Need to create a custom ISO using Ubuntu Base image but I am unable to find one for the same. Can someone please help me find the Ubuntu Base image and also CLI method of creating an ISO from it ?
Step 2: Wrap your system into a .iso image. See https://wiki.debian.org/RepackBootableISO
Step 3: Test, debug, repeat.
Ubuntu Base is an informal project that Canonical engineers use to simplify their various cloud and specialty-hardware projects to provide a uniform Ubuntu experience.
It is not a "real" flavor of Ubuntu. It is not intended to replace the discontinued Netinstall (Minimal) image. It is not designed for easy installation by normal users who can boot PC Hardware from a USB port.
Generally, folks who need to ask "how do I..." about Ubuntu Base should avoid Ubuntu Base; use a more appropriate tool or workflow for your skill level instead.