zlacker

>>todsac+(OP)
I would like a comparison with runit, which is a very minimal but almost full-fledged init system. I see many similarities: control directories, no declarative dependencies, a similar set of scripts, the same approach to logging. The page mentions runit in passing, and even suggests using the chpst utility from it.

One contrasting feature is parametrized services: several similar processes (like agetty) can be controlled by one service directory; I find it neat.

Another difference is the ability to initiate reboot or shutdown as an action of the same binary (nitroctl).

Also, it's a single binary; runit has several.

>>nine_k+0k
Last year I decommed our last couple of servers that ran processes configured using runit. It was a sad day. I first learned to write runit services probably about 15 years ago and it was very cool and very understandable and I kind of just thought that's how services worked on linux.

Then I left Linux for about 5 years and, by the time I got back, Systemd had taken over. I heard a few bad things about it, but eventually learned to recognise that so many of those arguments were in such bad faith that I don't even know what the real ones are any more. Currently I run a couple of services on Pi Zeros streaming camera and temperature data from the vivarium of our bearded dragon, and it was so very easy to set them up using systemd. And I could use it to run emacsd on my main OpenSuse desktop. And a google-drive Fuse solution on my work laptop. "having something standard is good, actually", I guess.

>>J_McQu+nX
The backlash against systemd was twofold. On one hand, when released and thrust upon distros via Gnome, it was quite rough around the edges, which caused both real problems and just understandable irritation. Fifteen years after, the kinks are ironed out, but it was sort of a long time. (Btrfs, released at about the same time, took even longer to stop being imprudent to use in production.)

On the other hand, systemd replaces Unix (sort of like Hurd, but differently). It grabs system init, logging, authentication, DNS, session management, cron, daemon monitoring, socket activation, running containers, etc. In an ideal Red Hat world, I suppose, a bare-metal box should contain a kernel, systemd, podman, IP tools, and maybe sshd and busybox. This is a very anti-Unix, mainframe-like approach, but for a big consulting firm, like Red Hat / IBM, it is very attractive.

>>nine_k+Ha1
All this lather about doing it the UNIX way, whilst neglecting to point out that the old tooling was far worse. "Do one thing well" implies it was done well to begin with.

DNS: Can you from memory recite how name lookups work on Linux? Ever had t otrack down problems with non-standard setups? `resolvectl` is not perfect, but it does let you control all of this stuff in one place, and with a nice, orderly view of what does what.

Init system: ever written the old sysV ones from scratch? Sure they're just shell script, but did you remember to make yours re-entrant? What about forking or master-slave processes? Hope you got your pid checking code just right...

Containers: Docker is quite robust nowadays but it's not like it follows the 'UNIX philosophy' either. And systemd/nspawn at least lets you do namespacing and cgroups reasonably well and in a straightforward way...

Mounts, etc.: let's not get into fstab and its idiosyncrasies.

Logging: let's hope you set up logrotate properly or you're in for a surprise.

And on it goes.

Systemd is not perfect. But what it replaces was god-awful and far worse.

>>mickey+ne1
> DNS: Can you from memory recite how name lookups work on Linux

Yes, I can, and I use systemd only because it's the default on debian, I have no reason to try devuan yet.

> ever written the old sysV ones from scratch?

Many, many times, and I was only an enthusiast/user, not a sysadmin.

> did you remember to make yours re-entrant?

Dealing with PID files was only mildly annoying. Init scripts were very boilerplate-y, so I wouldn't forget anything after my copy-paste-edit-delete unnecessary parts cycle. In a single afternoon, one could bash out an CLI init-script generator that uses jinja2 templates and interactively asking <10 questions about the service.

> Systemd is not perfect. But what it replaces was god-awful and far worse.

Init systems shouldn't have anything to do with managing container lifecycles beyond managing the container-runner service using the usual unix interface (signals). Call me a purist, but system services shouldn't be containerized.

An init system shouldn't be managing DNS or logging either, those should be standalone components. If they are problematic, there should be composable, domain-specific tools that solve them, instead of smooshing everything into systemd.

SystemD wasn't the only possible way to solve those logging, DNS, or security policy problems, and I'm glad other PID 1 projects that focus on being init systems are thriving.