nixpkgs/nixos/modules/system/activation/switch-to-configuration.pl
rnhmjoj 61b7cab481
treewide: use perl.withPackages when possible
Since 03eaa48 added perl.withPackages, there is a canonical way to
create a perl interpreter from a list of libraries, for use in script
shebangs or generic build inputs. This method is declarative (what we
are doing is clear), produces short shebangs[1] and needs not to wrap
existing scripts.

Unfortunately there are a few exceptions that I've found:

  1. Scripts that are calling perl with the -T switch. This makes perl
  ignore PERL5LIB, which is what perl.withPackages is using to inform
  the interpreter of the library paths.

  2. Perl packages that depends on libraries in their own path. This
  is not possible because perl.withPackages works at build time. The
  workaround is to add `-I $out/${perl.libPrefix}` to the shebang.

In all other cases I propose to switch to perl.withPackages.

[1]: https://lwn.net/Articles/779997/
2021-03-31 21:35:37 +02:00

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#! @perl@/bin/perl
use strict;
use warnings;
use File::Basename;
use File::Slurp;
use Net::DBus;
use Sys::Syslog qw(:standard :macros);
use Cwd 'abs_path';
my $out = "@out@";
# FIXME: maybe we should use /proc/1/exe to get the current systemd.
my $curSystemd = abs_path("/run/current-system/sw/bin");
# To be robust against interruption, record what units need to be started etc.
my $startListFile = "/run/systemd/start-list";
my $restartListFile = "/run/systemd/restart-list";
my $reloadListFile = "/run/systemd/reload-list";
my $action = shift @ARGV;
if ("@localeArchive@" ne "") {
$ENV{LOCALE_ARCHIVE} = "@localeArchive@";
}
if (!defined $action || ($action ne "switch" && $action ne "boot" && $action ne "test" && $action ne "dry-activate")) {
print STDERR <<EOF;
Usage: $0 [switch|boot|test]
switch: make the configuration the boot default and activate now
boot: make the configuration the boot default
test: activate the configuration, but don\'t make it the boot default
dry-activate: show what would be done if this configuration were activated
EOF
exit 1;
}
# This is a NixOS installation if it has /etc/NIXOS or a proper
# /etc/os-release.
die "This is not a NixOS installation!\n" unless
-f "/etc/NIXOS" || (read_file("/etc/os-release", err_mode => 'quiet') // "") =~ /ID=nixos/s;
openlog("nixos", "", LOG_USER);
# Install or update the bootloader.
if ($action eq "switch" || $action eq "boot") {
system("@installBootLoader@ $out") == 0 or exit 1;
}
# Just in case the new configuration hangs the system, do a sync now.
system("@coreutils@/bin/sync", "-f", "/nix/store") unless ($ENV{"NIXOS_NO_SYNC"} // "") eq "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 {
my $mgr = Net::DBus->system->get_service("org.freedesktop.systemd1")->get_object("/org/freedesktop/systemd1");
my $units = $mgr->ListUnitsByPatterns([], []);
my $res = {};
for my $item (@$units) {
my ($id, $description, $load_state, $active_state, $sub_state,
$following, $unit_path, $job_id, $job_type, $job_path) = @$item;
next unless $following eq '';
next if $job_id == 0 and $active_state eq 'inactive';
$res->{$id} = { load => $load_state, state => $active_state, substate => $sub_state };
}
return $res;
}
sub parseFstab {
my ($filename) = @_;
my ($fss, $swaps);
foreach my $line (read_file($filename, err_mode => 'quiet')) {
chomp $line;
$line =~ s/^\s*#.*//;
next if $line =~ /^\s*$/;
my @xs = split / /, $line;
if ($xs[2] eq "swap") {
$swaps->{$xs[0]} = { options => $xs[3] // "" };
} else {
$fss->{$xs[1]} = { device => $xs[0], fsType => $xs[2], options => $xs[3] // "" };
}
}
return ($fss, $swaps);
}
sub parseUnit {
my ($filename) = @_;
my $info = {};
parseKeyValues($info, read_file($filename)) if -f $filename;
parseKeyValues($info, read_file("${filename}.d/overrides.conf")) if -f "${filename}.d/overrides.conf";
return $info;
}
sub parseKeyValues {
my $info = shift;
