packer.io config files to go from pristine vanilla ubuntu 12.04 LTS to a docker.io and chef-enabled vagrant box The resulting image is still a bit large and doesn't yet follow all the vagrant conventions, but it's a start.

packer-bootstrap.sh

#!/bin/sh

## install software for the base box to come packaged with - these will always be updated with chef/pupput
apt-get -y update && apt-get -y upgrade
apt-get install -y linux-image-generic-lts-raring linux-headers-generic-lts-raring build-essential dkms rubygems lxc-docker zlib1g-dev libssl-dev libreadline6-dev libyaml-dev ruby1.8 curl wget git-core gcc g++ make autoconf python-software-properties screen puppet puppetmaster openssl-server

sudo /usr/bin/gem install chef ruby-shadow --no-ri --no-rdoc

## create the vagrant user
sudo useradd -d /home/vagrant -m vagrant -p vagrant

## setup the vagrant user groupex
mkdir -m 0711 /home/ubuntu/.ssh/
echo 'ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEA6NF8iallvQVp22WDkTkyrtvp9eWW6A8YVr+kz4TjGYe7gHzIw+niNltGEFHzD8+v1I2YJ6oXevct1YeS0o9HZyN1Q9qgCgzUFtdOKLv6IedplqoPkcmF0aYet2PkEDo3MlTBckFXPITAMzF8dJSIFo9D8HfdOV0IAdx4O7PtixWKn5y2hMNG0zQPyUecp4pzC6kivAIhyfHilFR61RGL+GPXQ2MWZWFYbAGjyiYJnAmCP3NOTd0jMZEnDkbUvxhMmBYSdETk1rRgm+R4LOzFUGaHqHDLKLX+FIPKcF96hrucXzcWyLbIbEgE98OHlnVYCzRdK8jlqm8tehUc9c9WhQ== vagrant insecure public key' > /home/ubuntu/.ssh/authorized_keys
sudo groupadd admin 
sudo usermod -G admin vagrant
echo '%admin ALL=(ALL) NOPASSWD: ALL' >> /etc/sudoers
echo 'UseDNS no' >> /etc/ssh/sshd_config

## install the vagrant public & private keys
mkdir /home/vagrant/.ssh/
cd /home/vagrant/.ssh
wget http://github.com/mitchellh/vagrant/raw/master/keys/vagrant
wget http://github.com/mitchellh/vagrant/raw/master/keys/vagrant.pub
mv vagrant.pub /home/vagrant/.ssh/authorized_keys

## install the vbox guest additions
mkdir /mnt/VBoxGuestAdditions
mount /home/ubuntu/VBoxGuestAdditions.iso /mnt/VBoxGuestAdditions
sh /mnt/VBoxGuestAdditions/VBoxLinuxAdditions.run

## clean up the install
apt-get dist-upgrade -y
apt-get clean

## cleanup the vbox guest additions
umount /mnt/VBoxGuestAdditions
rmdir /mnt/VBoxGuestAdditions
rm /home/ubuntu/VBoxGuestAdditions.iso

preseed.cfg

d-i debian-installer/locale string en_US.UTF-8

d-i console-setup/ask_detect boolean false

d-i keyboard-configuration/modelcode string pc105

d-i netcfg/choose_interface select auto
d-i netcfg/get_hostname string vagrant-precise64
d-i netcfg/get_domain string vagrant.com
d-i netcfg/wireless_wep string

d-i mirror/country string Great Britain
d-i mirror/http/mirror select gb.archive.ubuntu.com
d-i mirror/http/hostname string gb.archive.ubuntu.com
d-i mirror/http/directory string /ubuntu
d-i mirror/http/proxy string

d-i mirror/suite string precise

d-i clock-setup/utc boolean true
d-i time/zone string Europe/London
d-i clock-setup/ntp boolean true

d-i partman-auto/init_automatically_partition select biggest_free
d-i partman-auto/disk string /dev/sda
d-i partman-auto/method string regular
#d-i partman-auto/choose_recipe select atomic
d-i partman/default_filesystem string ext4
d-i partman-partitioning/confirm_write_new_label boolean true
d-i partman/choose_partition select finish
d-i partman/confirm boolean true
d-i partman/confirm_nooverwrite boolean true
d-i partman/mount_style select label

#d-i base-installer/kernel/image string linux-generic
#d-i base-installer/kernel/image string linux-generic-lts-raring

d-i passwd/user-fullname string Ubuntu User
d-i passwd/username string ubuntu
d-i passwd/user-password password ubuntu
d-i passwd/user-password-again password ubuntu
d-i user-setup/allow-password-weak boolean true
d-i user-setup/encrypt-home boolean false

# Add docker repository:
d-i apt-setup/local0/repository string \
    http://ppa.launchpad.net/dotcloud/lxc-docker/ubuntu precise main
d-i apt-setup/local0/comment string dotcloud-lxc-docker
d-i apt-setup/local0/source boolean true
d-i apt-setup/local0/key string \
    http://keyserver.ubuntu.com/pks/lookup?op=get&search=0xE61D797F63561DC6

tasksel tasksel/first multiselect standard
d-i pkgsel/include string openssh-server build-essential
d-i pkgsel/upgrade select full-upgrade
d-i pkgsel/install-language-support boolean false
# d-i pkgsel/language-packs multiselect en
# d-i pkgsel/update-policy select none
d-i pkgsel/update-policy select unattended-upgrades
d-i pkgsel/updatedb boolean true

d-i grub-installer/only_debian boolean true
d-i grub-installer/with_other_os boolean true

d-i finish-install/reboot_in_progress note

ubuntu-vagrant.json

{
    "builders": [
        {
            "type": "virtualbox",
            "guest_os_type": "Ubuntu_64",
            "iso_url": "http://releases.ubuntu.com/precise/ubuntu-12.04.2-server-amd64.iso",
            "iso_md5": "af5f788aee1b32c4b2634734309cc9e9",
            "ssh_username": "ubuntu",
            "ssh_password": "ubuntu",
            "ssh_wait_timeout": "2000s",
            "disk_size": 40000,
            "guest_additions_path": "",
            "http_directory": "configs/",
            "http_port_min": 8000,
            "http_port_max": 9000,
            "output_directory": "./boxout/",
            "boot_command": [
                "<esc><esc><enter><wait>",
                "/install/vmlinuz noapic ",
                "preseed/url=http://{{ .HTTPIP }}:{{ .HTTPPort }}/preseed.cfg ",
                "debian-installer=en_US auto locale=en_US kbd-chooser/method=gb ",
                "hostname=vagrant-precise64 ",
                "fb=false debconf/frontend=noninteractive ",
                "keyboard-configuration/modelcode=SKIP keyboard-configuration/layout=GB ",
                "keyboard-configuration/variant=GB console-setup/ask_detect=false ",
                "initrd=/install/initrd.gz -- <enter>"
            ]
        }
    ],
    "provisioners": [{
        "type": "shell",
        "script": "./configs/packer-bootstrap.sh",
        "execute_command" : "echo 'ubuntu' | sudo -S sh '{{ .Path }}'"
    }],
    "post-processors": [{
        "type": "vagrant",
        "vagrantfile_template": "configs/Vagrantfile_template" 
    }]
}