list of all RPMs created using the `virt-customize -a /dev/vda --run-command 'rpm -qa > /rpm-list'` command in your terminal.
`virt-sysprep -a /dev/vda`	Seal a virtual machine disk image to be used as a template.

virt-edit -a /dev/vda /etc/motd

Edit a file interactively in your terminal.

virt-customize -a /dev/vda --ssh-inject root:string:<public key example>

Inject an ssh key into the guest and create a login.

virt-df -a /dev/vda -h

See how much disk space is used by a VM.

virt-customize -a /dev/vda --run-command 'rpm -qa > /rpm-list'

See the full list of all RPMs installed on a guest by creating an output file containing the full list.

virt-cat -a /dev/vda /rpm-list

Display the output file list of all RPMs created using the virt-customize -a /dev/vda --run-command 'rpm -qa > /rpm-list' command in your terminal.

virt-sysprep -a /dev/vda

Seal a virtual machine disk image to be used as a template.

By default, virtctl guestfs creates a session with everything needed to manage a VM disk. However, the command also supports several flag options if you want to customize the behavior:

Flag Option Description

Flag Option	Description
`--h` or `--help`	Provides help for `guestfs`.
`-n <namespace>` option with a `<pvc_name>` argument	To use a PVC from a specific namespace. If you do not use the `-n <namespace>` option, your current project is used. To change projects, use `oc project <namespace>`. If you do not include a `<pvc_name>` argument, an error message appears.
`--image string`	Lists the `libguestfs-tools` container image. You can configure the container to use a custom image by using the `--image` option.
`--kvm`	Indicates that `kvm` is used by the `libguestfs-tools` container. By default, `virtctl guestfs` sets up `kvm` for the interactive container, which greatly speeds up the `libguest-tools` execution because it uses QEMU. If a cluster does not have any `kvm` supporting nodes, you must disable `kvm` by setting the option `--kvm=false`. If not set, the `libguestfs-tools` pod remains pending because it cannot be scheduled on any node.
`--pull-policy string`	Shows the pull policy for the `libguestfs` image. You can also overwrite the image’s pull policy by setting the `pull-policy` option.

--h or --help

Provides help for guestfs.

-n <namespace> option with a <pvc_name> argument

To use a PVC from a specific namespace.

If you do not use the -n <namespace> option, your current project is used. To change projects, use oc project <namespace>.

If you do not include a <pvc_name> argument, an error message appears.

--image string

Lists the libguestfs-tools container image.

You can configure the container to use a custom image by using the --image option.

--kvm

Indicates that kvm is used by the libguestfs-tools container.

By default, virtctl guestfs sets up kvm for the interactive container, which greatly speeds up the libguest-tools execution because it uses QEMU.

If a cluster does not have any kvm supporting nodes, you must disable kvm by setting the option --kvm=false.

If not set, the libguestfs-tools pod remains pending because it cannot be scheduled on any node.

--pull-policy string

Shows the pull policy for the libguestfs image.

You can also overwrite the image’s pull policy by setting the pull-policy option.

The command also checks if a PVC is in use by another pod, in which case an error message appears. However, once the libguestfs-tools process starts, the setup cannot avoid a new pod using the same PVC. You must verify that there are no active virtctl guestfs pods before starting the VM that accesses the same PVC.

The virtctl guestfs command accepts only a single PVC attached to the interactive pod.

Additional resources

Libguestfs: tools for accessing and modifying virtual machine disk images.