this post was submitted on 14 Feb 2024
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I would separate NixOS from other immutable distros. NixOS is really about giving you blank slate and letting you fully configure it.
You do that configuration using a static config language that is able to be far more idempotent than Andible. It’s also able to define packages that are well contained and don’t require dynamic linking setup by manually installing other packages.
Immutable distros, on the other hand, really have no advantage to your setup and will probably feel more restrictive. The main use I see for them is for someone new or lazy that wants to get a working system up and running quickly.
My favorite example of how idempotent NixOS is has to do with the DE. If you've ever looked at switching from gnome to KDE, or the other way around, most distros suggest to just re-install because each DE leaves so much cruft around and it's so hard to remove everything in a safe manner.
With NixOS, you just change one line in your config, and the DE is cleanly swapped.
Or you can add specialisations, which to be fair might require a reboot (system accounts might change during specialisations switch which will confuse the script trying to reload services for the now non-existent user) but it is how I have multiple DEs installed without their applications flooding the other ones, each with their own login manager (SDDM for plasma, gdm for gnome, greetd for sway).
Definitely. That's a great way to run different option together.
I was just using the DE as an example to demonstrate how cleanly NixOS can add and remove packages. The clean removal of packages with lots of configs is something that most distros struggle with.
Well maybe you youself are too new to recognize some of the appeals ;)
One large advantage with silverblue is, that the whole composition of the OS does not take place on the target machine. That means that all the issues that could arise will not take place on the target machine, and can be dealt with beforehand. In the simple case this could mean just enjoying vanilla silverblue without having to think about possibly borking the machine. In an advanced usecase this could mean for example building the os images in a GitLab CI/CD pipeline (with well working tooling that exists already for docker etc), then having automatic tests in the pipeline ensure that everything important works as expected. And only if the tests pass, the image will be added to the repositorie's image registry, where the target machines will fetch it from automatically and rebase to it.
No, I fully understand it. But if you build the whole system where every package is isolated, none of the packages interfere with each other, and every package is tested across a wide array of architectures, you can just as safely put together your ideal OS setup and don't have to deal with being locked into very simple and bare system.
The right place for immutable OSes is if you're using it as a server for container workloads, where you will never customize the base system. Or if you never want to customize your system. Yes, you can customize the system image, but it breaks all the guarantees that the images gives you because the packages themselves are not isolated and by bumping a wrong dependency for a custom packages you can still break the whole system.
Partly yes, but just installing a package without running into conflicts does not yet guarantee a working system. You have to cater for the right configurations too, for example when you think about a corporate setting with all kinds of networking whoes (like shares, vpns and such). I think you could get this to work with Nix somehow, but you want to test these things beforehand, and if you do so using images then you have the thing to ship to machines in your hands already, there's no need to compose the OS and configurations over and over again for every machine.
Another aspect with non-atomic OS composition on the target is that you have to deal with the transient phase from one state to the next. In this phase all kinds of things could happen, for example an update of nvidia drivers would render cuda disfunctional until the next reboot, as the userspace and kernelspace parts do not fit together anymore. With something like any of the fedora atomic variants, transient phases with basically undefined behaviour do not exist, and the time the system is not guaranteed to be in working order gets reduced to just the reboot.
Nix is cool and definetely better than any traditional package manager. But it is not an ultimate solution, to be honest so far it seems to me like it is living in a nieche of enthusiasts that are smart enough to put up with its unique declaration language. And below that niche you have ordinary linux users that may just be happy with silverblue without any modifications, and above that niche you have corporate doing their own images in CI/CD, CoreOS and all that jazz.
Your summary of the language is spot on. I still hope that more distros take inspiration from the declarative config and try to move in the direction, or nix supports a better language in the future. I think that ultimately that's what the average linux user would want. The ability to still customize in a safe manner. Silverblue, and others, are and will remain a great option for the new or indifferent user.
On your point about the transient phase, nix actually does that by default already. It installs everything at a separate path and then flips over in one go. You can even pick the mode, either try to do a live switch as you describe, or on boot. I don't know if I see many benefits to images there.
I am at a second place now that uses NixOS in a corporate setting, and it is much easier than maintaining the CoreOS images, or similar. I've had some many broken builds of CoreOS images because something goes wrong between the custom packages and the base CoreOS images, I would rather just run an Ansible script at this point. Also, you end up using the exact same test suite for NixOS images as for your other images, so the same guarantees end up being met.
Thanks, that clarified things for me. Only thing I really would love to have are atomic updates, but for this I probably could just use BTRFS snapshots.
Already has that. And if you use flakes, you can fully lock down your package versions that way the install is 100% identical on every machine no matter when you run it.