nixpkgs/nixos/modules/system/activation/switchable-system.nix
nikstur b3c1d8c9ae nixos: add system.switch.enable flag
This flag allows the user to optionally exclude
switch-to-confguration.pl from toplevel.

This is interesting for appliance images where you don't want to re-build
the system. This flag is called `rebuildable` because the standard
interface to do this is `nixos-rebuild` which will not work anymore with
this change.
2023-10-26 17:47:35 +02:00

56 lines
1.8 KiB
Nix

{ config, lib, pkgs, ... }:
let
perlWrapped = pkgs.perl.withPackages (p: with p; [ ConfigIniFiles FileSlurp ]);
in
{
options = {
system.switch.enable = lib.mkOption {
type = lib.types.bool;
default = true;
description = lib.mdDoc ''
Whether to include the capability to switch configurations.
Disabling this makes the system unable to be reconfigured via `nixos-rebuild`.
This is good for image based appliances where updates are handled
outside the image. Reducing features makes the image lighter and
slightly more secure.
'';
};
};
config = lib.mkIf config.system.switch.enable {
system.activatableSystemBuilderCommands = ''
mkdir $out/bin
substitute ${./switch-to-configuration.pl} $out/bin/switch-to-configuration \
--subst-var out \
--subst-var-by toplevel ''${!toplevelVar} \
--subst-var-by coreutils "${pkgs.coreutils}" \
--subst-var-by distroId ${lib.escapeShellArg config.system.nixos.distroId} \
--subst-var-by installBootLoader ${lib.escapeShellArg config.system.build.installBootLoader} \
--subst-var-by localeArchive "${config.i18n.glibcLocales}/lib/locale/locale-archive" \
--subst-var-by perl "${perlWrapped}" \
--subst-var-by shell "${pkgs.bash}/bin/sh" \
--subst-var-by su "${pkgs.shadow.su}/bin/su" \
--subst-var-by systemd "${config.systemd.package}" \
--subst-var-by utillinux "${pkgs.util-linux}" \
;
chmod +x $out/bin/switch-to-configuration
${lib.optionalString (pkgs.stdenv.hostPlatform == pkgs.stdenv.buildPlatform) ''
if ! output=$(${perlWrapped}/bin/perl -c $out/bin/switch-to-configuration 2>&1); then
echo "switch-to-configuration syntax is not valid:"
echo "$output"
exit 1
fi
''}
'';
};
}