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Creating virtual machines

Use one of these procedures to create a virtual machine:

  • Quick Start guided tour

  • Quick create from the Catalog

  • Pasting a pre-configured YAML file with the virtual machine wizard

  • Using the CLI

Do not create virtual machines in openshift-* namespaces. Instead, create a new namespace or use an existing namespace without the openshift prefix.

When you create virtual machines from the web console, select a virtual machine template that is configured with a boot source. Virtual machine templates with a boot source are labeled as Available boot source or they display a customized label text. Using templates with an available boot source expedites the process of creating virtual machines.

Templates without a boot source are labeled as Boot source required. You can use these templates if you complete the steps for adding a boot source to the virtual machine.

Due to differences in storage behavior, some virtual machine templates are incompatible with single-node OpenShift. To ensure compatibility, do not set the evictionStrategy field for any templates or virtual machines that use data volumes or storage profiles.

Using a Quick Start to create a virtual machine

The web console provides Quick Starts with instructional guided tours for creating virtual machines. You can access the Quick Starts catalog by selecting the Help menu in the Administrator perspective to view the Quick Starts catalog. When you click on a Quick Start tile and begin the tour, the system guides you through the process.

Tasks in a Quick Start begin with selecting a Red Hat template. Then, you can add a boot source and import the operating system image. Finally, you can save the custom template and use it to create a virtual machine.

Prerequisites

  • Access to the website where you can download the URL link for the operating system image.

Procedure

  1. In the web console, select Quick Starts from the Help menu.

  2. Click on a tile in the Quick Starts catalog. For example: Creating a Red Hat Linux Enterprise Linux virtual machine.

  3. Follow the instructions in the guided tour and complete the tasks for importing an operating system image and creating a virtual machine. The Virtualization → VirtualMachines page displays the virtual machine.

Quick creating a virtual machine

You can quickly create a virtual machine (VM) by using a template with an available boot source.

Procedure

  1. Click Virtualization → Catalog in the side menu.

  2. Click Boot source available to filter templates with boot sources.

    By default, the template list will show only Default Templates. Click All Items when filtering to see all available templates for your chosen filters.

  3. Click a template to view its details.

  4. Click Quick Create VirtualMachine to create a VM from the template.

    The virtual machine Details page is displayed with the provisioning status.

Verification

  1. Click Events to view a stream of events as the VM is provisioned.

  2. Click Console to verify that the VM booted successfully.

Creating a virtual machine from a customized template

Some templates require additional parameters, for example, a PVC with a boot source. You can customize select parameters of a template to create a virtual machine (VM).

Procedure

  1. In the web console, select a template:

    1. Click Virtualization → Catalog in the side menu.

    2. Optional: Filter the templates by project, keyword, operating system, or workload profile.

    3. Click the template that you want to customize.

  2. Click Customize VirtualMachine.

  3. Specify parameters for your VM, including its Name and Disk source. You can optionally specify a data source to clone.

Verification

  1. Click Events to view a stream of events as the VM is provisioned.

  2. Click Console to verify that the VM booted successfully.

Refer to the virtual machine fields section when creating a VM from the web console.

Networking fields

Name Description

Name

Name for the network interface controller.

Model

Indicates the model of the network interface controller. Supported values are e1000e and virtio.

Network

List of available network attachment definitions.

Type

List of available binding methods. Select the binding method suitable for the network interface:

  • Default pod network: masquerade

  • Linux bridge network: bridge

  • SR-IOV network: SR-IOV

MAC Address

MAC address for the network interface controller. If a MAC address is not specified, one is assigned automatically.

Storage fields

Name Selection Description

Source

Blank (creates PVC)

Create an empty disk.

Import via URL (creates PVC)

Import content via URL (HTTP or HTTPS endpoint).

Use an existing PVC

Use a PVC that is already available in the cluster.

Clone existing PVC (creates PVC)

Select an existing PVC available in the cluster and clone it.

Import via Registry (creates PVC)

Import content via container registry.

Container (ephemeral)

Upload content from a container located in a registry accessible from the cluster. The container disk should be used only for read-only filesystems such as CD-ROMs or temporary virtual machines.

Name

Name of the disk. The name can contain lowercase letters (a-z), numbers (0-9), hyphens (-), and periods (.), up to a maximum of 253 characters. The first and last characters must be alphanumeric. The name must not contain uppercase letters, spaces, or special characters.

