Thursday, December 4, 2025

Kubernetes : Create Virtual Machine

 

Kubernetes : Create Virtual Machine

 

Create a virtual machine with KubeVirt.

This example is based on the environment like follows.

+----------------------+   +----------------------+
|  [ ctrl.srv.world ]  |   |   [ dlp.srv.world ]  |
|     Manager Node     |   |     Control Plane    |
+-----------+----------+   +-----------+----------+
        eth0|10.0.0.25             eth0|10.0.0.30
            |                          |
------------+--------------------------+-----------
            |                          |
        eth0|10.0.0.51             eth0|10.0.0.52
+-----------+----------+   +-----------+----------+
| [ node01.srv.world ] |   | [ node02.srv.world ] |
|     Worker Node#1    |   |     Worker Node#2    |
+----------------------+   +----------------------+

[1]

A Persistent storage is needed to store OS images.
On this example, install NFS Server on a Node in local network and configure [/home/nfsshare] directory as NFS share as external persistent storage, and also configure dynamic volume provisioning with NFS plugin like the example of [1], [2], [3].

[2]Install Containerized Data Importer to store OS images.
debian@ctrl:~$ 
export TAG=$(curl -s -w %{redirect_url} https://github.com/kubevirt/containerized-data-importer/releases/latest)

debian@ctrl:~$ 
export VERSION=$(echo ${TAG##*/})

debian@ctrl:~$ 
wget https://github.com/kubevirt/containerized-data-importer/releases/download/${VERSION}/cdi-operator.yaml

debian@ctrl:~$ 
wget https://github.com/kubevirt/containerized-data-importer/releases/download/${VERSION}/cdi-cr.yaml
debian@ctrl:~$ 
vi cdi-cr.yaml
apiVersion: cdi.kubevirt.io/v1beta1
kind: CDI
metadata:
  name: cdi
spec:
  config:
    # add resource section to expand memory limits
    podResourceRequirements:
      limits:
        cpu: '1'
        memory: 4Gi
    featureGates:
    - HonorWaitForFirstConsumer
  imagePullPolicy: IfNotPresent
  infra:
    nodeSelector:
      kubernetes.io/os: linux
    tolerations:
    - key: CriticalAddonsOnly
      operator: Exists
  workload:
    nodeSelector:
      kubernetes.io/os: linux

debian@ctrl:~$ 
kubectl apply -f cdi-operator.yaml

namespace/cdi created
customresourcedefinition.apiextensions.k8s.io/cdis.cdi.kubevirt.io created
clusterrole.rbac.authorization.k8s.io/cdi-operator-cluster created
clusterrolebinding.rbac.authorization.k8s.io/cdi-operator created
serviceaccount/cdi-operator created
role.rbac.authorization.k8s.io/cdi-operator created
rolebinding.rbac.authorization.k8s.io/cdi-operator created
deployment.apps/cdi-operator created

debian@ctrl:~$ 
kubectl apply -f cdi-cr.yaml

cdi.cdi.kubevirt.io/cdi created
# after a few minutes, the pods will start up as follows

debian@ctrl:~$ 
kubectl get pods -n cdi

NAME                              READY   STATUS    RESTARTS        AGE
cdi-apiserver-56f6589fc5-mmjqm    1/1     Running   1 (2m15s ago)   2m33s
cdi-deployment-7b9c6dd88c-l7qhf   1/1     Running   0               2m33s
cdi-operator-575d6ffd85-s749h     1/1     Running   0               2m52s
cdi-uploadproxy-8c64dc68c-rtv9h   1/1     Running   0               2m33s
[3]Create a virtual machine. On this example, create it with Debian.
debian@ctrl:~$ 
kubectl get sc

NAME         PROVISIONER                                                RECLAIMPOLICY   VOLUMEBINDINGMODE   ALLOWVOLUMEEXPANSION   AGE
nfs-client   cluster.local/nfs-client-nfs-subdir-external-provisioner   Delete          Immediate           true                   55m

