ubuntu2004.json

{
  "builders": [
    {
      "boot_command": [
        "<enter><wait2><enter><wait><f6><esc><wait>",
        " autoinstall<wait2> ds=nocloud-net;",
        "<wait><enter>"
      ],
      "boot_wait": "3s",
      "cpus": 4,
      "memory": 4096,
      "guest_os_type": "Ubuntu_64",
      "headless": false,
      "http_directory": "./http",
      "iso_checksum": "sha256:443511f6bf12402c12503733059269a2e10dec602916c0a75263e5d990f6bb93",
      "iso_url": "https://releases.ubuntu.com/20.04/ubuntu-20.04.1-live-server-amd64.iso",
      "name": "ubuntu-2004",
      "ssh_timeout": "10000s",
      "floppy_files": ["./http/user-data", "./http/meta-data"],
      "floppy_label": "cidata",
      "ssh_handshake_attempts": "100",
      "ssh_username": "ubuntu",
      "ssh_password": "ubuntu",
      "type": "virtualbox-iso"
    }
  ],
  "provisioners": [
    {
      "inline": [
        "ls /"
      ],
      "type": "shell"
    }
  ]
}

user-data

#cloud-config
autoinstall:
  version: 1
  locale: en_GB
  keyboard:
    layout: en
    variant: uk
  network:
    network:
      version: 2
      ethernets:
        enp0s3:
          dhcp4: true
  identity:
    hostname: ubuntu-server
    username: ubuntu
    password: $6$E.3LG7StnEURoOWy$PTcyaJyS5HHFExctu5hWd.oH0LapJ9gXzUd62QfVDjza4rfrEy61NVLmlGE40R7eSBvWBkISvRabc2y0NQ/sy0
  ssh:
    install-server: yes
  user-data:
    disable_root: false
  late-commands:
    - 'sed -i "s/dhcp4: true/&\n      dhcp-identifier: mac/" /target/etc/netplan/00-installer-config.yaml'
    - echo 'ubuntu ALL=(ALL) NOPASSWD:ALL' > /target/etc/sudoers.d/ubuntu