I recently switched distros on my server, from Debian to Fedora, to use systemd and keep it in line with my home Arch Linux system (which was not reinstalled since 2010, by the way!) Why is systemd so awesome? Read on to find out.
(I changed the hardware for my home system along the way. And just copied everything over with ``dd``. That’s Linux at its finest.)
The most important thing in systemd is its user friendliness. systemd offers the systemctl tool, which can be used to control all the services. You can see what exactly is going on: what is running, what failed to start, and you can also see why if you ask systemctl status $SERVICE.
Writing services is fun¶
If you want your own services, you just need to write some simple INI files. No need for bash, distro-specific frameworks and whatnot. If I have a functioning service written on Arch, I can just copy the file over to Fedora and blindly enable it — assuming I have the executables installed, it’s guaranteed to work.
And the units are tiny:
fedora$ wc -l /usr/lib/systemd/system/nginx.service 15 /usr/lib/systemd/system/nginx.service debian$ wc -l /etc/init.d/nginx 101 /etc/init.d/nginx
And you can write a bare-minimum systemd daemon in less than that – not so easy with sysvinit (writing everything on one line doesn’t count!)
Managing personal services¶
systemd also features user-specific services. You can run any service as your user. I use this to run KwBot, which was previously under control of supervisord — that’s one less dependency to care about!
Runlevels do not exist¶
systemd does away with the standard convention of runlevels. They are replaced by human-friendly targets. Each unit defines its target: most use multi-user.target. It is much easier to manage.
Units can depend on each other¶
Do you have some units that require the network to be up? Set it to be run after and require network.target and call it a day.
If I want to know what is going on in my system, I can just ask journalctl to show me the most recent messages. I don’t need to read a thousand different log files — most things appear in the journal. Sure, some things aren’t there (yet), but what I can see is very useful.
Did I really change my distro for all that?¶
Yes. I got too annoyed with Debian’s idiocy. Also, DigitalOcean doesn’t really support Debian testing, and I cannot survive with outdated software. I feel much better and, more importantly, safer with Fedora.
(also, the “Veteran Unix Admins” of Devuan are a bunch of idiots.)