foreach my $line (@_) {
# FIXME: not quite correct.
$line =~ /^([^=]+)=(.*)$/ or next;
$info->{$1} = $2;
}
}
sub boolIsTrue {
my ($s) = @_;
return $s eq "yes" || $s eq "true";
}
sub recordUnit {
my ($fn, $unit) = @_;
write_file($fn, { append => 1 }, "$unit\n") if $action ne "dry-activate";
}
# As a fingerprint for determining whether a unit has changed, we use
# its absolute path. If it has an override file, we append *its*
# absolute path as well.
sub fingerprintUnit {
my ($s) = @_;
return abs_path($s) . (-f "${s}.d/overrides.conf" ? " " . abs_path "${s}.d/overrides.conf" : "");
}
# Figure out what units need to be stopped, started, restarted or reloaded.
my (%unitsToStop, %unitsToSkip, %unitsToStart, %unitsToRestart, %unitsToReload);
my %unitsToFilter; # units not shown
$unitsToStart{$_} = 1 foreach
split('\n', read_file($startListFile, err_mode => 'quiet') // "");
$unitsToRestart{$_} = 1 foreach
split('\n', read_file($restartListFile, err_mode => 'quiet') // "");
$unitsToReload{$_} = 1 foreach
split '\n', read_file($reloadListFile, err_mode => 'quiet') // "";
my $activePrev = getActiveUnits;
while (my ($unit, $state) = each %{$activePrev}) {
my $baseUnit = $unit;
my $prevUnitFile = "/etc/systemd/system/$baseUnit";
my $newUnitFile = "$out/etc/systemd/system/$baseUnit";
# Detect template instances.
if (!-e $prevUnitFile && !-e $newUnitFile && $unit =~ /^(.*)@[^\.]*\.(.*)$/) {
$baseUnit = "$1\@.$2";
$prevUnitFile = "/etc/systemd/system/$baseUnit";
$newUnitFile = "$out/etc/systemd/system/$baseUnit";
}
my $baseName = $baseUnit;
$baseName =~ s/\.[a-z]*$//;
if (-e $prevUnitFile && ($state->{state} eq "active" || $state->{state} eq "activating")) {
if (! -e $newUnitFile || abs_path($newUnitFile) eq "/dev/null") {
my $unitInfo = parseUnit($prevUnitFile);
$unitsToStop{$unit} = 1 if boolIsTrue($unitInfo->{'X-StopOnRemoval'} // "yes");
}
elsif ($unit =~ /\.target$/) {
my $unitInfo = parseUnit($newUnitFile);
# Cause all active target units to be restarted below.
# This should start most changed units we stop here as
# well as any new dependencies (including new mounts and
# swap devices). FIXME: the suspend target is sometimes
# active after the system has resumed, which probably
# should not be the case. Just ignore it.
if ($unit ne "suspend.target" && $unit ne "hibernate.target" && $unit ne "hybrid-sleep.target") {
unless (boolIsTrue($unitInfo->{'RefuseManualStart'} // "no") || boolIsTrue($unitInfo->{'X-OnlyManualStart'} // "no")) {
$unitsToStart{$unit} = 1;
recordUnit($startListFile, $unit);
# Don't spam the user with target units that always get started.
$unitsToFilter{$unit} = 1;
}
}
# Stop targets that have X-StopOnReconfiguration set.
# This is necessary to respect dependency orderings
# involving targets: if unit X starts after target Y and
# target Y starts after unit Z, then if X and Z have both
# changed, then X should be restarted after Z. However,
# if target Y is in the "active" state, X and Z will be
# restarted at the same time because X's dependency on Y
# is already satisfied. Thus, we need to stop Y first.
# Stopping a target generally has no effect on other units
# (unless there is a PartOf dependency), so this is just a
# bookkeeping thing to get systemd to do the right thing.
if (boolIsTrue($unitInfo->{'X-StopOnReconfiguration'} // "no")) {
$unitsToStop{$unit} = 1;
}
}
elsif (fingerprintUnit($prevUnitFile) ne fingerprintUnit($newUnitFile)) {
if ($unit eq "sysinit.target" || $unit eq "basic.target" || $unit eq "multi-user.target" || $unit eq "graphical.target") {
# Do nothing. These cannot be restarted directly.
} elsif ($unit =~ /\.mount$/) {
# Reload the changed mount unit to force a remount.
$unitsToReload{$unit} = 1;
recordUnit($reloadListFile, $unit);
} elsif ($unit =~ /\.socket$/ || $unit =~ /\.path$/ || $unit =~ /\.slice$/) {
# FIXME: do something?
} else {
my $unitInfo = parseUnit($newUnitFile);
if (boolIsTrue($unitInfo->{'X-ReloadIfChanged'} // "no")) {
$unitsToReload{$unit} = 1;
recordUnit($reloadListFile, $unit);
}
elsif (!boolIsTrue($unitInfo->{'X-RestartIfChanged'} // "yes") || boolIsTrue($unitInfo->{'RefuseManualStop'} // "no") || boolIsTrue($unitInfo->{'X-OnlyManualStart'} // "no")) {
$unitsToSkip{$unit} = 1;
