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.
This commit is contained in:
nikstur 2023-10-14 01:29:05 +02:00
parent f743f021fc
commit b3c1d8c9ae
5 changed files with 98 additions and 39 deletions

View file

@ -1392,6 +1392,7 @@
./system/activation/activatable-system.nix
./system/activation/activation-script.nix
./system/activation/specialisation.nix
./system/activation/switchable-system.nix
./system/activation/bootspec.nix
./system/activation/top-level.nix
./system/boot/binfmt.nix

View file

@ -1,52 +1,16 @@
{ config, lib, pkgs, ... }:
{ options, config, lib, pkgs, ... }:
let
inherit (lib)
mkOption
optionalString
types
;
perlWrapped = pkgs.perl.withPackages (p: with p; [ ConfigIniFiles FileSlurp ]);
systemBuilderArgs = {
activationScript = config.system.activationScripts.script;
dryActivationScript = config.system.dryActivationScript;
};
systemBuilderCommands = ''
echo "$activationScript" > $out/activate
echo "$dryActivationScript" > $out/dry-activate
substituteInPlace $out/activate --subst-var-by out ''${!toplevelVar}
substituteInPlace $out/dry-activate --subst-var-by out ''${!toplevelVar}
chmod u+x $out/activate $out/dry-activate
unset activationScript dryActivationScript
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
${optionalString (pkgs.stdenv.hostPlatform == pkgs.stdenv.buildPlatform) ''
if ! output=$(${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
''}
'';
in
{
options = {
@ -60,6 +24,18 @@ in
do, but for image based systems, this may not be needed or not be desirable.
'';
};
system.activatableSystemBuilderCommands = options.system.systemBuilderCommands // {
description = lib.mdDoc ''
Like `system.systemBuilderCommands`, but only for the commands that are
needed *both* when the system is activatable and when it isn't.
Disclaimer: This option might go away in the future. It might be
superseded by separating switch-to-configuration into a separate script
which will make this option superfluous. See
https://github.com/NixOS/nixpkgs/pull/263462#discussion_r1373104845 for
a discussion.
'';
};
system.build.separateActivationScript = mkOption {
type = types.package;
description = ''
@ -71,7 +47,18 @@ in
};
};
config = {
system.systemBuilderCommands = lib.mkIf config.system.activatable systemBuilderCommands;
system.activatableSystemBuilderCommands = ''
echo "$activationScript" > $out/activate
echo "$dryActivationScript" > $out/dry-activate
substituteInPlace $out/activate --subst-var-by out ''${!toplevelVar}
substituteInPlace $out/dry-activate --subst-var-by out ''${!toplevelVar}
chmod u+x $out/activate $out/dry-activate
unset activationScript dryActivationScript
'';
system.systemBuilderCommands = lib.mkIf
config.system.activatable
config.system.activatableSystemBuilderCommands;
system.systemBuilderArgs = lib.mkIf config.system.activatable
(systemBuilderArgs // {
toplevelVar = "out";
@ -86,7 +73,7 @@ in
})
''
mkdir $out
${systemBuilderCommands}
${config.system.activatableSystemBuilderCommands}
'';
};
}

View file

@ -0,0 +1,55 @@
{ 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
''}
'';
};
}

View file

@ -571,6 +571,7 @@ in {
node-red = handleTest ./node-red.nix {};
nomad = handleTest ./nomad.nix {};
non-default-filesystems = handleTest ./non-default-filesystems.nix {};
non-switchable-system = runTest ./non-switchable-system.nix;
noto-fonts = handleTest ./noto-fonts.nix {};
noto-fonts-cjk-qt-default-weight = handleTest ./noto-fonts-cjk-qt-default-weight.nix {};
novacomd = handleTestOn ["x86_64-linux"] ./novacomd.nix {};

View file

@ -0,0 +1,15 @@
{ lib, ... }:
{
name = "non-switchable-system";
meta.maintainers = with lib.maintainers; [ nikstur ];
nodes.machine = {
system.switch.enable = false;
};
testScript = ''
machine.succeed("test ! -e /run/current-system/bin/switch-to-configuration")
'';
}