template.json

{
  "variables": {
    "fullname": "Vagrant",
    "username": "vagrant",
    "password": "vagrant"
  },

  "builders": [
    {
      "type": "virtualbox-iso",
      "guest_os_type": "Debian_64",
      "disk_size": 10000,
      "vboxmanage": [
        ["modifyvm", "{{.Name}}", "--memory", "1024"],
	["modifyvm", "{{.Name}}", "--cpus", "2"]
      ],
      "iso_url": "http://d-i.debian.org/daily-images/amd64/daily/netboot/mini.iso",
      "iso_checksum": "899a47cec16a488743d053c8f3624a6e",
      "iso_url": http://d-i.debian.org/daily-images/amd64/daily/netboot/MD5SUMS,
      "iso_checksum_type": "md5",
      "http_directory": "http",
      "ssh_username": "{{user `username`}}",
      "ssh_password": "{{user `password`}}",
      "ssh_wait_timeout": "360m",
      "shutdown_command": "echo '{{user `password`}}' | sudo -S halt -p",
      "headless": true,
      "boot_wait": "5s",
      "boot_command": [
        "<esc><wait>",
        "auto url=http://{{ .HTTPIP }}:{{ .HTTPPort }}/preseed.cfg ",
        "passwd/user-fullname={{user `fullname`}} ",
        "passwd/username={{user `username`}} ",
        "passwd/user-password={{user `password`}} ",
        "passwd/user-password-again={{user `password`}} ",
        "<enter>"
      ]
    }
  ],

  "provisioners": [
    {
      "type": "shell",
      "scripts": [
        "scripts/vagrant.sh",
        "scripts/virtualbox.sh",
        "scripts/ansible.sh",
        "scripts/zerodisk.sh"
      ],
      "execute_command": "echo '{{user `password`}}' | {{ .Vars }} sudo -E -S sh '{{ .Path }}'"
    }
  ],

  "post-processors": [
    {
      "type": "vagrant",
      "output": "packer_debian-unstable_{{.Provider}}.box",
      "keep_input_artifact": true
    }
  ]
}