Make a unattended installation of Ubuntu server image

In this post we see how I investigated to find the target preseed file matches my requirement. This post shows the step-by-step commands in summary.

Firstly let's fetch the iso contents from the original iso image.

$ sudo mount -o loop ~/Desktop/images/ubuntu-16.04.1-server-amd64.iso ./160401-base-iso/
mount: /dev/loop6 is write-protected, mounting read-only
$ cp -rT ./160401-base-iso/ ./160401-target-iso/
$ sudo umount ~/Desktop/images/ubuntu-16.04.1-server-amd64.iso

Then let's tweak isolinux, which is used to boot the system at the very first time, a bit:

$ chmod u+w 160401-target-iso/isolinux/txt.cfg
$ vi 160401-target-iso/isolinux/txt.cfg

You may want to use the txt.cfg directly from here https://gist.github.com/tai271828/cbe426c158c68ae8f51a18b0ad26af52#file-txt-cfg

and

default install
label install
  menu label ^Install Ubuntu Server
  kernel /install/vmlinuz
  append  file=/cdrom/preseed/unattended-ubuntu-server.seed vga=788 initrd=/install/initrd.gz quiet languagechooser/language-name=English debian-installer/locale=en_US keyboard-configuration/layoutcode=us ---

You may also want to use the isolinux.cfg here as well https://gist.github.com/tai271828/cbe426c158c68ae8f51a18b0ad26af52#file-isolinux-cfg

$ chmod u+w 160401-target-iso/isolinux/isolinux.cfg
$ vi 160401-target-iso/isolinux/isolinux.cfg

set timeout as 1 (or any positive integer. 0 means waiting forever)

Lastly let's put the preseed, unattended-ubuntu-server.seed

,  pointed by txt.cfg. Please check the details of the preseed file here: https://gist.github.com/tai271828/cbe426c158c68ae8f51a18b0ad26af52#file-unattended-ubuntu-server-seed

Everything is ready! Let's generate the iso. Under the target iso folder

sudo mkisofs -r -V "UBUNTU160401" -cache-inodes -J -l -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -o ~/Desktop/images/ubuntu-16.04.1-server-amd64-autoinstall.iso .

The above steps are wrapped up here https://gist.github.com/tai271828/cbe426c158c68ae8f51a18b0ad26af52#file-prepare-image-sh Tweak it to match your file hierarchy.

PS Ubuntu server by default has no tty7 (used for X to provide GUI conventionally) and use tty1.

What is Next...

The final product is an iso. You could boot it from virt-manager easily by using it as a virtual CD-ROM disk. However, in the modern world, we use live USB much more often now. To make a bootable live USB of this iso, you may achieve the goal by

sudo isohybrid ubuntu-16.04.1-server-amd64-autoinstall.iso
sudo dd bs=4M if=./ubuntu-16.04.1-server-amd64-autoinstall.iso of=/dev/sdX conv=fdatasync

How and why isohubrid works you could refer to my another blog post in Chinese http://zh-tw-tai271828.blogspot.tw/2017/07/hack-iso-usb-isohybrid.html