================ build.json============================



{
  "Variables": {
    "domain": "local",
    "hostname": "ubuntu",
    "ssh_pass": "test",
    "ssh_user": "test"
  },
  "builders": [
    {
      "boot_command": [
        "<enter><wait><f6><esc><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs>",
        "<bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs>",
        "<bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs>",
        "<bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs><bs>",
        "/install/vmlinuz<wait>",
        "auto<wait>",
        " console-setup/ask_detect=false<wait>",
        " console-setup/layoutcode=us<wait>",
        " console-setup/modelcode=105<wait>",
        " debconf/frontend=noninteractive<wait>",
        " deian-installer=en_US<wait>",
        " fb=false<wait>",
        " initrd=/install/initrd.gz<wait>",
        " kdb-chooser/method=us<wait>",
        " keyoard-configuration/layout=USA<wait>",
        " keyoard-configuration/variant=USA<wait>",
        " locale=en_US<wait>",
        " netcfg/get_domain={{user `domain`}}<wait>",
        " netcfg/get_hostname={{user `hostname`}}<wait>",
        " grub-installer/bootdev=/dev/sda/<wait>",
        " noapic<wait>",
        " preseed/url=http:/{{ .HTTPIP }}:{{ .HTTPPort }}/preseed.cfg",
        " -- <wait>",
        " <enter> <wait>"
      ],
      "cpus": "1",
      "disk_size": "20000",
      "format": "ova",
      "guest_additions_mode": "upload",
      "guest_os_type": "ubuntu_64",
      "headless": "false",
      "http_directory": "http",
      "iso_checksum": "md5:2b0bfcb7e9e95c8eadb14a6fb59efae8",
      "iso_target_path": "/home/ubuntu/t/packer/ubuntu-20.04.2.0-desktop-amd64.iso",
      "iso_url": "https://releases.ubuntu.com/20.04/ubuntu-20.04.2.0-desktop-amd64.iso",
      "output_directory": "ubuntu-20.04",
      "memory": "1024",
      "shutdown_command": "sudo /sbin/halt -p",
      "ssh_password": "{{user `ssh_pass`}}",
      "ssh_pty": "true",
      "ssh_timeout": "5h",
      "ssh_handshake_attempts": "100",
      "ssh_username": "{{user `ssh_user`}}",
      "type": "virtualbox-iso",
      "vm_name": "Test_VM"
    }
  ],
  "provisioners": [{
      "type" : "shell",
      "expect_disconnect": "true",
      "pause_after": "120s",
      "execute_command": "echo '{{ user `ssh_pass` }}' | {{.Vars}} sudo -E -S bash '{{.Path}}'",
      "scripts": "scripts/init.sh"
    },
    {
      "type": "shell",
      "execute_command": "echo '{{user `ssh_pass` }}' | {{.Vars}} sudo -E -S bash '{{.Path}}'",
      "scripts": [
            "scripts/revtools.sh"]
    }]
}

===========================================preceed.cfg===============================




# Supported locales available in /usr/share/i18n/SUPPORTED
d-i debian-installer/language string en
d-i debian-installer/locale string en_US.UTF-8
d-i localechooser/preferred-locale string en_US.UTF-8
d-i localechooser/supported-locales en_US.UTF-8

# Hostname / domain
d-i netcfg/get_hostname string ubuntu
d-i netcfg/get_domain string local

# Keyboard setting
d-i console-setup/ask_detect boolean false
d-i keyboard-configuration/layout selecct USA
d-i keyboard-configuration/variant select USA
d-i keyboard-configuration/modelcode string pc105

# Timezoon /Time
d-i time/zone string UTC
d-i clock-setup/utc-auto boolean true
d-i clock-setup/utc boolean true

# Server
tasksel tasksel/first multiselect standard, ubuntu-server

# No proxy
d -i mirror/http/proxy string

# Package Policy
d-i pkgsel/install-language-support boolean false
d-i pkgsel/update-policy select none
d-i pkgsel/upgrade select full-upgrade
d-i pkgsel/include string openssh-server cryptsetup build-essential libssl-dev libreadline-dev zlib1g-dev

# Partitioning
d-i partman-auto/method string lvm
d-i partman-auto-lvm/guided_size string max
d-i partman-auto/choose_recipe select atomic
d-i partman-auto/disk string /dev/sda
d-i partman-lvm/confirm boolean true
d-i partman-lvm/confirm_nooverwrite boolean true
d-i partman/confirm boolean true
d-i partman/confirm_write_new_label boolean true
d-i partman/choose_partition select finish

# Creat packer user account
d-i passwd/user-fullname string packer
d-i passwd/username string test
d-i passwd/user-password password test
d-i passwd/user-password-again password test
d-i user-setup/allow-password-weak boolean true
d-i user-setup/encrypt-home boolean false
d-i passwd/user-default-group packer sudo