As for Linux from Scratch - This is something that's been on my radar, but without the part I'm truly interested in (learning more about SysV) then I'm less inclined to bother. I don't buy the reason of Gnome/KDE - isn't LfS all about the basics of the distro than building a fully fledged system? If it's the foundation for the other courses, but it still feels weak that it's so guided by a future GUI requirement for systemd when it's talking about building web servers and the like in a 500Mb or less as the motivation.
All the compliants I see tend to be philisophical criticism of systemd being "not unixy" or "monolithic".
But there's a reason it's being adopted: it does it's job well. It's a pleasure being able to manage timers, socket activations, sandboxing, and resource slices, all of which suck to configure on script based init systems.
People complain in website comment sections how "bloated" systemd is, while typing into reddit webpage that loads megabytes of JS crap.
Meanwhile a default systemd build with libraries is about 1.8MB. That's peanuts.
Systemd is leaps and bounds in front of other init systems, with robust tooling and documentation, and despite misconceptions it actually quite modular, with almost all features gated with options. It gives a consistent interface for linux across distributions, and provides a familar predictible tools for administators.
But it lacks any consistency. It's not a cohesive project with a vision, it's a collection of tools without any overarching idea. This is reflected in its documentation, it's an OK reference manual, but go on and try to build a full picture of system startup.
To give you concrete examples:
1. Systemd has mount units, that you would expect to behave like regular units but for mounts. Except that they don't. You can specify the service retry/restart policy for regular units, including start/stop timeouts, but not for mounts.
2. Except that you can, but only if you use the /etc/fstab compat.
3. Except that you can not, if systemd thinks that your mounts are "local". How does it determine if mounts are local? By checking its mount device.
4. Systemd has separate behaviors for network and local filesystems.
5. One fun example of above, there's a unit that fires up after each system update. It inserts itself _before_ the network startup. Except that in my case, the /dev/sda is actually an iSCSI device and so it's remote. So systemd deadlocks, but only after a system update. FUN!!!
6. How does systemd recognize network filesystems? Why, it has a pre-configured list of them: https://github.com/systemd/systemd/blob/4c6afaab193fcdcb1f5a... Yes, you read it correctly. A low-level mount code has special case for sshfs, that it detects by string-matching.
7. But you can override it, right? Nope. This list is complete and authoritative. Nobody would ever need fuse.s3fs . And if you do, see figure 1.
I can go on for a looooong time.
The iSCSI loop issue: https://github.com/systemd/systemd/issues/34164 It keeps popping up again and again and is summarily ignored.
The remote FS detection also came up multiple times, and the maintainers don't care.
I'm not sure that's fair. I think better proof of this would be a rejected PR rather than a neglected bug report.
This is Linux, after all. Problems found with specific hardware are almost always solved by people with that hardware, not the maintainers, who are usually busy with the 99%.
Lennart refused to make all the /etc/fstab options available in regular mount units. And yes, there was an issue, no I'm too tired to look for it. The wording was pretty much: "Give up, and gtfo, this is not going to happen. Just because."
I'm convinced that systemd can't be fixed by its current team of maintainers. They are just... untidy.
I don't know about you, but if I end up writing low-level code that _needs_ to know whether the mounted file system is "remote", I won't do that by comparing against a hard-coded list of filesystems inside PID0. Or by using wild heuristics ("if it's on a block device, then it's local").
I would put these heuristics in a helper tool that populates the default values for mount units. Then allow users to override them as needed. With a separate inspector tool to flag possible loops.
I recently did a deep dive on my laptop because I was curious about an oddity - the /sys file to change my screen backlight (aside, why /sys and not /dev anyway?) was writable only by root - yet any desktop shell running as my user had no problem reacting to brightness hotkeys. I wondered, how did this privilege escalation work? Where was the policy, and what property of my user account granted it the right to do this?
It turns out the answer is that the desktop shells are firing off a dbus request to org.freedesktop.login1, which is caught by systemd-logind - or elogind in my case, since I do not care for systemd. A login manager seemed an odd place for screen brightness privilege escalation, but hey if it works whatever - it seemed like logind functioned as a sort of miscellaneous grab bag of vaguely console-related stuff. Generally speaking, it consults polkit rules to determine whether a user is allowed to do a thing.
Not screen brightness, though. No polkit rules. Nothing in pkaction. logind was unilaterally consenting to change the brightness on my behalf. And on what grounds? It wasn't documented anywhere so I had to check the source code, where I found a slew of hardcoded criteria that mostly revolve around physical presence at the machine. Want to change screen brightness over ssh? Oh but why would you ever want to do that? Hope you have root access, you weirdo.
I removed elogind. A few odds and ends broke. But nobody tells me what to do with my machine.