Googling around the internet you will find my ways to do this - including ubuntu's webpage: https://help.ubuntu.com/community/Installation/UnattendedCD
My hope is that this will prevent a lot of the necessary reading and validating. Please feel free to send me any issues or PR requests.
I've tested only on Ubuntu, it will not work on non-debian operating systems due to the install script using apt-get to install udevil. There are simple fixes, if you would like another operating system, you can use mount -o loop (https://askubuntu.com/questions/806820/how-do-i-create-a-completely-unattended-install-of-ubuntu-desktop-16-04-1-lts)
I tried to make it simple enough. You should only really need to edit the configs/ directory. There are two files there:
preseed.cfg
txt.cfg
preseed.cfg is the standard preseed configuration file. I highly suggest taking a look at (https://help.ubuntu.com/lts/installation-guide/example-preseed.txt) for an example preseed.
Any modifications you make to customize your image will occur in preseed.cfg such as controlling timezone, locale, disk partitioning, etc. The preseed.cfg I provide is a very simple config that creates a single user ubuntu with password ubuntu. Enables root login with password root (this is obviously vary dangerous for publically facing systems).
The other file txt.cfg contains the isolinux config file. This points to your custom preseed file, which when copied to the isofiles directory is named custom.seed. You may edit this as you see fit to insert additional bootloader options. (https://help.ubuntu.com/community/LiveCDCustomizationFromScratch#Boot-loader_Configuration)
sudo ./create_custom_iso.sh will run each of the scripts in the scripts directory. You will need to run it as sudo in order to write over read-only data, as well as unmounting and removing the isofiles when finished. Rather than calling the all-in-one script you can call each script individually. Each script will call sudo as necessary.
scripts/install_udevil.sh
scripts/get_ubuntu_1604_server.sh
scripts/mount_ubuntu.sh
scripts/set_autostart_install.sh
scripts/copy_configs_to_isofiles.sh
scripts/create_new_iso.sh
scripts/cleanup.sh
scripts/install_udevil.sh installs udevil - if you are on a non-debian system you can find the correct package (https://manpages.debian.org/jessie/udevil/udevil.1.en.html), or use mount as noted above.
scripts/get_ubuntu_1604_server.sh downloads 16.04.3 ubuntu server.
scripts/mount_ubuntu.sh mounts the iso using udevil to /media/isoname
scripts/set_autostart_install.sh edits isolinux/isolinux.cfg adding a timeout value which I found was necessary to remove the language selection menu prior to reaching the boot menu. Other's have mentioned that passing locale to the bootloader options fixed this problem, which was not the case for me.
scripts/copy_configs_to_isofiles.sh takes the files in configs/ to their correct location in the isofiles directory for when the new iso is generated.
scripts/create_new_iso.sh runs genisoimage to create the new iso!
scripts/cleanup.sh unmounts and removes the data in /media that is added though the udevil command.
at the end you should end up with a bootable iso ubuntu-server-16.04-custom.iso!
If you are interested in creating a pre-configured image, you may be interested in https://github.com/rcgoodfellow/raven-images repo which creates bootable compressed (qcow2) images. For instance if you are using cloud-init or preseeding to generate a custom image for fedora, ubuntu, debian, etc.
https://help.ubuntu.com/lts/installation-guide/s390x/apbs02.html https://askubuntu.com/questions/806820/how-do-i-create-a-completely-unattended-install-of-ubuntu-desktop-16-04-1-lts https://help.ubuntu.com/lts/installation-guide/example-preseed.txt https://help.ubuntu.com/community/InstallCDCustomization https://help.ubuntu.com/community/LiveCDCustomizationFromScratch#Boot-loader_Configuration