Size

Size of the disk in GiB.

Type

Type of disk. Example: Disk or CD-ROM

Interface

Type of disk device. Supported interfaces are virtIO, SATA, and SCSI.

Storage Class

The storage class that is used to create the disk.

Advanced storage settings

The following advanced storage settings are optional and available for Blank, Import via URL, and Clone existing PVC disks. Before OKD Virtualization 4.11, if you do not specify these parameters, the system uses the default values from the kubevirt-storage-class-defaults config map. In OKD Virtualization 4.11 and later, the system uses the default values from the storage profile.

Use storage profiles to ensure consistent advanced storage settings when provisioning storage for OKD Virtualization.

To manually specify Volume Mode and Access Mode, you must clear the Apply optimized StorageProfile settings checkbox, which is selected by default.
Name Mode description Parameter Parameter description

Volume Mode

Defines whether the persistent volume uses a formatted file system or raw block state. Default is Filesystem.

Filesystem

Stores the virtual disk on a file system-based volume.

Block

Stores the virtual disk directly on the block volume. Only use Block if the underlying storage supports it.

Access Mode

Access mode of the persistent volume.

ReadWriteOnce (RWO)

Volume can be mounted as read-write by a single node.

ReadWriteMany (RWX)

Volume can be mounted as read-write by many nodes at one time.

This is required for some features, such as live migration of virtual machines between nodes.

ReadOnlyMany (ROX)

Volume can be mounted as read only by many nodes.

Cloud-init fields

Name Description

Authorized SSH Keys

The user’s public key that is copied to ~/.ssh/authorized_keys on the virtual machine.

Custom script

Replaces other options with a field in which you paste a custom cloud-init script.

To configure storage class defaults, use storage profiles. For more information, see Customizing the storage profile.

Pasting in a pre-configured YAML file to create a virtual machine

Create a virtual machine by writing or pasting a YAML configuration file. A valid example virtual machine configuration is provided by default whenever you open the YAML edit screen.

If your YAML configuration is invalid when you click Create, an error message indicates the parameter in which the error occurs. Only one error is shown at a time.

Navigating away from the YAML screen while editing cancels any changes to the configuration you have made.
Procedure

  1. Click Virtualization → VirtualMachines from the side menu.

  2. Click Create and select With YAML.

  3. Write or paste your virtual machine configuration in the editable window.

    1. Alternatively, use the example virtual machine provided by default in the YAML screen.

  4. Optional: Click Download to download the YAML configuration file in its present state.

  5. Click Create to create the virtual machine.

The virtual machine is listed on the VirtualMachines page.

Using the CLI to create a virtual machine

You can create a virtual machine from a virtualMachine manifest.

Procedure

  1. Edit the VirtualMachine manifest for your VM. For example, the following manifest configures a Fedora VM:

    Example manifest for a Fedora VM 
    apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  labels:
    app: <vm_name> (1)
  name: <vm_name>
spec:
  dataVolumeTemplates:
  - apiVersion: cdi.kubevirt.io/v1beta1
    kind: DataVolume
    metadata:
      name: <vm_name>
    spec:
      sourceRef:
        kind: DataSource
        name: rhel9
        namespace: openshift-virtualization-os-images
      storage:
        resources:
          requests:
            storage: 30Gi
  running: false
  template:
    metadata:
      labels:
        kubevirt.io/domain: <vm_name>
    spec:
      domain:
        cpu:
          cores: 1
          sockets: 2
          threads: 1
        devices:
          disks:
          - disk:
              bus: virtio
            name: rootdisk
          - disk:
              bus: virtio
            name: cloudinitdisk
          interfaces:
          - masquerade: {}
            name: default
          rng: {}
        features:
          smm:
            enabled: true
        firmware:
          bootloader:
            efi: {}
        resources:
          requests:
            memory: 8Gi
      evictionStrategy: LiveMigrate
      networks:
      - name: default
        pod: {}
      volumes:
      - dataVolume:
          name: <vm_name>
        name: rootdisk
      - cloudInitNoCloud:
          userData: |-
            #cloud-config
            user: cloud-user
            password: '<password>' (2)
            chpasswd: { expire: False }
        name: cloudinitdisk
    1 Specify the name of the virtual machine.
    2 Specify the password for cloud-user.

