nixpkgs/modules/system/activation/switch-to-configuration.pl

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#! @perl@
use strict;
use warnings;
use File::Basename;
use File::Slurp;
use Cwd 'abs_path';
my $restartListFile = "/run/systemd/restart-list";
my $action = shift @ARGV;
if (!defined $action || ($action ne "switch" && $action ne "boot" && $action ne "test")) {
print STDERR <<EOF;
Usage: $0 [switch|boot|test]
switch: make the configuration the boot default and activate now
boot: make the configuration the boot default
test: activate the configuration, but don\'t make it the boot default
EOF
exit 1;
}
die "This is not a NixOS installation (/etc/NIXOS is missing)!\n" unless -f "/etc/NIXOS";
# Install or update the bootloader.
if ($action eq "switch" || $action eq "boot") {
system("@installBootLoader@ @out@") == 0 or exit 1;
exit 0 if $action eq "boot";
}
# Check if we can activate the new configuration.
my $oldVersion = read_file("/run/current-system/init-interface-version", err_mode => 'quiet') // "";
my $newVersion = read_file("@out@/init-interface-version");
if ($newVersion ne $oldVersion) {
print STDERR <<EOF;
Warning: the new NixOS configuration has an init that is
incompatible with the current configuration. The new configuration
won\'t take effect until you reboot the system.
EOF
exit 100;
}
# Ignore SIGHUP so that we're not killed if we're running on (say)
# virtual console 1 and we restart the "tty1" unit.
$SIG{PIPE} = "IGNORE";
sub getActiveUnits {
# FIXME: use D-Bus or whatever to query this, since parsing the
# output of list-units is likely to break.
my $lines = `@systemd@/bin/systemctl list-units --full`;
my $res = {};
foreach my $line (split '\n', $lines) {
chomp $line;
last if $line eq "";
$line =~ /^(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s/ or next;
next if $1 eq "UNIT";
$res->{$1} = { load => $2, state => $3, substate => $4 };
}
return $res;
}
# Forget about previously failed services.
system("@systemd@/bin/systemctl", "reset-failed");
# Stop all services that no longer exist or have changed in the new
# configuration.
my @unitsToStop;
my $active = getActiveUnits;
while (my ($unit, $state) = each %{$active}) {
my $state = $active->{$unit};
my $baseUnit = $unit;
# Recognise template instances.
$baseUnit = "$1\@.$2" if $unit =~ /^(.*)@[^\.]*\.(.*)$/;
my $curUnitFile = "/etc/systemd/system/$baseUnit";
if (-e $curUnitFile && ($state->{state} eq "active" || $state->{state} eq "activating")) {
my $newUnitFile = "@out@/etc/systemd/system/$baseUnit";
if (! -e $newUnitFile) {
push @unitsToStop, $unit;
} elsif (abs_path($curUnitFile) ne abs_path($newUnitFile)) {
# Record that this unit needs to be started below. We
# write this to a file to ensure that the service gets
# restarted if we're interrupted.
write_file($restartListFile, { append => 1 }, "$unit\n");
push @unitsToStop, $unit;
}
}
}
print STDERR "stopping the following units: ", join(", ", sort(@unitsToStop)), "\n";
system("@systemd@/bin/systemctl", "stop", @unitsToStop)
if scalar @unitsToStop > 0; # FIXME: ignore errors?
# Activate the new configuration (i.e., update /etc, make accounts,
# and so on).
my $res = 0;
print STDERR "activating the configuration...\n";
system("@out@/activate", "@out@") == 0 or $res = 2;
# FIXME: Re-exec systemd if necessary.
# Make systemd reload its units.
system("@systemd@/bin/systemctl", "daemon-reload") == 0 or $res = 3;
# Start all units required by the default target. This should start
# most changed units we stopped above as well as any new dependencies.
print STDERR "starting default target...\n";
system("@systemd@/bin/systemctl", "start", "default.target") == 0 or $res = 4;
# Start changed units we stopped above. This is necessary because
# some may not be dependencies of the default target (i.e., they were
# manually started).
my @stopped = split '\n', read_file($restartListFile, err_mode => 'quiet') // "";
if (scalar @stopped > 0) {
my %unique = map { $_, 1 } @stopped;
my @unique = sort(keys(%unique));
print STDERR "restarting the following units: ", join(", ", @unique), "\n";
system("@systemd@/bin/systemctl", "start", @unique) == 0 or $res = 4;
unlink($restartListFile);
}
# Signal dbus to reload its configuration.
system("@systemd@/bin/systemctl", "reload", "dbus.service");
# Check all the failed services.
$active = getActiveUnits;
my @failed;
while (my ($unit, $state) = each %{$active}) {
push @failed, $unit if $state->{state} eq "failed";
}
if (scalar @failed > 0) {
print STDERR "warning: the following units failed: ", join(", ", sort(@failed)), "\n";
foreach my $unit (@failed) {
print STDERR "\n";
system("COLUMNS=1000 @systemd@/bin/systemctl status --no-pager '$unit' >&2");
}
$res = 4;
}
exit $res;