Moved from cronie to systemd timers because they are resilient to system startup times. My backup strategy is to create a borg archive entry every day at a fixed time. With cronie the system needs to be running at the scheduled time, but systemd timer tolates this and runs the service as soons as the system is available.
NixOS comes with systemd, so I've been using it as a first-class part of managing stuff. It's great, especially coming from macOS' launchd.
Which makes it nice to distribute a tool for NixOS so that it can lean into systemd instead of as some bolted-on afterthought.
Makes me wonder what you'd do if you were distributing a lifecycle-heavy tool for Linux users in general since systemd isn't ubiquitous.
I use a systemd timer to run a monthly scrub for my btrfs pool. Kinda cool how you can do increasingly useful things like skip the next scheduled event if the user initiates a scrub, do or don't accumulate tasks if you have a monthly task but the machine was offline for 6 months -- or fold them into a single task, etc.
Have you been defining them directly in your flake.nix file? I too am on nixos but I keep all my configurations in their native format and symlink them with nix, that way I can take and reuse that config on a non nixos system easily.
The problem I have found is that nixos doesn't seem to pickup and run systemd timers and services placed into the ~/.config/systems/user folder and additionally things like WantedBy=default.target have no effect.
So after I restart all my services manually on reboot I agree, systems timers are cool.
Timers can work with arbitrary units (not just a similarly-named service unit) so they can be surprisingly flexible. I have a timer on my servers that starts a backup.target that fires off a full "restic backup","restic prune", "restic forget" backup cycle each morning with randomized start times and notifications. The actual restic-* units are Podman Quadlets so the whole setup runs agnosticaly of what's on the server, just as long as it has Podman and Systemd installed.
I will admit thought, timers are up there in terms of being the clunkiest systemd unit type to use on a regular basis. I get why they're split up into two files and require different start vs enable syntax's, but man sometimes I just want to create a file that runs a script and be done with it.
Never thought I'd see hackers saying INI format looked ugly of all things. It's basic, sure, but that's a good thing for something meant to be easily editable by hand from any editor. Otherwise, it's just key value pairs in named sections, how ugly can it be about that?
There's definitely some weirdness to certain parts of systemd service files, but was a huge improvement over Upstart and the old SysV-style init scripts.
Over all I think Systemd get way to much criticism. You don't have to use all the parts, but if you care to go through the documentation you'll find interesting features such as journald log-shipping and systemd-machined which can manage containers and VMs.
Oh yes, because the well documented clean syntax of sys v init shell scripts was so nice.
If I never recall hacking in ulimit calls in the top of buggy shell scripts for crappy old services that done respect pam_limits it won’t be soon enough.
Since systemd is successfully parsing its INI files, and barks at you when you put weird shit into them, a grammar for them does exist as well.
XML is that wonderful format that gave us vulnerabilities like death by million laughs, up to a certain moment, you could MitM DTDs, and a whole slew of everything-XML stuff back when XML was like AI is today, none of which I miss today.
Oh, and remember times when programmers would argue whether argument order in XML files should be significant or not?
But XML books with their idealized XML future description did give me the same warm fuzzies as some intricate clockwork mechanism to a Victorian geek.
This is very interesting. I'm not sure what I'd use it for yet, but I imagine it could be useful for triggering ad hoc jobs over the network. Maybe have Home Assistant make a network call to kick off a daily back up when I leave the office at the end of a work day.
I believe its original motivation was just speeding up boot times by starting fewer services, even if you'd eventually want the service running. This was achieved in the past with xinetd, but systemd made the approach more popular for the masses.
Btw this is my repo for the backup automation: https://github.com/gchamon/borg-automated-backups
Which makes it nice to distribute a tool for NixOS so that it can lean into systemd instead of as some bolted-on afterthought.
Makes me wonder what you'd do if you were distributing a lifecycle-heavy tool for Linux users in general since systemd isn't ubiquitous.
I use a systemd timer to run a monthly scrub for my btrfs pool. Kinda cool how you can do increasingly useful things like skip the next scheduled event if the user initiates a scrub, do or don't accumulate tasks if you have a monthly task but the machine was offline for 6 months -- or fold them into a single task, etc.
The problem I have found is that nixos doesn't seem to pickup and run systemd timers and services placed into the ~/.config/systems/user folder and additionally things like WantedBy=default.target have no effect.
So after I restart all my services manually on reboot I agree, systems timers are cool.
a) It is way nicer and you get decent validation at build time
b) A LLM can port units over if the need arises; it’s a very light abstraction around systemd syntax
c) I personally don’t see how I would ever move to another distro :)
I will admit thought, timers are up there in terms of being the clunkiest systemd unit type to use on a regular basis. I get why they're split up into two files and require different start vs enable syntax's, but man sometimes I just want to create a file that runs a script and be done with it.
Over all I think Systemd get way to much criticism. You don't have to use all the parts, but if you care to go through the documentation you'll find interesting features such as journald log-shipping and systemd-machined which can manage containers and VMs.
If I never recall hacking in ulimit calls in the top of buggy shell scripts for crappy old services that done respect pam_limits it won’t be soon enough.
Could have been YAML.
Could have been XML.
It would also make it much simpler to make good GUI editors for the files instead of the Notepad approach most unix config files take.
https://www.freedesktop.org/software/systemd/man/latest/syst...
XML is that wonderful format that gave us vulnerabilities like death by million laughs, up to a certain moment, you could MitM DTDs, and a whole slew of everything-XML stuff back when XML was like AI is today, none of which I miss today.
Oh, and remember times when programmers would argue whether argument order in XML files should be significant or not?
But XML books with their idealized XML future description did give me the same warm fuzzies as some intricate clockwork mechanism to a Victorian geek.