Spacewalk has become a dead end. See https://spacewalkproject.github.io/
As far as I'm concerned, in-place upgrading is not something I would seriously trust to work correctly. Red Hat ships with a "leapp" tool to accomplish the task, however, as you may have seen, it is very limited. Perhaps it's OK to upgrade a minimum plain vanilla installation, but then why bother? Why potentially increase the odds of a carefully configured and working system for the sake of upgrading? What is this supposed to fix? Recent releases of RHEL have been fundamentally different, and you also need to look at hardware and other application requirements.
As I recall, it's one of the advantages of the UEK kernel that you can use a newer version without the need to upgrade the OS release version.
That sucks about Spacewalk. Does Oracle have another plan for customers to manage their Linux environments? I'm sure it is just a matter of time before some twit finds and exploits Spacewalk and then my InfoSec Team will shut down my running instance of Spacewalk.
I guess with Oracle Linux 7 support lasting until July 2024 I'll ride out the version 7 for a couple more years. I always prefer clean builds but my application support teams would rather do in-place upgrades. Before Oracle Linux we ran SUSE (SLES) and I was pretty successful upgrading 9 to 10 and 10 to 11 but then systemd came along and had to perform clean installations. I guess time will tell but man, that is not good news.
In case you missed it, there was a recent discussion you may find interesting:
Well, what can you do? Perhaps there are too many cooks and too many solutions competing with another. Someone at Red Hat does perhaps not consider existing knowledge a reasonable investment. There is too much money in the cloud and the gap of interests between vendors and and end-users just keeps growing, unless you are a newbie. Why "selling" a product and convincing customers, when you can simply force it down people's throat? But that's probably all just my own personal observation or imagination.
Two questions: first, there is no supported upgrade path from OL7 to OL8. You will need to reinstall the operating system. Second, we are still working on releasing Spacewalk 2.10 which will have limited support for Oracle Linux 8 clients. We will also be announcing our roadmap for Linux management when we release Spacewalk 2.10.
Recently upgraded my open-source version from Spacewalk 2.9 to Spacewalk 2.10, everything looks fine but only issue I have is "can not kickstart new any version 8 client", which included Oracle/CentOS/RHEL 8.x (don't have SUSE repo set up yet)...
Tested all different versions (8.0 - 8.2) thought all three distributers, new client kickstart will get stuck up "Error: Installation Sources", assume due to the version 8.x changed from /Packages to /BaseOS/Packages and /AppStream/Packages two different locations.
As long as I built those version 8.x client via DVD with minimum configurations ( or clone from template ), they can be included new Spacewalk 2.10 and managed as normal.