} else {
if (!boolIsTrue($unitInfo->{'X-StopIfChanged'} // "yes")) {
# This unit should be restarted instead of
# stopped and started.
$unitsToRestart{$unit} = 1;
recordUnit($restartListFile, $unit);
} else {
# If this unit is socket-activated, then stop the
# socket unit(s) as well, and restart the
# socket(s) instead of the service.
my $socketActivated = 0;
if ($unit =~ /\.service$/) {
my @sockets = split / /, ($unitInfo->{Sockets} // "");
if (scalar @sockets == 0) {
@sockets = ("$baseName.socket");
}
foreach my $socket (@sockets) {
if (defined $activePrev->{$socket}) {
$unitsToStop{$socket} = 1;
$unitsToStart{$socket} = 1;
recordUnit($startListFile, $socket);
$socketActivated = 1;
}
}
}
# If the unit is not socket-activated, record
# that this unit needs to be started below.
# We write this to a file to ensure that the
# service gets restarted if we're interrupted.
if (!$socketActivated) {
$unitsToStart{$unit} = 1;
recordUnit($startListFile, $unit);
}
$unitsToStop{$unit} = 1;
}
}
}
}
}
}
sub pathToUnitName {
my ($path) = @_;
# Use current version of systemctl binary before daemon is reexeced.
open my $cmd, "-|", "$curSystemd/systemd-escape", "--suffix=mount", "-p", $path
or die "Unable to escape $path!\n";
my $escaped = join "", <$cmd>;
chomp $escaped;
close $cmd or die;
return $escaped;
}
sub unique {
my %seen;
my @res;
foreach my $name (@_) {
next if $seen{$name};
$seen{$name} = 1;
push @res, $name;
}
return @res;
}
# Compare the previous and new fstab to figure out which filesystems
# need a remount or need to be unmounted. New filesystems are mounted
# automatically by starting local-fs.target. FIXME: might be nicer if
# we generated units for all mounts; then we could unify this with the
# unit checking code above.
my ($prevFss, $prevSwaps) = parseFstab "/etc/fstab";
my ($newFss, $newSwaps) = parseFstab "$out/etc/fstab";
foreach my $mountPoint (keys %$prevFss) {
my $prev = $prevFss->{$mountPoint};
my $new = $newFss->{$mountPoint};
my $unit = pathToUnitName($mountPoint);
if (!defined $new) {
# Filesystem entry disappeared, so unmount it.
$unitsToStop{$unit} = 1;
} elsif ($prev->{fsType} ne $new->{fsType} || $prev->{device} ne $new->{device}) {
# Filesystem type or device changed, so unmount and mount it.
$unitsToStop{$unit} = 1;
$unitsToStart{$unit} = 1;
recordUnit($startListFile, $unit);
} elsif ($prev->{options} ne $new->{options}) {
# Mount options changes, so remount it.
$unitsToReload{$unit} = 1;
recordUnit($reloadListFile, $unit);
}
}
# Also handles swap devices.
foreach my $device (keys %$prevSwaps) {
my $prev = $prevSwaps->{$device};
my $new = $newSwaps->{$device};
if (!defined $new) {
# Swap entry disappeared, so turn it off. Can't use
# "systemctl stop" here because systemd has lots of alias
# units that prevent a stop from actually calling
# "swapoff".
print STDERR "stopping swap device: $device\n";
system("@utillinux@/sbin/swapoff", $device);
}
# FIXME: update swap options (i.e. its priority).
}
# Should we have systemd re-exec itself?
my $prevSystemd = abs_path("/proc/1/exe") // "/unknown";
my $newSystemd = abs_path("@systemd@/lib/systemd/systemd") or die;
my $restartSystemd = $prevSystemd ne $newSystemd;
sub filterUnits {
my ($units) = @_;
my @res;
foreach my $unit (sort(keys %{$units})) {
push @res, $unit if !defined $unitsToFilter{$unit};
}
return @res;
}
my @unitsToStopFiltered = filterUnits(\%unitsToStop);
my @unitsToStartFiltered = filterUnits(\%unitsToStart);
