When inlining a module with a problematic declaration, you usually get
get a not-so helpful error like this:
$ cat flake.nix
{
description = "A very basic flake";
inputs.nixpkgs.url = path:../.;
outputs = { self, nixpkgs }: {
nixosConfigurations.foo = nixpkgs.lib.nixosSystem {
system = "x86_64-linux";
modules = [
({ lib, ... }: { services.wrong = 2; })
{ services.nginx.enable = true; }
];
};
};
}
$ nixos-rebuild build --flake .#foo -L
error: The option `services.wrong' does not exist. Definition values:
- In `<unknown-file>': 2
While it's certainly possible to guess where this comes from, this is
IMHO fairly confusing for beginners (and kinda reminds me of the
infamous "infinite recursion at undefined position"-error).
The module-system determines the position of a declaration using the
`_file`-key: this is either `toString path` if `path` is e.g. a value
from `imports = [ ./foo.nix ]` or the file used as `NIXOS_CONFIG` in
`<nixpkgs/nixos>`.
However such a mechanism doesn't exist (yet) for inlined flake modules,
so I tried to implement this in a fairly basic way:
* For non-path declarations, the position of `modules` inside the
`flake.nix` which declares these modules is determined by doing
`unsafeGetAttrPos` on the `modules`-argument of `lib.nixosSystem`.
So the `flake.nix` from above would now raise the following
error-message:
$ nixos-rebuild build --flake .#foo -L
error: The option `services.wrong' does not exist. Definition values:
- In `/nix/store/4vi3nhqjyma73ygs4f93q38qjkhkaxw8-source/flake.nix': 2
Co-authored-by: Cole Helbling <cole.e.helbling@outlook.com>
Co-authored-by: Silvan Mosberger <github@infinisil.com>
Co-authored-by: Robert Hensing <robert@roberthensing.nl>
Their keys are now not used directly. Instead, we go the standard route of mapping to the
UUID in order to apply the rename procedure. This makes sure the manual override always does
the correct thing, and also gives us more consistency overall.
