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