# Show dry-run actions.
if ($action eq "dry-activate") {
print STDERR "would stop the following units: ", join(", ", @unitsToStopFiltered), "\n"
if scalar @unitsToStopFiltered > 0;
print STDERR "would NOT stop the following changed units: ", join(", ", sort(keys %unitsToSkip)), "\n"
if scalar(keys %unitsToSkip) > 0;
print STDERR "would restart systemd\n" if $restartSystemd;
print STDERR "would restart the following units: ", join(", ", sort(keys %unitsToRestart)), "\n"
if scalar(keys %unitsToRestart) > 0;
print STDERR "would start the following units: ", join(", ", @unitsToStartFiltered), "\n"
if scalar @unitsToStartFiltered;
print STDERR "would reload the following units: ", join(", ", sort(keys %unitsToReload)), "\n"
if scalar(keys %unitsToReload) > 0;
exit 0;
}
syslog(LOG_NOTICE, "switching to system configuration $out");
if (scalar (keys %unitsToStop) > 0) {
print STDERR "stopping the following units: ", join(", ", @unitsToStopFiltered), "\n"
if scalar @unitsToStopFiltered;
# Use current version of systemctl binary before daemon is reexeced.
system("$curSystemd/systemctl", "stop", "--", sort(keys %unitsToStop)); # FIXME: ignore errors?
}
print STDERR "NOT restarting the following changed units: ", join(", ", sort(keys %unitsToSkip)), "\n"
if scalar(keys %unitsToSkip) > 0;
# 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 $res = 2;
# Restart systemd if necessary. Note that this is done using the
# current version of systemd, just in case the new one has trouble
# communicating with the running pid 1.
if ($restartSystemd) {
print STDERR "restarting systemd...\n";
system("$curSystemd/systemctl", "daemon-reexec") == 0 or $res = 2;
}
# Forget about previously failed services.
system("@systemd@/bin/systemctl", "reset-failed");
# Make systemd reload its units.
system("@systemd@/bin/systemctl", "daemon-reload") == 0 or $res = 3;
# Reload user units
open my $listActiveUsers, '-|', '@systemd@/bin/loginctl', 'list-users', '--no-legend';
while (my $f = <$listActiveUsers>) {
next unless $f =~ /^\s*(?<uid>\d+)\s+(?<user>\S+)/;
my ($uid, $name) = ($+{uid}, $+{user});
print STDERR "reloading user units for $name...\n";
system("@su@", "-s", "@shell@", "-l", $name, "-c",
"export XDG_RUNTIME_DIR=/run/user/$uid; " .
"$curSystemd/systemctl --user daemon-reexec; " .
"@systemd@/bin/systemctl --user start nixos-activation.service");
}
close $listActiveUsers;
# Set the new tmpfiles
print STDERR "setting up tmpfiles\n";
system("@systemd@/bin/systemd-tmpfiles", "--create", "--remove", "--exclude-prefix=/dev") == 0 or $res = 3;
# Reload units that need it. This includes remounting changed mount
# units.
if (scalar(keys %unitsToReload) > 0) {
print STDERR "reloading the following units: ", join(", ", sort(keys %unitsToReload)), "\n";
system("@systemd@/bin/systemctl", "reload", "--", sort(keys %unitsToReload)) == 0 or $res = 4;
unlink($reloadListFile);
}
# Restart changed services (those that have to be restarted rather
# than stopped and started).
if (scalar(keys %unitsToRestart) > 0) {
print STDERR "restarting the following units: ", join(", ", sort(keys %unitsToRestart)), "\n";
system("@systemd@/bin/systemctl", "restart", "--", sort(keys %unitsToRestart)) == 0 or $res = 4;
unlink($restartListFile);
}
# Start all active targets, as well as changed units we stopped above.
# The latter is necessary because some may not be dependencies of the
# targets (i.e., they were manually started). FIXME: detect units
# that are symlinks to other units. We shouldn't start both at the
# same time because we'll get a "Failed to add path to set" error from
# systemd.
print STDERR "starting the following units: ", join(", ", @unitsToStartFiltered), "\n"
if scalar @unitsToStartFiltered;
system("@systemd@/bin/systemctl", "start", "--", sort(keys %unitsToStart)) == 0 or $res = 4;
unlink($startListFile);
# Print failed and new units.
my (@failed, @new, @restarting);
my $activeNew = getActiveUnits;
while (my ($unit, $state) = each %{$activeNew}) {
if ($state->{state} eq "failed") {
push @failed, $unit;
}
elsif ($state->{state} eq "auto-restart") {
# A unit in auto-restart state is a failure *if* it previously failed to start
my $lines = `@systemd@/bin/systemctl show '$unit'`;
my $info = {};
parseKeyValues($info, split("\n", $lines));
if ($info->{ExecMainStatus} ne '0') {
push @failed, $unit;
}
}
elsif ($state->{state} ne "failed" && !defined $activePrev->{$unit}) {
push @new, $unit;
}
}
print STDERR "the following new units were started: ", join(", ", sort(@new)), "\n"
if scalar @new > 0;
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");
}
$res = 4;
}
if ($res == 0) {
syslog(LOG_NOTICE, "finished switching to system configuration $out");
} else {
syslog(LOG_ERR, "switching to system configuration $out failed (status $res)");
}
exit $res;