Add KubeVirt platform support

[rmohr]

KubeVirt always exposes instance_id and hostname. Optionally ssh
keys may be provided by the platform matadata.

xref coreos/fedora-coreos-tracker#1126

Copying the resulting binary in a fcos VM on kubevirt yields this:

[core@vmi-fedora ~]$ sudo ./afterburn --provider kubevirt --hostname blub
Mar 25 11:17:47.276 INFO wrote hostname vmi-fedora to blub
[core@vmi-fedora ~]$ cat blub 
vmi-fedora
[core@vmi-fedora ~]$ sudo ./afterburn --provider kubevirt --attributes attrs
[core@vmi-fedora ~]$ cat attrs 
AFTERBURN_KUBEVIRT_INSTANCE_TYPE=myflavour
AFTERBURN_KUBEVIRT_INSTANCE_ID=8b5ea8f7-f7f2-48c8-a471-9a687302eb65
AFTERBURN_KUBEVIRT_HOSTNAME=vmi-fedora
[core@vmi-fedora ~]$ rm /home/core/.ssh/authorized_keys.d/afterburn
[core@vmi-fedora ~]$ sudo ./afterburn --provider kubevirt --ssh-keys core
[core@vmi-fedora ~]$ cat /home/core/.ssh/authorized_keys.d/afterburn
ssh-rsa AAAAB3...

For reference the VMI spec used to let kubevirt inject the data:

---
apiVersion: kubevirt.io/v1
kind: VirtualMachineInstance
metadata:
  labels:
    special: vmi-fedora
  name: vmi-fedora
spec:
  domain:
    devices:
      disks:
      - disk:
          bus: virtio
        name: containerdisk
      - disk:
          bus: virtio
        name: cloudinitdisk
      rng: {}
    resources:
      requests:
        memory: 1024M
  terminationGracePeriodSeconds: 0
  accessCredentials:
  - sshPublicKey:
      source:
        secret:
          secretName: my-pub-key
      propagationMethod:
        configDrive: {}
  volumes:
  - containerDisk:
      image: quay.io/rmohr/rhcostest:35.20220316.dev.0-x86_64
    name: containerdisk
  - name: cloudinitdisk
    cloudInitConfigDrive:
      userData: |-
        {
          "ignition": {
            "version": "3.3.0"
          },
          "passwd": {
            "users": [
              {
                "name": "core",
                "sshAuthorizedKeys": [
                  "ssh-rsa AAAAB3..."
                ]
              }
            ]
          }
        }

This part

  - sshPublicKey:
      source:
        secret:
          secretName: my-pub-key
      propagationMethod:
        configDrive: {}

is responsible for injecting via config-drive metadata the ssh public keys in the secret my-pub-key.

[rmohr]

/cc @bgilbert

[bgilbert]

LGTM generally; two tiny nits and a question.

[bgilbert]

Looks good!

[bgilbert]

Also, looks like mod.rs needs to be reformatted.

[rmohr]

Also, looks like mod.rs needs to be reformatted.

Hm, neiter cargo fmt, nor rustfmt produced any diff. cargo fmt -- --check -l returns locally for me with 0 exit code. Tried versions 1.59.0 and 1.57.0 (the one in the github workflow?) and 1.49.0 :/

[rmohr]

@bgilbert could you allow CI to run? It may help me with the fmt issue which you raised.

[bgilbert]

Weird, tests seem happy now.