nixpkgs/flake.nix
Jade Lovelace e456032add nixos/flake: put nixpkgs in NIX_PATH and system registry for flake configs
Currently there are a bunch of really wacky hacks required to get nixpkgs
path correctly set up under flake configs such that `nix run
nixpkgs#hello` and `nix run -f '<nixpkgs>' hello` hit the nixpkgs that
the system was built with. In particular you have to use specialArgs or
an anonymous module, and everyone has to include this hack in their
own configs.

We can do this for users automatically.

I have tested these manually with a basic config; I don't know if it is
even possible to write a nixos test for it since you can't really get a
string-with-context to yourself unless you are in a flake context.
2024-02-03 20:44:38 -08:00

108 lines
4.3 KiB
Nix

# Experimental flake interface to Nixpkgs.
# See https://github.com/NixOS/rfcs/pull/49 for details.
{
description = "A collection of packages for the Nix package manager";
outputs = { self }:
let
jobs = import ./pkgs/top-level/release.nix {
nixpkgs = self;
};
libVersionInfoOverlay = import ./lib/flake-version-info.nix self;
lib = (import ./lib).extend libVersionInfoOverlay;
forAllSystems = lib.genAttrs lib.systems.flakeExposed;
in
{
lib = lib.extend (final: prev: {
nixos = import ./nixos/lib { lib = final; };
nixosSystem = args:
import ./nixos/lib/eval-config.nix (
{
lib = final;
# Allow system to be set modularly in nixpkgs.system.
# We set it to null, to remove the "legacy" entrypoint's
# non-hermetic default.
system = null;
modules = args.modules ++ [
# This module is injected here since it exposes the nixpkgs self-path in as
# constrained of contexts as possible to avoid more things depending on it and
# introducing unnecessary potential fragility to changes in flakes itself.
#
# See: failed attempt to make pkgs.path not copy when using flakes:
# https://github.com/NixOS/nixpkgs/pull/153594#issuecomment-1023287913
({ config, pkgs, lib, ... }: {
config.nixpkgs.flake.source = self.outPath;
})
];
} // builtins.removeAttrs args [ "modules" ]
);
});
checks.x86_64-linux = {
tarball = jobs.tarball;
# Test that ensures that the nixosSystem function can accept a lib argument
# Note: prefer not to extend or modify `lib`, especially if you want to share reusable modules
# alternatives include: `import` a file, or put a custom library in an option or in `_module.args.<libname>`
nixosSystemAcceptsLib = (self.lib.nixosSystem {
lib = self.lib.extend (final: prev: {
ifThisFunctionIsMissingTheTestFails = final.id;
});
modules = [
./nixos/modules/profiles/minimal.nix
({ lib, ... }: lib.ifThisFunctionIsMissingTheTestFails {
# Define a minimal config without eval warnings
nixpkgs.hostPlatform = "x86_64-linux";
boot.loader.grub.enable = false;
fileSystems."/".device = "nodev";
# See https://search.nixos.org/options?show=system.stateVersion&query=stateversion
system.stateVersion = lib.versions.majorMinor lib.version; # DON'T do this in real configs!
})
];
}).config.system.build.toplevel;
};
htmlDocs = {
nixpkgsManual = jobs.manual;
nixosManual = (import ./nixos/release-small.nix {
nixpkgs = self;
}).nixos.manual.x86_64-linux;
};
# The "legacy" in `legacyPackages` doesn't imply that the packages exposed
# through this attribute are "legacy" packages. Instead, `legacyPackages`
# is used here as a substitute attribute name for `packages`. The problem
# with `packages` is that it makes operations like `nix flake show
# nixpkgs` unusably slow due to the sheer number of packages the Nix CLI
# needs to evaluate. But when the Nix CLI sees a `legacyPackages`
# attribute it displays `omitted` instead of evaluating all packages,
# which keeps `nix flake show` on Nixpkgs reasonably fast, though less
# information rich.
legacyPackages = forAllSystems (system:
(import ./. { inherit system; }).extend (final: prev: {
lib = prev.lib.extend libVersionInfoOverlay;
})
);
nixosModules = {
notDetected = ./nixos/modules/installer/scan/not-detected.nix;
/*
Make the `nixpkgs.*` configuration read-only. Guarantees that `pkgs`
is the way you initialize it.
Example:
{
imports = [ nixpkgs.nixosModules.readOnlyPkgs ];
nixpkgs.pkgs = nixpkgs.legacyPackages.x86_64-linux;
}
*/
readOnlyPkgs = ./nixos/modules/misc/nixpkgs/read-only.nix;
};
};
}