1. Documentation

Virtual Machine Creation

Virtual Machine Creation

Overview

The OpenShift’s template mechanism allows user to create a set of objects from a template. KubeVirt takes benefit from this template mechanism to create VirtualMachines.

In order to create a virtual machine via OpenShift CLI, you need to provide a template defining the corresponding object and its metadata.

!> Only VirtualMachine object is currently supported.

Example template

Here is an example template that defines an instance of the VirtualMachine object:

apiVersion: v1
kind: Template
metadata:
  name: fedora-vmi-template
  annotations:
    description: "OpenShift KubeVirt Fedora VM template"
    tags: "kubevirt,openshift,template,linux"
  labels:
    kubevirt.io/os: fedora27
    miq.github.io/kubevirt-is-vmi-template: "true"
objects:
- apiVersion: kubevirt.io/v1alpha2
  kind: VirtualMachine
  metadata:
    name: ${NAME}
    labels:
      kubevirt-vm: vm-${NAME}
  spec:
    template:
      metadata:
        labels:
          kubevirt-vm: vm-${NAME}
      spec:
        domain:
          cpu:
            cores: ${{CPU_CORES}}
          resources:
            requests:
              memory: ${{MEMORY}}
          devices:
            disks:
              - name: disk0
                volumeName: root
        volumes:
          - name: root
            persistentVolumeClaim:
              claimName: myroot
parameters:
- name: NAME
  description: Name for the new VM
- name: CPU_CORES
  description: Amount of cores
  value: "4"

Note that the template above defines free parameters (NAME and CPU_CORES) and the NAME parameter does not have specified default value.

An OpenShift template has to be converted into the JSON file via oc process command, that also allows you to set the template parameters.

A complete example can be found in the KubeVirt repository.

!> You need to be logged in by oc login command.

$ oc process -f cluster/vmi-template-fedora.yaml\
    -p NAME=testvmi \
    -p CPU_CORES=2
{
    "kind": "List",
    "apiVersion": "v1",
    "metadata": {},
    "items": [
        {
...

The JSON file is usually applied directly by piping the processed output to oc create command.

$ oc process -f cluster/vmi-template-fedora.yaml \
    -p NAME=testvmi \
    -p CPU_CORES=2 \
    | oc create -f -
virtualmachine "testvmi" created

The command above results in creating a Kubernetes object according to the specification given by the template (in this example it is an instance of the VirtualMachine object).

Starting virtual machine from the created object

The created object is now a regular VirtualMachine object and from now it can be controlled by accessing Kubernetes API resources. The preferred way how to do this from within the OpenShift environment is to use oc patch command.

$ oc patch virtualmachine testvmi --type merge -p '{"spec":{"running":true}}'
virtualmachine "testvmi" patched

You can follow Virtual Machine Lifecycle Guide for further reference.