NIX_PATH can get out of date

[chvp]

If the system is updated while a user is logged in, their NIX_PATH variable can get out of date when using the saneFlakeDefaults. This can get noticeable if one updates through a full rebuild on a graphical system, resulting in graphical applications accessed through a nix-shell refusing to start. I solved this this way in my flake: https://github.com/chvp/nixos-config/blob/f3a7f168d5bc46fb5d9c7946b59bed327cf1e609/flake.nix#L28-L33 (the .version-suffix file is also useful, nix-direnv relies on it to do its caching).

[gytis-ivaskevicius]

This is a known issue (at least to me) that NIX_PATH fails to update due to other applications not re-sourcing /etc/set-environment file.
this was my fix: https://github.com/gytis-ivaskevicius/nixfiles/blob/master/home-manager/sway.nix#L79

I actually never considered that it ever worked differently since I initially moved to flakes quite early on and never paid that much attention to it, but I believe I can fix it by reverting some of the NIX_PATH logic.

Keep in mind that the issue will persist when adding/removing flakes, but I will definitely make sure that at least some of the flakes will use a static path instead. You can expect a fix today/tomorrow

[gytis-ivaskevicius]

Also, I created a discussion here: https://discourse.nixos.org/t/i-feel-like-nix-path-creates-more-issues-than-it-fixes/12110, I wonder what are other peeps thoughts on this.

[gytis-ivaskevicius]

As commit notes - removed custom NIX_PATH implementation. Does not seem to be too relevant in the new world of flakes

[chvp]

Sure, I'll do it myself again. The solution posted on discourse is nice, it saves a slow derivation from what I used to do.

[chvp]

For anyone stumbling upon this issue later: this is how I ended up solving it in my flake: https://github.com/chvp/nixos-config/blob/17a4f0a7a104ad263f5e361f57e18c6a5009eca5/flake.nix#L22-L25