Startup Scripts

KubeVirt supports the ability to assign a startup script to a VMI instance which is executed automatically when the VM initializes.

These scripts are commonly used to automate injection of users and SSH keys into VMs in order to provide remote access to the machine. For example, a startup script can be used to inject credentials into a VM that allows an Ansible job running on a remote host to access and provision the VM.

Startup scripts are not limited to any specific use case though. They can be used to run any arbitrary script in a VM on boot.

Example of use:

Assign static IP using cloudInitNoCloud.

apiVersion: kubevirt.io/v1
kind: VirtualMachine
metadata:
  labels:
    special: vmi-sriov-network
  name: vmi-sriov-network
spec:
  running: true
  template:
    metadata:
      labels:
        kubevirt.io/size: small
        kubevirt.io/domain: fedora
    spec:
      domain:
        cpu:
          cores: 4
        devices:
          disks:
          - name: containerdisk
            disk:
              bus: virtio
          - name: cloudinitdisk
            disk:
              bus: virtio
          interfaces:
          - masquerade: {}
            name: default
          - macAddress: "02:00:00:00:00:01"
            name: sriov-net1
            sriov: {}
          rng: {}
        resources:
          requests:
            memory: 1024M
      networks:
      - name: default
        pod: {}
      - multus:
          networkName: sriov-net1
        name: sriov-net1
      volumes:
      - containerDisk:
          image: docker.io/kubevirt/fedora-cloud-container-disk-demo:devel
        name: containerdisk
      - cloudInitNoCloud:
          networkData: |
            ethernets:
              sriov-net1:
                addresses:
                - 10.10.10.14/24
                gateway: 10.10.10.1
                match:
                  macAddress: "02:00:00:00:00:01"
                nameservers:
                  addresses:
                  - 10.96.0.10
                  search:
                  - default.svc.cluster.local
                  - svc.cluster.local
                set-name: sriov-link-enabled
                                   version: 2
              #          userData: '#!/bin/bash echo "fedora" | passwd fedora --stdin'
          userData: |-
            #!/bin/bash
            echo "fedora" |passwd fedora --stdin
        name: cloudinitdisk