Ubuntu 24.04 LTS was released this past April, so one of the things we've been doing since then is building out our install system for 24.04 and then building a number of servers using 24.04, both new servers and servers that used to be build on 20.04 or 22.04. What has been quietly striking about this process is how few changes there have been for us between 20.04, 22.04, and 24.04. Our customization scripts needed only very small changes, and many of the instructions for specific machines could be revised by just searching and replacing either '20.04' or '22.04' with '24.04'.

Some of this lack of changes is illusory, because when I actually look at the differences between our 22.04 and 24.04 postinstall scripting, there are a number of changes, adjustments, and new fixes (and a big change in having to install Python 2 ourselves). Even when we didn't do anything there were decisions to be made, like whether or not we would stick with the Ubuntu 24.04 default of socket activated SSH (our decision so far is to stick with 24.04's default for less divergence from upstream). And there were also some changes to remove obsolete things and restructure how we change things like the system-wide SSH configuration; these aren't forced by the 22.04 to 24.04 change, but building the install setup for a new release is the right time to rethink existing pieces.

However, plenty of this lack of changes is real, and I credit a lot of that to systemd. Systemd has essentially standardized a lot of the init process and in the process, substantially reduced churn in it. For a relevant example, our locally developed systemd units almost never need updating between Ubuntu versions; if it worked in 20.04, it'll still work just as well in 24.04 (including its relationships to various other units). Another chunk of this lack of changes is that the current 20.04+ Ubuntu server installer has maintained a stable configuration file and relatively stable feature set (at least of features that we want to use), resulting in very little needing to be modified in our spin of it as we moved from 20.04 to 22.04 to 24.04. And the experience of going through the server installer has barely changed; if you showed me an installer screen from any of the three releases, I'm not sure I could tell you which it's from.

I generally feel that this is a good thing, at least on servers. A normal Linux server setup and the software that you run on it has broadly reached a place of stability, where there's no particular need to make really visible changes or to break backward compatibility. It's good for us that moving from 20.04 to 22.04 to 24.04 is mostly about getting more recent kernels and more up to date releases of various software packages, and sometimes having bugs fixed so that things like bpftrace work better.

(Whether this is 'welcome maturity' or 'unwelcome statis' is probably somewhat in the eye of the observer. And there are quiet changes afoot behind the scenes, like the change from iptables to nftables.)