  2. Create a virtual machine by using the manifest file:

    $ oc create -f <vm_manifest_file>.yaml

  3. Optional: Start the virtual machine:

    $ virtctl start <vm_name>

Virtual machine storage volume types

Storage volume type Description

ephemeral

A local copy-on-write (COW) image that uses a network volume as a read-only backing store. The backing volume must be a PersistentVolumeClaim. The ephemeral image is created when the virtual machine starts and stores all writes locally. The ephemeral image is discarded when the virtual machine is stopped, restarted, or deleted. The backing volume (PVC) is not mutated in any way.

persistentVolumeClaim

Attaches an available PV to a virtual machine. Attaching a PV allows for the virtual machine data to persist between sessions.

Importing an existing virtual machine disk into a PVC by using CDI and attaching the PVC to a virtual machine instance is the recommended method for importing existing virtual machines into OKD. There are some requirements for the disk to be used within a PVC.

dataVolume

Data volumes build on the persistentVolumeClaim disk type by managing the process of preparing the virtual machine disk via an import, clone, or upload operation. VMs that use this volume type are guaranteed not to start until the volume is ready.

Specify type: dataVolume or type: "". If you specify any other value for type, such as persistentVolumeClaim, a warning is displayed, and the virtual machine does not start.

cloudInitNoCloud

Attaches a disk that contains the referenced cloud-init NoCloud data source, providing user data and metadata to the virtual machine. A cloud-init installation is required inside the virtual machine disk.

containerDisk

References an image, such as a virtual machine disk, that is stored in the container image registry. The image is pulled from the registry and attached to the virtual machine as a disk when the virtual machine is launched.

A containerDisk volume is not limited to a single virtual machine and is useful for creating large numbers of virtual machine clones that do not require persistent storage.

Only RAW and QCOW2 formats are supported disk types for the container image registry. QCOW2 is recommended for reduced image size.

A containerDisk volume is ephemeral. It is discarded when the virtual machine is stopped, restarted, or deleted. A containerDisk volume is useful for read-only file systems such as CD-ROMs or for disposable virtual machines.

emptyDisk

Creates an additional sparse QCOW2 disk that is tied to the life-cycle of the virtual machine interface. The data survives guest-initiated reboots in the virtual machine but is discarded when the virtual machine stops or is restarted from the web console. The empty disk is used to store application dependencies and data that otherwise exceeds the limited temporary file system of an ephemeral disk.

The disk capacity size must also be provided.

About RunStrategies for virtual machines

A RunStrategy for virtual machines determines a virtual machine instance’s (VMI) behavior, depending on a series of conditions. The spec.runStrategy setting exists in the virtual machine configuration process as an alternative to the spec.running setting. The spec.runStrategy setting allows greater flexibility for how VMIs are created and managed, in contrast to the spec.running setting with only true or false responses. However, the two settings are mutually exclusive. Only either spec.running or spec.runStrategy can be used. An error occurs if both are used.

There are four defined RunStrategies.

Always

A VMI is always present when a virtual machine is created. A new VMI is created if the original stops for any reason, which is the same behavior as spec.running: true.

RerunOnFailure

A VMI is re-created if the previous instance fails due to an error. The instance is not re-created if the virtual machine stops successfully, such as when it shuts down.

Manual

The start, stop, and restart virtctl client commands can be used to control the VMI’s state and existence.

Halted

No VMI is present when a virtual machine is created, which is the same behavior as spec.running: false.

Different combinations of the start, stop and restart virtctl commands affect which RunStrategy is used.

The following table follows a VM’s transition from different states. The first column shows the VM’s initial RunStrategy. Each additional column shows a virtctl command and the new RunStrategy after that command is run.

Initial RunStrategy start stop restart

Always

-

Halted

Always

RerunOnFailure

-

Halted

RerunOnFailure

Manual

Manual

Manual

Manual

Halted

Always

-

-

In OKD Virtualization clusters installed using installer-provisioned infrastructure, when a node fails the MachineHealthCheck and becomes unavailable to the cluster, VMs with a RunStrategy of Always or RerunOnFailure are rescheduled on a new node.

 
apiVersion: kubevirt.io/v1
kind: VirtualMachine
spec:
  RunStrategy: Always (1)
  template:
# ...
1 The VMI’s current RunStrategy setting.

Additional resources