Minimal code to build Ubuntu Focal bottable ISO with installed cloud-init.
Modify files/packages_install.sh for additional packages installed into iso image
Create isogen docker image
build_iso_gen.sh
Modify cloud-init config files in "data" for actions after boot system from iso image
build_ephemeral_iso.sh
Get ephemeral.iso from "data"
Default hostname - "ubuntu-live" You should set different name via cloud-init to clarify boot process.
If cloud-init fails for some reasons you see prompt "ubuntu-live", else you see hostname.
User to debug
devusr:r00tme
Can be changed, removed via /files/packages_install.sh