mirrors/flake-parts
1
0
Fork 0
mirror of https://github.com/hercules-ci/flake-parts.git synced 2024-12-14 11:47:31 +00:00
Code Activity

Document essential module parameters

Browse source
This commit is contained in:
Robert Hensing 2022-05-27 17:41:52 +02:00
parent 19e19dce5a
commit 560ca44596
1 changed files with 52 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

52
README.md
View file

@ -54,3 +54,55 @@ See [the template](./template/default/flake.nix).
# Options Reference
See [flake.parts](https://flake.parts/options.html)
# Top-level module parameters
- `config`, `options`, `lib`, ...: standard module system parameters.
- `getSystem`: function from system string to the `config` of the appropriate `perSystem`.
- `withSystem`: enter the scope of a system. Worked example:
```nix
{ withSystem, ... }:
{
# perSystem = ...;
nixosConfigurations.foo = withSystem "x86_64-linux" (ctx@{ pkgs, ... }:
pkgs.nixos ({ config, lib, packages, pkgs, ... }: {
_module.args.packages = ctx.config.packages;
imports = [ ./nixos-configuration.nix ];
services.nginx.enable = true;
environment.systemPackages = [
packages.hello
];
}));
}
```
# `perSystem` module parameters
- `pkgs`: Defaults to `inputs.nixpkgs.legacyPackages.${system}`. Can be set via `config._module.args.pkgs`.
- `inputs'`: The flake `inputs` parameter, but with `system` pre-selected. Note the last character of the name, `'`, pronounced "prime".
`system` selection is handled by the extensible function [`perInput`](https://flake.parts/options.html#opt-perInput).
- `self'`: The flake `self` parameter, but with `system` pre-selected. This might trigger an infinite recursion (#22), so prefer `config`.
- `system`: The system parameter, describing the architecture and platform of
the host system (where the thing will run).
# Equivalences
- Getting the locally defined `hello` package on/for an `x86_64-linux` host:
- `nix build #hello` (assuming [`systems`](https://flake.parts/options.html#opt-systems) has `x86_64-linux`)
- `config.packages.hello` (if `config` is the `perSystem` module argument)
- `allSystems."x86_64-linux".packages.hello` (assuming [`systems`](https://flake.parts/options.html#opt-systems) has `x86_64-linux`)
- `(getSystem "x86_64-linux").packages.hello)`
- `withSystem "x86_64-linux" ({ config, ... }: config.packages.hello)`
Why so many ways?
1. Flakes counterintuitively handles `system` by enumerating all of them in attribute sets. `flake-parts` does not impose this restriction, but does need to support it.
2. `flake-parts` provides an extensible structure that is richer than the flakes interface alone.