nixos-config VS nixos-infect

I use Nix/NixOS. My system state is a direct result of my config that is declared in a bunch of text files. For example, leaf packages that are installed system-wide are declared here: https://github.com/Atemu/nixos-config/blob/e646c4ec1aac80cfdf7b8c79debcfaee70237018/packages.nix

If it matters, my distro is NixOS and here's the machine's system config: https://github.com/Atemu/nixos-config/blob/95f9bb201ab4c2ab95fb3089909f5951a0646699/configs/HEPHAISTOS/default.nix

If something really goes south, I can have my entire system rebuilt automatically almost to the bit within 5-20min (mostly dependant on Internet speed) because my system is reproducible from just a bunch of text files.

Here's my desktop configuration to give you an idea: https://github.com/Atemu/nixos-config/blob/0e97d9af632852e7440563a9b5976663e61071b7/desktop.nix

If you want to know more: https://nixos.org/ Here's how such a system declaration can look like: My current desktop configuration, packages "installed" system-wide.

If you're looking for a way to restore your system configuration should your drive go kaput, perhaps look into declarative means of configuration instead. With those, your system is defined by a few text files and restoring or duplicating it is trivial. If you want to stay with Arch (great distro), imperative tools like Ansible, Puppet or Chef should work. If you want to try greener pastures, look into NixOS which is what I use. All I need to restore my machine is a few text files like this one (I just clone the git repo).

It only takes https://github.com/Atemu/nixos-config/blob/master/configs/HEPHAISTOS/default.nix#L14 and all these settings are applied: https://github.com/Atemu/nixos-config/blob/af0960a7f7b0d6b9d775015c63a107ede6f63c82/desktop.nix

Here's the list of packages available in all my systems or my desktop configuration to give you an idea.

Set it up once precisely the way you like it, run forever. You only need slight tweaks every now and then to keep up with progress. On how many machines you want with as much shared configuration you want, any time you want. If your NixOS boot drive died, you could have a working NixOS system that's exactly[3] like the old one in a matter of minutes depending on your internet and hardware speed. (Without user data of course.) All you need is one (or a few if you prefer) lean text files that can and should be tracked in a git repo like this on: https://github.com/Atemu/nixos-config

There is one solution I've seen being used to solve this issue.

It is to overwrite the current Linux OS with the one you want. I came across this idea here [0]. I researched and got Alpine Linux running on Hetzner (even they don't support custom images) using a similar method [1].

This seems to be the guide to do the same with Arch Linux [2], I'm not sure though.

Once you do create a successful Arch image on OVH, take a snapshot of the machine before installing anything else, in case you want to start from a fresh Arch image in the future.

[0] https://github.com/elitak/nixos-infect

[1] https://wiki.alpinelinux.org/wiki/Replacing_non-Alpine_Linux...

[2] https://wiki.archlinux.org/title/Install_Arch_Linux_from_exi...

Related:

https://www.reddit.com/r/NixOS/comments/u5gi6e/whats_a_good_...

https://github.com/elitak/nixos-infect

In my experience, the initial learning curve is "way steep" due to incomplete learning resources, the community being split on flakes (I'm not jumping on them yet because I'm sticking with the stable branch), and this one documentation gap in particular.

FWIW, I recently found a VPS offering for $1.41/month (!) @ 1.5GB RAM & 30GB HDD via https://lowendbox.com/, at https://my.racknerd.com/index.php?rp=/store/black-friday-202... (please note I have no idea how reliable it is though!). I managed to deploy NixOS there through nixos-infect (https://github.com/elitak/nixos-infect), and then further configure it with NixOps. That said, using NixOps does currently require a Linux (or Mac, probably) box as the managing one, and some Nix-fu, which is definitely non-trivial. A draft (WIP) writeup on that, if you're interested: https://github.com/akavel/scribbles/blob/main/_drafts/202308...

Those Linode instructions are about installing an OS from an installation ISO from Linode's rescue mode. -- I'd consider that more a 'plus' to Linode that you get to be able to install whatever unsupported Linux on Linode's VMs. But, of course it's not as smooth as the officially supported images.

Sibling comment mentions that NixOS provides ways to build VM images (e.g. https://github.com/nix-community/nixos-generators has a generator specifically for Linode).

Another option is to use nixos-infect, which will replace a Linux distribution with a NixOS distribution. https://github.com/elitak/nixos-infect

> At that point, I feel like all of the repeatability gains are gone. If I want to spin up a fresh server, I have to read a guide and set stuff up by hand?

Just as with ansible, "git pull to deploy". You'd keep a copy of your NixOS configuration.nix somewhere else, and would be able to apply it later.

> it really does let me just get a new VPS and deploy to it very fast

Using a tool you're familiar with to get the job done is going to be faster than learning to use a tool you're unfamiliar with.

I believe much of the use of NixOS is for hobby stuff, and for personal machines. (c.f. "In what environments do you use Nix", Development (1242) vs Home Server (845) vs Production (386) https://discourse.nixos.org/t/2022-nix-survey-results/18983).

for NixOS

Now that you both mention it though, I probably could've skipped the "Boot into the installer" step. I know nixos-infect can install in-place. I havent checked how they do it, but a lighter version that just adds nixos should be pretty easy using ZFS. It probably would've been possible for me to do replace the installer steps with something along the lines of:

You can execute nixos-rebuild on other distros but the NixOS modules and activation scripts expect it to run on NixOS system so it probably will not work (e.g. NixOS would want to control systemd, which would conflict with the distro). And if it did, you would no longer have the other distro but NixOS (see also nixos-infect).