Create custom rocky ISO

Hello rocky community,

I would like to make a personal project to test and learn more about customizing linux distro.
I’d like to make a network firewall/router out of rocky linux. I think it will be fun to experiment.

I’d like some advices on how to customize iso and where to start.

My first idea is to unpack rocky iso, create a kickstart and automate at maximum installation. Then put the kickstart directly in the iso make it boot directly with the kickstart. Is it a good idea or do you see any smarter/simpler way to do this ? Let me know :slight_smile:

Thanks for reading

You can use mkksiso to add a kickstart to a given ISO. There’s no need to unpack it.

dnf install lorax -y
mkksiso /path/to/kickstart /path/to/iso /path/to/output.iso

Oh that’s a nice tool, thanks ! i’m used to the debian’s preseed way where you have to unpack and repack to automate installation

For me that fails with an error.

Command I executed:
mkksiso kick Rocky-9.1-x86_64-minimal.iso Rocky-9.1-x86_64-minimal-LG.iso


libisofs: WARNING : Found hidden El-Torito image. Its size could not be figured out, so image modify or boot image patching may lead to bad results.
xorriso : NOTE : Detected El-Torito boot information which currently is set to be discarded
xorriso : SORRY : Cannot enable EL Torito boot image #1 because it is not a data file in the ISO filesystem

I therefore would like to ask the makers of that ISO file to make it mkksiso-friendly. Thanks.

Despite the messages from the command, it is not an error. They are warnings. The ISO does get made with the kickstart, but is only UEFI bootable as a result. To avoid this so it’s bootable on both MBR and UEFI, you will need to obtain an updated ISO.

The latest ISO’s are here: Index of /pub/rocky/9/isos/x86_64/