nixpkgs/nixos/modules/system/activation/activation-script.nix
2024-07-16 20:42:06 +02:00

287 lines
8.8 KiB
Nix

# generate the script used to activate the configuration.
{ config, lib, pkgs, ... }:
with lib;
let
addAttributeName = mapAttrs (a: v: v // {
text = ''
#### Activation script snippet ${a}:
_localstatus=0
${v.text}
if (( _localstatus > 0 )); then
printf "Activation script snippet '%s' failed (%s)\n" "${a}" "$_localstatus"
fi
'';
});
systemActivationScript = set: onlyDry: let
set' = mapAttrs (_: v: if isString v then (noDepEntry v) // { supportsDryActivation = false; } else v) set;
withHeadlines = addAttributeName set';
# When building a dry activation script, this replaces all activation scripts
# that do not support dry mode with a comment that does nothing. Filtering these
# activation scripts out so they don't get generated into the dry activation script
# does not work because when an activation script that supports dry mode depends on
# an activation script that does not, the dependency cannot be resolved and the eval
# fails.
withDrySnippets = mapAttrs (a: v: if onlyDry && !v.supportsDryActivation then v // {
text = "#### Activation script snippet ${a} does not support dry activation.";
} else v) withHeadlines;
in
''
#!${pkgs.runtimeShell}
source ${./lib/lib.sh}
systemConfig='@out@'
export PATH=/empty
for i in ${toString path}; do
PATH=$PATH:$i/bin:$i/sbin
done
_status=0
trap "_status=1 _localstatus=\$?" ERR
# Ensure a consistent umask.
umask 0022
${textClosureMap id (withDrySnippets) (attrNames withDrySnippets)}
'' + optionalString (!onlyDry) ''
# Make this configuration the current configuration.
# The readlink is there to ensure that when $systemConfig = /system
# (which is a symlink to the store), /run/current-system is still
# used as a garbage collection root.
ln -sfn "$(readlink -f "$systemConfig")" /run/current-system
exit $_status
'';
path = with pkgs; map getBin
[ coreutils
gnugrep
findutils
getent
stdenv.cc.libc # nscd in update-users-groups.pl
shadow
nettools # needed for hostname
util-linux # needed for mount and mountpoint
];
scriptType = withDry: with types;
let scriptOptions =
{ deps = mkOption
{ type = types.listOf types.str;
default = [ ];
description = "List of dependencies. The script will run after these.";
};
text = mkOption
{ type = types.lines;
description = "The content of the script.";
};
} // optionalAttrs withDry {
supportsDryActivation = mkOption
{ type = types.bool;
default = false;
description = ''
Whether this activation script supports being dry-activated.
These activation scripts will also be executed on dry-activate
activations with the environment variable
`NIXOS_ACTION` being set to `dry-activate`.
it's important that these activation scripts don't
modify anything about the system when the variable is set.
'';
};
};
in either str (submodule { options = scriptOptions; });
in
{
###### interface
options = {
system.activationScripts = mkOption {
default = {};
example = literalExpression ''
{ stdio.text =
'''
# Needed by some programs.
ln -sfn /proc/self/fd /dev/fd
ln -sfn /proc/self/fd/0 /dev/stdin
ln -sfn /proc/self/fd/1 /dev/stdout
ln -sfn /proc/self/fd/2 /dev/stderr
''';
}
'';
description = ''
A set of shell script fragments that are executed when a NixOS
system configuration is activated. Examples are updating
/etc, creating accounts, and so on. Since these are executed
every time you boot the system or run
{command}`nixos-rebuild`, it's important that they are
idempotent and fast.
