I too have the nixos vs openbsd decision nibbling at me every time I spin something up.

Here's what helps me decide: I simulate a disaster. Since I'm just me, I do it on paper (empirical ways are best but are also the most expensive, and in a pinch, a thought experiment can illuminate as well. Not always the same things, but light is light.)

Try it -- open a scratch.txt and write about things that would happen, and then the things that would probably happen as a result of that.

The one that often comes up for NixOS is "I lose network connectivity." While NixOS is phenomenal in its ability to roll changes back, the fact that I need a stable Internet connection in order to make any change whatsoever to the current config makes that little piece of CAT-8 a SPOF for any number of unexpected (and intuitively unrelated) matters, making the overall system hard to reason about.

You can mitigate this by hosting your own NixOS channels, which is sort of the equivalent of hosting your own apt-get repo.

But, as you might expect, that's actually a fair amount of extra work. So I don't, especially not on laptops, where space can (still) be limited.

So, every time I do `home-manager switch` I need a viable network connection.

This is especially galling if you (like me) manage most of your apps with Nix' `home-manager`. Think it through; Nix manages (say) your word processor; you want to change the font size in your word processor; you edit your home.nix and hit `home-manager switch`.

But look at what this entails! My apartment building's fibre-optic cabling should never be a depenency on altering the font size in my word processor, but here I am. Ironically, for the sake of convenience.

Now, none of this is to slag on NixOS. As I mentioned above, it's my favourite way to encounter reality. I'm typing this to you on NixOS right now. For me, the pros outweigh the cons. Provided, of course, I have something less brittle than NixOS to back me up, and for me, that means OpenBSD.

I have an OpenBSD instance in the cloud and a break-glass procedure for getting into it. It backs up via another old-school friend, tarsnap. It hosts the git repos that contain my nixos and home-manager configs. If I can talk to it, I can simply zap my NixOS config onto some new edge device and be back up and running in no time.

I also typically have a NUC running OpenBSD present as well, in case that apartment-building fibre gets troublesome (again,) but not at the moment, because my beloved PCEngines device has apparently become unstable under any OS. But when I get that OBSD NUC set (back) up, it will absolutely have a NixOS channel on it, and it will serve as a firewall, a SAN, serving NixOS channels to the edge devices. It will have an actual serial port and a password on a wax-sealed bit of paper in my fireproof safe. Because I think ahead, and that's what I need to get back up and running under the worst circumstances.

I simply can't imagine a non-hardware-failure disaster that could take out an aggressively boring OpenBSD bastion instance. They are just relentless in their persistence.

As I keep saying, NixOS and OpenBSD pair together like honey and mustard. Contrastive but unexpectedly delicious.

Take-home: If you're building infra, try adding some OpenBSD to the mix. It can make the unrecoverable recoverable.