This is a shame to read, I've thought of learning Nix for basic devops tasks and avoid tools like Ansible. Is this critique true for Nix in general or just NixOS?
As with anything, "it depends." I think Nix and NixOS is great for personal and hobby stuff, but I cannot in good faith recommend it for anything professional. I personally run my daily driver on NixOS and haven't had any desire to change, but I'd prefer to never have to write an actual line of Nix code again.
> I cannot in good faith recommend it for anything professional.
What separates the professional from the 'personal and hobby stuff': the need for (timely) reliability, and that you want other people to be able to maintain it.
With Nix, because it's so strict, it's more difficult to quickly kludge a solution. If something doesn't work as you expect, it may demand understanding of different parts of the solution stack.
That Nix isn't widely adopted means it's harder to find e.g. StackOverflow answers for problems.
In the blogpost, an example of a problem they had to work around was that fish's configuration expected to work statefully in a way which didn't work well with Nix's Home Manager's declarative nature.
To me, it reads like the author tried the tool, thought it was really neat, and discusses the problems they ran into (& how they fixed them). Once they got a simple setup that solved their needs, the author was enthusiastic to apply the tool to everything they had. -- Not sure I'd describe that as a 'critique'.
That said, I think the experience is demonstrative.
When Nix works, it's amazing, & you'll want to have Nix everywhere.
When something goes wrong with what you're trying to do, Nix can be very challenging, and will typically demand you have a good understanding of what's going on (with what you're trying to do, with Linux, with Nix in order to fix it.
To me it sounds like criticism of someone who jumped on it but did not want to read documentation, then also spent second time of the blog trying to have Nix run on an unprivileged account with small quota.
As for devops task, if it is something that you plan to do and many other users already did than it should be fine. If you are not happy with existing solutions and want things done your way, or it is an uncharted territory then you will need to go through the steep learning curve.
