kubevirt: Support nocloud user-data

[qinqon]

At kubevirt one can configure the cloud init as config drive or nocloud, with config drive is the current approch, this change add the nocloud that spect a device mount with "cidata" label and tue user data file at /user-data there, also the main different if that on those cases the network data follows the netplan v1 or v2 that's is better format than the openstack meta data network service one.

[gemini-code-assist]

Code Review

This pull request adds support for nocloud user-data in Kubevirt, falling back to the existing config-drive method. The changes are well-structured, particularly the parameterization of the device and path fetching logic. I've identified a potential logic issue in the new fallback mechanism: if the nocloud source provides no user data, the fallback to config-drive is not triggered. I have included a specific comment with a suggested fix for this behavior.

[jlebon]

Seems sane to me. Needs release note.

[qinqon]

Seems sane to me. Needs release note.

@jlebon thanks on it!

[qinqon]

Humm something is not ready yet it's failing to find cidata with this VM

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  namespace: clusters-test1
  name: fedora-coreos-vm
spec:
  runStrategy: Always
  template:
    metadata:
      labels:
        app: fedora-coreos-vm
    spec:
      domain:
        devices:
          disks:
            - name: rootdisk
              disk:
                bus: virtio
            - name: cloudinitdisk
              disk:
                bus: virtio
          interfaces:
            - name: default
              bridge: {}
        resources:
          requests:
            memory: 2Gi
            cpu: "1"
          limits:
            memory: 4Gi
            cpu: "2"
      networks:
        - name: default
          multus:
            networkName: localnet-clusters-test1
      volumes:
        - name: rootdisk
          containerDisk:
            image: quay.io/ellorent/fcos-kubevirt@sha256:410995a0d71a0ff73809fb5872a66da396e6ea51321bb6f790885610605473d8
        - name: cloudinitdisk
          cloudInitNoCloud:
            userData: '{"ignition":{"version":"3.5.0"},"passwd":{"users":[{"name":"core","passwordHash":"$y$j9T$b7RFf2LW7MUOiF4RyLHKA0$T.Ap/uzmg8zrTcUNXyXvBvT26UgkC6zZUVg3UKXeEp5"}]}}'

I am building it with https://github.com/qinqon/coreos-initrd-builder

And I can confirm that the ignition inside the VM is the custom one.

[   12.595697] ignition[776]: Ignition 2.21.0
[   12.595811] ignition[776]: Stage: fetch-offline
[   12.595869] ignition[776]: reading system config file "/usr/lib/ignition/base.d/00-core.ign"
[   12.599678] ignition[776]: reading system config file "/usr/lib/ignition/base.d/30-afterburn-sshkeys-core.ign"
[   12.602698] ignition[776]: no config dir at "/usr/lib/ignition/base.platform.d/kubevirt"
[   12.602851] ignition[776]: no config URL provided
[   12.602925] ignition[776]: reading system config file "/usr/lib/ignition/user.ign"
[   12.602997] ignition[776]: no config at "/usr/lib/ignition/user.ign"
[   12.804951] systemd[1]: Finished systemd-vconsole-setup.service - Virtual Console Setup.

[qinqon]

@jlebon @prestist managed to test it and it's working fine, kubevirt fecos with ConfigDrive and NoCloud is working as expected.

Tested it with images builded with https://github.com/qinqon/coreos-initrd-builder
These are the kubevirt VMs

With NoCloud

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  namespace: clusters-test1
  name: fedora-coreos-vm
spec:
  runStrategy: Always
  template:
    metadata:
      labels:
        app: fedora-coreos-vm
    spec:
      domain:
        devices:
          disks:
            - name: rootdisk
              disk:
                bus: virtio
            - name: cloudinitdisk
              disk:
                bus: virtio
          interfaces:
            - name: default
              bridge: {}
        resources:
          requests:
            memory: 2Gi
            cpu: "1"
          limits:
            memory: 4Gi
            cpu: "2"
      networks:
        - name: default
          multus:
            networkName: localnet-clusters-test1
      volumes:
        - name: rootdisk
          containerDisk:
            image: quay.io/ellorent/fcos-kubevirt@sha256:a773c47ecff9f580a80510d0e4c652c5648b1cb102ec16832b68ba925a810114
        - name: cloudinitdisk
          cloudInitNoCloud:
            userData: '{"ignition":{"version":"3.5.0"},"passwd":{"users":[{"name":"core","passwordHash":"$y$j9T$b7RFf2LW7MUOiF4RyLHKA0$T.Ap/uzmg8zrTcUNXyXvBvT26UgkC6zZUVg3UKXeEp5"}]}}'

And with ConfigDrive

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  namespace: clusters-test1
  name: fedora-coreos-vm
spec:
  runStrategy: Always
  template:
    metadata:
      labels:
        app: fedora-coreos-vm
    spec:
      domain:
        devices:
          disks:
            - name: rootdisk
              disk:
                bus: virtio
            - name: cloudinitdisk
              disk:
                bus: virtio
          interfaces:
            - name: default
              bridge: {}
        resources:
          requests:
            memory: 2Gi
            cpu: "1"
          limits:
            memory: 4Gi
            cpu: "2"
      networks:
        - name: default
          multus:
            networkName: localnet-clusters-test1
      volumes:
        - name: rootdisk
          containerDisk:
            image: quay.io/ellorent/fcos-kubevirt@sha256:a773c47ecff9f580a80510d0e4c652c5648b1cb102ec16832b68ba925a810114
        - name: cloudinitdisk
          cloudInitConfigDrive:
            userData: '{"ignition":{"version":"3.5.0"},"passwd":{"users":[{"name":"core","passwordHash":"$y$j9T$b7RFf2LW7MUOiF4RyLHKA0$T.Ap/uzmg8zrTcUNXyXvBvT26UgkC6zZUVg3UKXeEp5"}]}}'

[prestist]

Overall LGTM just that one nit.

[prestist]

Thank you for working on this, and being so quick to respond to feedback LGTM!