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Chapter 8. Using the CLI tools

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

  • The OpenShift Virtualization 
    virtctl
    client
  • The OpenShift Container Platform 
    oc
    client

8.1. Prerequisites
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8.2. OpenShift Container Platform client commands
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The OpenShift Container Platform 

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

Note

You can use the 

-n <namespace>
flag to specify a different project.

Expand
Table 8.1. oc commands
CommandDescription

oc login -u <user_name>

Log in to the OpenShift Container Platform 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 OpenShift Container Platform CLI tools documentation.

8.3. Virtctl client commands
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The 

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

To view a list of 

virtctl
commands, run the following command: 

$ virtctl help

To view a list of options that you can use with a specific command, run it with the 

-h
or 
--help
flag. For example: 

$ virtctl image-upload -h

To view a list of global command options that you can use with any 

virtctl
command, run the following command: 

$ virtctl options

The following table contains the 

virtctl
commands used throughout the OpenShift Virtualization documentation.

Expand
Table 8.2. virtctl client commands
CommandDescription

virtctl start <vm_name>

Start a virtual machine. 

virtctl start --paused <vm_name>

Start a virtual machine in a paused state. This option enables you to interrupt the boot process from the VNC console. 

virtctl stop <vm_name>

Stop a virtual machine. 

virtctl stop <vm_name> --grace-period 0 --force

Force stop a virtual machine. This option might cause data inconsistency or data loss. 

virtctl pause vm|vmi <object_name>

Pause a virtual machine or virtual machine instance. The machine state is kept in memory. 

virtctl unpause vm|vmi <object_name>

Unpause a virtual machine or virtual machine instance. 

virtctl migrate <vm_name>

Migrate a virtual machine. 

virtctl restart <vm_name>

Restart a virtual machine. 

virtctl expose <vm_name>

Create a service that forwards a designated port of a virtual machine or virtual machine instance and expose the service on the specified port of the node. 

virtctl console <vmi_name>

Connect to a serial console of a virtual machine instance. 

virtctl vnc --kubeconfig=$KUBECONFIG <vmi_name>

Open a VNC (Virtual Network Client) connection to a virtual machine instance. Access the graphical console of a virtual machine instance through a VNC which 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 the virtual machine instance 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. 

virtctl image-upload dv <datavolume_name> --image-path=</path/to/image> --no-create

Upload a virtual machine image to a data volume that already exists. 

virtctl image-upload dv <datavolume_name> --size=<datavolume_size> --image-path=</path/to/image>

Upload a virtual machine image to a new data volume. 

virtctl version

Display the client and server version information. 

virtctl fslist <vmi_name>

Return a full list of file systems available on the guest machine. 

virtctl guestosinfo <vmi_name>

Return guest agent information about the operating system. 

virtctl userlist <vmi_name>

Return a full list of logged-in users on the guest machine.

8.4. Creating a container using virtctl guestfs
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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.

8.5. Libguestfs tools and virtctl guestfs
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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:

Expand
CommandDescription

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:

Expand
Flag OptionDescription

--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.

Note

The 

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

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