'';
type = types.attrsOf (scriptType true);
apply = set: set // {
script = systemActivationScript set false;
};
};
system.dryActivationScript = mkOption {
description = "The shell script that is to be run when dry-activating a system.";
readOnly = true;
internal = true;
default = systemActivationScript (removeAttrs config.system.activationScripts [ "script" ]) true;
defaultText = literalMD "generated activation script";
};
system.userActivationScripts = mkOption {
default = {};
example = literalExpression ''
{ plasmaSetup = {
text = '''
''${pkgs.libsForQt5.kservice}/bin/kbuildsycoca5"
''';
deps = [];
};
}
'';
description = ''
A set of shell script fragments that are executed by a systemd user
service when a NixOS system configuration is activated. Examples are
rebuilding the .desktop file cache for showing applications in the menu.
Since these are executed every time you run
{command}`nixos-rebuild`, it's important that they are
idempotent and fast.
'';
type = with types; attrsOf (scriptType false);
apply = set: {
script = ''
unset PATH
for i in ${toString path}; do
PATH=$PATH:$i/bin:$i/sbin
done
_status=0
trap "_status=1 _localstatus=\$?" ERR
${
let
set' = mapAttrs (n: v: if isString v then noDepEntry v else v) set;
withHeadlines = addAttributeName set';
in textClosureMap id (withHeadlines) (attrNames withHeadlines)
}
exit $_status
'';
};
};
environment.usrbinenv = mkOption {
default = "${pkgs.coreutils}/bin/env";
defaultText = literalExpression ''"''${pkgs.coreutils}/bin/env"'';
example = literalExpression ''"''${pkgs.busybox}/bin/env"'';
type = types.nullOr types.path;
visible = false;
description = ''
The env(1) executable that is linked system-wide to
`/usr/bin/env`.
'';
};
system.build.installBootLoader = mkOption {
internal = true;
# "; true" => make the `$out` argument from switch-to-configuration.pl
# go to `true` instead of `echo`, hiding the useless path
# from the log.
default = "echo 'Warning: do not know how to make this configuration bootable; please enable a boot loader.' 1>&2; true";
description = ''
A program that writes a bootloader installation script to the path passed in the first command line argument.
See `nixos/modules/system/activation/switch-to-configuration.pl`.
'';
type = types.unique {
message = ''
Only one bootloader can be enabled at a time. This requirement has not
been checked until NixOS 22.05. Earlier versions defaulted to the last
definition. Change your configuration to enable only one bootloader.
'';
} (types.either types.str types.package);
};
};
###### implementation
config = {
system.activationScripts.stdio = ""; # obsolete
system.activationScripts.var = ""; # obsolete
systemd.tmpfiles.rules = [
# Prevent the current configuration from being garbage-collected.
"d /nix/var/nix/gcroots -"
"L+ /nix/var/nix/gcroots/current-system - - - - /run/current-system"
"D /var/empty 0555 root root -"
"h /var/empty - - - - +i"
];
system.activationScripts.usrbinenv = if config.environment.usrbinenv != null
then ''
mkdir -p /usr/bin
chmod 0755 /usr/bin
ln -sfn ${config.environment.usrbinenv} /usr/bin/.env.tmp
mv /usr/bin/.env.tmp /usr/bin/env # atomically replace /usr/bin/env
''
else ''
rm -f /usr/bin/env
rmdir --ignore-fail-on-non-empty /usr/bin /usr
'';
system.activationScripts.specialfs =
''
specialMount() {
local device="$1"
local mountPoint="$2"
local options="$3"
local fsType="$4"
if mountpoint -q "$mountPoint"; then
local options="remount,$options"
else
mkdir -p "$mountPoint"
chmod 0755 "$mountPoint"
fi
mount -t "$fsType" -o "$options" "$device" "$mountPoint"
}
source ${config.system.build.earlyMountScript}
'';
systemd.user = {
services.nixos-activation = {
description = "Run user-specific NixOS activation";
script = config.system.userActivationScripts.script;
unitConfig.ConditionUser = "!@system";
serviceConfig.Type = "oneshot";
wantedBy = [ "default.target" ];
};
};
};
}