Hello World KubeVirt VM

About this task

This section provides a ‘hello world’ example of creating, running and attaching to a VM with KubeVirt. The example uses

  • A CirrOS image packaged as a Container Image and available from docker.io:kubevirt/cirros-container-disk-demo:latest

  • A ‘containerDisk’ volume type

    • The containerDisk feature provides the ability to store and distribute VM disks in a container image registry.

    • containerDisks can be assigned to VMs in the disks section of the VirtualMachine spec.

    • containerDisks are ephemeral storage devices; so can they only be used by applications that do NOT require persistent data.

  • A cloudInitNoCloud volume type, which allows attaching cloudInitNoCloud data-sources to the VM. If the VM contains a proper cloud-init setup, it will pick up the disk as a user-data source.

  • No additional network interfaces other than the default CNI interface of the container running the VM.

  • Connect with either the serial console interface via virtctl, or through a NodePort service on the StarlingX Floating OAM IP Address.

Procedure

Complete the procedure below to create the VM, start the VM and login into the VM via the console:

  1. Create the yaml file defining the VirtualMachine CRD instance.

    apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  labels:
    kubevirt.io/vm: vm-cirros
  name: vm-cirros
spec:
  running: false
  template:
    metadata:
      labels:
        kubevirt.io/vm: vm-cirros
spec:
  domain:
    devices:
      disks:
      -disk:
         bus: virtio
      - name: containerdisk
        disk:
          bus: virtio
      - name: cloudinitdisk
        disk:
          bus: virtio
    resources:
      requests:
        memory: 64M
  terminationGracePeriodSeconds: 0
  volumes:
    - name: containerdisk
      containerDisk:
        image: kubevirt/cirros-container-disk-demo:latest
    - name: cloudinitdisk
      cloudInitNoCloud:
        userDataBase64: IyEvYmluL3NoCmVjaG8gJ3ByaW50ZWQgZnJvbSBjbG91ZC1pbml0IHVzZXJkYXRhJwo=

  2. Apply the yaml file to create the VM in a stopped state.

    $ kubectl apply -f vm-cirros-containerdisk.yaml

$ kubectl get vm
NAME      AGE STATUS  READY
vm-cirros 17s Stopped False

$ kubectl get vmi
No resources found in default namespace.

  3. Start the VM with the virtctl tool.

    $ virtctl start vm-cirros
VM vm-cirros was scheduled to start

$ kubectl get vm
NAME         AGE  STATUS   READY
vm-cirro     87s  Running  True

$ kubectl get vmi
NAME         AGE PHASE   IP               NODENAME    READY
vm-cirros    17s Running 172.16.225.72    compute-2   True

  4. Connect to and login into the VM console using the virtctl tool.

    $ virtctl console vm-cirros
Successfully connected to vm-cirros console. The escape sequence is ^]

# login as 'cirros' user. default password: 'gocubsgo'. Use 'sudo' for root.
# vm-cirros login: cirros
Password:

$ ls /
  bin       home           lib64          mnt         root        tmp
  boot      init           linuxrc        old-root    run         usr
  dev       initrd.img     lost+found     opt         sbin        var
  etc       lib            media          proc        sys         vmlinuz

$ ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000 link/ether a6:77:37:4c:ee:10 brd ff:ff:ff:ff:ff:ff

# List Interfaces
# Notice how the VM has a single eth0 interface, the default CNI interface.

$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever inet6 ::1/128 scope host

valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000 link/ether a6:77:37:4c:ee:10 brd ff:ff:ff:ff:ff:ff
inet 172.16.225.72/32 brd 172.16.255.255 scope global eth0
valid_lft forever preferred_lft forever inet6 fe80::a477:37ff:fe4c:ee10/64 scope link valid_lft forever preferred_lft forever
# Exit/escape from the VM Console with ctrl+']'
$ ^]

  5. Expose the SSH port of vm-cirros via a NodePort.

    $ virtctl expose vmi vm-cirros --port=22 --name vm-cirros-ssh --type=NodePort
Service vm-cirros-ssh successfully exposed for vmi vm-cirros

$ kubectl get service
NAME            TYPE      CLUSTER-IP     EXTERNAL-IP PORT(S)       AGE
kuard-nodeport NodePort   10.96.155.165 <none>       80:31118/TCP 92d
kubernetes      ClusterIP 10.96.0.1      <none>       443/TCP       188d
nodeinfo        ClusterIP 10.96.189.47   <none>       1080/TCP      92d
vm-cirros-ssh   NodePort  10.99.91.228   <none>       22:31562/TCP 9s

  6. Connect from a remote workstation.

    $ ssh -p 31562 cirros@<Floating-OAM-IP-Address-of-StarlingX>
password:

# List Interfaces
# Notice how the VM has a single eth0 interface, the default CNI interface.

$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue qlen 1
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
      valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
      valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
    link/ether a6:77:37:4c:ee:10 brd ff:ff:ff:ff:ff:ff
    inet 172.16.225.72/32 brd 172.16.255.255 scope global eth0
      valid_lft forever preferred_lft forever
    inet6 fe80::a477:37ff:fe4c:ee10/64 scope link
      valid_lft forever preferred_lft forever

$ exit