# create PVC definition

debian@ctrl:~$ 
vi debian-pvc.yml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: "debian-pvc"
  labels:
    app: containerized-data-importer
  annotations:
    cdi.kubevirt.io/storage.import.endpoint: "https://cdimage.debian.org/images/cloud/trixie/latest/debian-13-generic-amd64.raw"
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
  storageClassName: nfs-client

debian@ctrl:~$ 
kubectl apply -f debian-pvc.yml

persistentvolumeclaim/debian-pvc created
debian@ctrl:~$ 
kubectl get pvc

NAME         STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   VOLUMEATTRIBUTESCLASS   AGE
debian-pvc   Bound    pvc-f043ad24-c5a4-4555-b49d-232b77875057   10Gi       RWO            nfs-client     <unset>                 8s

debian@ctrl:~$ 
kubectl get pods

NAME                  READY   STATUS    RESTARTS   AGE
importer-debian-pvc   1/1     Running   0          3s

# possible to see importing logs

debian@ctrl:~$ 
kubectl logs -f importer-debian-pvc

.....
.....
I0825 01:59:14.846077       1 data-processor.go:354] Expanding image size to: 10129244160
E0825 01:59:14.851996       1 prlimit.go:156] failed to kill the process; os: process already finished
I0825 01:59:14.852010       1 data-processor.go:266] Validating image
E0825 01:59:14.855600       1 prlimit.go:156] failed to kill the process; os: process already finished
I0825 01:59:14.857726       1 data-processor.go:260] New phase: Complete
I0825 01:59:14.857896       1 importer.go:231] {"scratchSpaceRequired":false,"preallocationApplied":false,"message":"Import Complete"}

# after finishing importing, importer pod will also finish

debian@ctrl:~$ 
kubectl get pods

No resources found in default namespace.
# create VM definition

debian@ctrl:~$ 
vi debian-vm.yml
apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  name: debian13
  labels:
    kubevirt.io/os: linux
spec:
  runStrategy: Halted
  template:
    spec:
      domain:
        cpu:
          cores: 2
        devices:
          disks:
          - disk:
              bus: virtio
            name: disk0
          - cdrom:
              bus: sata
              readonly: true
            name: cloudinitdisk
          interfaces:
          - name: default
            masquerade: {}
        machine:
          type: q35
        resources:
          requests:
            memory: 4096M
      networks:
      - name: default
        pod: {}
      volumes:
      - name: disk0
        persistentVolumeClaim:
          claimName: debian-pvc
      - cloudInitNoCloud:
          userData: |
            #cloud-config
            hostname: debian13
            ssh_pwauth: true
            disable_root: false
            chpasswd:
              list: |
                root:myrootpassword
                debian:userpassword
              expire: False
        name: cloudinitdisk

debian@ctrl:~$ 
kubectl apply -f debian-vm.yml

virtualmachine.kubevirt.io/debian13 created
debian@ctrl:~$ 
kubectl get vms

NAME       AGE   STATUS    READY
debian13   6s    Stopped   False

debian@ctrl:~$ virtctl start debian13 
VM debian13 was scheduled to start

debian@ctrl:~$ 
kubectl get vmi

NAME       AGE   PHASE     IP                NODENAME           READY
debian13   13s   Running   192.168.241.153   node02.srv.world   True

debian@ctrl:~$ virtctl console debian13 
Successfully connected to debian13 console. Press Ctrl+] or Ctrl+5 to exit console.

debian13 login: root
Password:
Linux debian13 6.12.41+deb13-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.41-1 (2025-08-12) x86_64

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
root@debian13:~#
# to go back to the Host's console, push Ctrl + ] key
# * same operation as virsh command


# connect to VM via ssh
debian@ctrl:~$ kubectl get pods 
NAME                           READY   STATUS    RESTARTS   AGE
virt-launcher-debian13-4lfmm   2/2     Running   0          32s

debian@ctrl:~$ kubectl port-forward pod/virt-launcher-debian13-4lfmm 2221:22 & 

debian@ctrl:~$ ssh debian@127.0.0.1 -p 2221 
Handling connection for 2221
The authenticity of host '[127.0.0.1]:2221 ([127.0.0.1]:2221)' can't be established.
ED25519 key fingerprint is SHA256:bc9jh0VgOxVNFIgmSVol7UKendQSROJDCl0n0UWSd5A.
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '[127.0.0.1]:2221' (ED25519) to the list of known hosts.
debian@127.0.0.1's password:
Linux debian13 6.12.41+deb13-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.41-1 (2025-08-12) x86_64

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
debian@debian13:~$

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