Use nix file excluded from git?

1

i have a system flake project checked in git.
if i have files not staged in git, it will complain it can’t find them until i do.
now my question is: can i circumvent that restriction?

the use-case for this i thought up is, having a nix file containing enable toggles excluded from git. as such, potentially git bisect operations could be sped up a little by temporarily disabling some features the user deems not relevant to the bisect.

it feels like i’m trying stuff you’re not supposed to want so far :see_no_evil:, and i kinda had trouble finding documentation on potential ways to get around this.

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2

You can have a second flake as input that is not a git repo, and have that repo provide a module which flips those switches.

Awkward whenever you need to change them, though.

Alternatively, you can explicitly use the path: prefix to your flake URL to make your git repo be treated as if it was not a git repo.

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3

I’m not entirely sure what you’re looking for, but maybe you could benefit from some source filtering (using lib.fileset): Working with local files — nix.dev documentation

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4

Furthermore, with stable Nix and lib.fileset, it’s possible to import only Git-tracked files into the store, but also add extra files using

lib.fileset.unions [
  # Include all git-tracked files
  (lib.fileset.gitTracked ./.)
  # Plus another one
  ./extra-file
]
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5

@Infinisil i feel i’m sorta missing context on usage here. where might one perhaps invoke this in a basic system flake?
i see your blog post mention mkDerivation, so i imagine that’s about the level this would function at, but iiuc that appears somewhat abstracted away by the nixpkgs.lib.nixosSystem commonly used to do system flakes.

6

Ah yeah you didn’t mention the context, so I wasn’t sure if it would help. lib.fileset is good for filtering local sources of derivations. So indeed, because that doesn’t exist for a NixOS system, it’s not generally useful there.

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7

There’s an open PR to nix to allow for disabling this restriction: Add option to include untracked files in git and mercurial fetchers by jfroche · Pull Request #9352 · NixOS/nix · GitHub

You could build nix yourself with this patch included.
Be aware though, you might end up accidentally importing big files into your store (like if you have a .qcow2 image from a VM run lingering around in your source dir).

8

hm, looks like the mentioned open PR does not pertain to files in .gitignore, unfortunately. :frowning:
it looks like @TLATER’s advice seems to help. i’ll try and figure out how to use that using relative file paths as well.

9

i achieved this now by reading environment variable PWD, requiring impure evaluation.

10

You could just use path-type…

11

this default approach unfortunately fails for files not staged in git, so it looks like you’d need to either use workarounds or trick nix into not considering it a git repo somehow

12

Yes, the path type.

nix build path:. should do…

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