How to create an image from scratch

apt-get update
apt-get install debootstrap

#!/bin/bash

# Name  of  the  bootstrap  script variant to use.
# Currently, the variants supported are minbase,
# which  only  includes  essentialpackages  and  apt;  buildd,
# which installs the build-essential
# packages  into  TARGET;  and  fakechroot,  which  installs   the
# packages  without  root  privileges.   Finally  there is variant
# scratchbox, which is for creating targets for scratchbox  usage.
#  The  default,  with no --variant=X argument, is to create a base
VARIANT=minbase

# The system architecture, C1 server architecture type is armhf
ARCH=armhf

# Use packages from the listed components of the archive.
COMPONENTS=main,universe

# The volume to boostrap the system
DEBOOTSTRAP_DIR=/mnt/ubuntu-tpl/

# The list of packages included in the system

PKGS_INCLUDE='ca-certificates, cron, curl, iptables, iputils-ping, isc-dhcp-client, less,libnss-myhostname, man-db, nano, nbd-client, net-tools, ntp, ntpdate, rsyslog, ssh, sudo, vim, wget, whiptail, xnbd-client'

MIRROR=http://mirror.cloud.online.net/ubuntu-ports/

DEVICE=/dev/nbd1

# Check if directory DEBOOTSTRAP_DIR exists
if [ ! -d "$DEBOOTSTRAP_DIR" ]; then
  mkdir -p $DEBOOTSTRAP_DIR
fi

# Format /dev/nbdx volume


# Format & Mount /dev/nbdx in #DEBOOTSTRAP_DIR
if [ ! `mountpoint -q $DEBOOTSTRAP_DIR` ]; then
  mkfs.ext4 $DEVICE
  mount $DEVICE $DEBOOTSTRAP_DIR
fi

# Bootstrap a basic Ubuntu trusty system
 debootstrap --arch $ARCH --variant=$VARIANT --components "$COMPONENTS" --include "$PKGS_INCLUDE" trusty $DEBOOTSTRAP_DIR "$MIRROR"

for i in {1..6}
do
  echo manual > $DEBOOTSTRAP_DIR/etc/init/tty$i.override
done

# The list of files required to copy on the template

# Upstart job - Maintains a getty on ttyS0
FILES_TO_COPY="/etc/init/ttyS0.conf"

# Upstart job - Fetches ssh-keys associated with your account in `/root/.authorized_keys`
FILES_TO_COPY+=" /etc/init/ssh-keys.conf"

# Upstart job - Preserves the NBD client process on shutdown
FILES_TO_COPY+=" /etc/init/nbd-root-preserve-client.conf"

# Upstart job - Gracefully umount and disconnect root volume
FILES_TO_COPY+=" /etc/init/nbd-root-disconnect.conf"

# Upstart job - Connects additional volumes to NBD server
FILES_TO_COPY+=" /etc/init/nbd-add-extra-volumes.conf"

# Upstart job - Synchronizes kernel modules
FILES_TO_COPY+=" /etc/init/sync-kernel-modules.conf"

# This script is required by `/nbd-root-disconnect.conf` to disconnect root volume gracefully.
FILES_TO_COPY+=" /usr/sbin/nbd-disconnect-root"

# Variables for the behavior of boot scripts
FILES_TO_COPY+=" /etc/default/rcS"

# ntpd service configuration with appropriate NTP servers
FILES_TO_COPY+=" /etc/ntp.conf"

# Map some hostnames to IP addresses before DNS can be referenced.
FILES_TO_COPY+=" /etc/hosts"

# Kernel options related on C1 server
FILES_TO_COPY+=" /etc/sysctl.conf"

# Network interfaces configuration
FILES_TO_COPY+=" /etc/network/interfaces"

# Executable which synchronizes kernel modules
FILES_TO_COPY+=" /usr/sbin/oc-sync-kernel-modules"

# Executable which retrieves server metadata (TEXT)
FILES_TO_COPY+=" /usr/local/bin/oc-metadata"

# Executable which retrieves server metadata (JSON)
FILES_TO_COPY+=" /usr/local/bin/oc-metadata-json"

# DHCP hook
FILES_TO_COPY+=" /etc/dhcp/dhclient-exit-hooks.d/hostname"

# Copy files above in the appropriate directory
for FILE in ${FILES_TO_COPY}
do
  cp ${FILE} ${DEBOOTSTRAP_DIR}${FILE}
done

umount $DEBOOTSTRAP_DIR