base_vm.json

{
  "variables" : {
    "user": "clover",
    "password": "clover",
    "vm-name": "clover-devel"
  },
  "builders": [{
    "type": "virtualbox-iso",
    "vm_name": "{{user `vm-name`}}",
    "guest_os_type": "Ubuntu_64",
    "format": "ova",
    "guest_additions_mode": "disable",
    "disk_size": "30000",
    "hard_drive_interface": "sata",
    "vboxmanage": [
      ["modifyvm", "{{.Name}}", "--memory", "2048", "--mouse", "usbtablet", "--apic", "on", "--rtcuseutc", "on", "--nictype1", "virtio"],
      ["storageattach", "{{.Name}}", "--storagectl", "SATA Controller", "--port", "0", "--nonrotational", "on", "--discard", "on"]
    ],

    "headless": "false",

    "iso_url": "http://archive.ubuntu.com/ubuntu/dists/focal/main/installer-amd64/current/legacy-images/netboot/mini.iso",
    "iso_checksum": "0e79e00bf844929d40825b1f0e8634415cda195ba23bae0b041911fde4dfe018",
    "iso_checksum_type": "sha256",

    "ssh_password": "{{user `password`}}",
    "ssh_username": "{{user `user`}}",
    "ssh_wait_timeout": "10000s",

    "boot_command": [
      "<esc><wait>",
      "install auto=true priority=critical url=http://{{.HTTPIP}}:{{.HTTPPort}}/preseed.cfg",
      "<enter><wait>"
    ],

    "boot_wait": "4s",
    "http_directory": "http",
    "shutdown_command": "echo {{user `password`}} | sudo -S shutdown -P now",

    "vboxmanage_post": [
      ["modifyhd", "output-virtualbox-iso/{{.Name}}.vdi", "--compact"]
    ]
  }]
}