c958902d44
which NixOS should be built. This is useful in NixOS network
specifications, because it allows machines in the network to have
different types, e.g.,
{
machine1 =
{ config, pkgs, ... }:
{ nixpkgs.system = "i686-linux";
... other config ...
};
machine2 =
{ config, pkgs, ... }:
{ nixpkgs.system = "x86_64-linux";
... other config ...
};
}
It can also be useful in distributed NixOS tests.
svn path=/nixos/trunk/; revision=24823
75 lines
2.8 KiB
Nix
75 lines
2.8 KiB
Nix
# From an end-user configuration file (`configuration'), 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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{ system ? builtins.currentSystem
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, nixpkgs ? import ./from-env.nix "NIXPKGS" /etc/nixos/nixpkgs
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, services ? ../../services
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, pkgs ? null
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, baseModules ? import ../modules/module-list.nix
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, extraArgs ? {}
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, modules
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}:
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let extraArgs_ = extraArgs; pkgs_ = pkgs; system_ = system; in
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rec {
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# These are the NixOS modules that constitute the system configuration.
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configComponents = modules ++ baseModules;
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# Merge the option definitions in all modules, forming the full
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# system configuration. It's not checked for undeclared options.
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systemModule =
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pkgs.lib.fixMergeModules configComponents extraArgs;
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optionDefinitions = systemModule.config;
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optionDeclarations = systemModule.options;
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inherit (systemModule) 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 pkgs modules baseModules;
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modulesPath = ../modules;
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servicesPath = services;
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pkgs_i686 = import nixpkgs { system = "i686-linux"; };
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};
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# Import Nixpkgs, allowing the NixOS option nixpkgs.config to
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# specify the Nixpkgs configuration (e.g., to set package options
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# such as firefox.enableGeckoMediaPlayer, or to apply global
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# overrides such as changing GCC throughout the system), and the
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# option nixpkgs.system to override the platform type. This is
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# tricky, because we have to prevent an infinite recursion: "pkgs"
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# is passed as an argument to NixOS modules, but the value of "pkgs"
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# depends on config.nixpkgs.config, which we get from the modules.
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# So we call ourselves here with "pkgs" explicitly set to an
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# instance that doesn't depend on nixpkgs.config.
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pkgs =
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if pkgs_ != null
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then pkgs_
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else import nixpkgs (
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let
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system = if nixpkgsOptions.system != "" then nixpkgsOptions.system else system_;
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nixpkgsOptions = (import ./eval-config.nix {
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inherit system nixpkgs services extraArgs modules;
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# For efficiency, leave out most NixOS modules; they don't
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# define nixpkgs.config, so it's pointless to evaluate them.
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baseModules = [ ../modules/misc/nixpkgs.nix ];
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pkgs = import nixpkgs { system = system_; config = {}; };
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}).optionDefinitions.nixpkgs;
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in
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{
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inherit system;
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inherit (nixpkgsOptions) config platform;
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});
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# Optionally check wether all config values have corresponding
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# option declarations.
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config =
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let doCheck = optionDefinitions.environment.checkConfigurationOptions; in
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assert doCheck -> pkgs.lib.checkModule "" systemModule;
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systemModule.config;
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}
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