Re:What Is Nix?
by mehrdadn on Wednesday May 20, 2020 @07:12PM
(#23253104)
Great description, thanks. Question: do you know how Nix deals with language package managers (like pip)? If I do sudo pip install (leaving aside the usual debate as to its merits), does that then wreck my Nix install, especially if it happens to contain another version of the same package? And does it instantly make things non-reproducible again (just like the apt-get issue you mentioned)? Or does Nix somehow get around it?
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It's totally possible to introduce mutable, non-reproducible state on a system that uses Nix, even if that system is NixOS. However, you can't do so in your Nix store, which is where all the Nix-installed things live (at least, not without a lot of hackery - Nix tries very hard to make the entire store immutable).
Basically this works out to: anything you install or configure with Nix, is immutable and reproducible. Anything you don't is at your own risk. Unfortunately there are still some "pockets of state" that haven't been solved yet, most notably applications storing state in ~.
For most every language dependency management system, there's a Nix equivalent of some sort that allows you to manage those dependencies without invoking the non-reproducible mutable tooling.
Re:What Is Nix?
by throwaway894345 on Wednesday May 20, 2020 @08:03PM
(#23253475)
Nix doesn't pay any attention to the rest of your system. It keeps everything it needs (including its own Python interpreter) in its own "nix store" directory, at /nix/store. You can crudely think of it as having its own virtualenv for every distinct Python target you use.