9f9723b179
Take two of #40708 (4fe2898608).
That PR attempted to bidirectionally default `config.nixpkgs.system` and
`config.nixpkgs.localSystem.system` to each be updated by the other. But
this is not possible with the way the module system works. Divergence in
certain cases in inevitable.
This PR is more conservative and just has `system` default `localSystem`
and `localSystem` make the final call as-is. This solves a number of
issues.
- `localSystem` completely overrides `system`, just like with nixpkgs
proper. There is no need to specify `localSystem.system` to clobber the
old system.
- `config.nixpkgs.localSystem` is exactly what is passed to nixpkgs. No
spooky steps.
- `config.nixpkgs.localSystem` is elaborated just as nixpkgs would so
that all attributes are available, not just the ones the user
specified.
The remaining issue is just that `config.nixpkgs.system` doesn't update
based on `config.nixpkgs.localSystem.system`. It should never be
referred to lest it is a bogus stale value because
`config.nixpkgs.localSystem` overwrites it.
Fixes #46320
67 lines
2.3 KiB
Nix
67 lines
2.3 KiB
Nix
# From an end-user configuration file (`configuration.nix'), build a NixOS
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# configuration object (`config') from which we can retrieve option
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# values.
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# !!! Please think twice before adding to this argument list!
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# Ideally eval-config.nix would be an extremely thin wrapper
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# around lib.evalModules, so that modular systems that have nixos configs
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# as subcomponents (e.g. the container feature, or nixops if network
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# expressions are ever made modular at the top level) can just use
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# types.submodule instead of using eval-config.nix
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{ # !!! system can be set modularly, would be nice to remove
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system ? builtins.currentSystem
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, # !!! is this argument needed any more? The pkgs argument can
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# be set modularly anyway.
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pkgs ? null
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, # !!! what do we gain by making this configurable?
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baseModules ? import ../modules/module-list.nix
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, # !!! See comment about args in lib/modules.nix
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extraArgs ? {}
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, # !!! See comment about args in lib/modules.nix
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specialArgs ? {}
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, modules
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, # !!! See comment about check in lib/modules.nix
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check ? true
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, prefix ? []
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, lib ? import ../../lib
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}:
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let extraArgs_ = extraArgs; pkgs_ = pkgs;
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extraModules = let e = builtins.getEnv "NIXOS_EXTRA_MODULE_PATH";
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in if e == "" then [] else [(import (builtins.toPath e))];
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in
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let
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pkgsModule = rec {
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_file = ./eval-config.nix;
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key = _file;
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config = {
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# Explicit `nixpkgs.system` or `nixpkgs.localSystem` should override
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# this. Since the latter defaults to the former, the former should
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# default to the argument. That way this new default could propagate all
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# they way through, but has the last priority behind everything else.
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nixpkgs.system = lib.mkDefault system;
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_module.args.pkgs = lib.mkIf (pkgs_ != null) (lib.mkForce pkgs_);
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};
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};
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in rec {
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# Merge the option definitions in all modules, forming the full
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# system configuration.
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inherit (lib.evalModules {
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inherit prefix check;
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modules = modules ++ extraModules ++ baseModules ++ [ pkgsModule ];
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args = extraArgs;
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specialArgs = { modulesPath = ../modules; } // specialArgs;
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}) config options;
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# These are the extra arguments passed to every module. In
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# particular, Nixpkgs is passed through the "pkgs" argument.
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extraArgs = extraArgs_ // {
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inherit modules baseModules;
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};
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inherit (config._module.args) pkgs;
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}
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