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Merge pull request #141192 from helsinki-systems/feat/improved-socket…
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…-handling2

nixos/switch-to-configuration: Improve socket and timer handling, clean up, minor fixes, add test
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@Mic92
Mic92 authored Oct 18, 2021
2 parents b04f913 + 4cdbb2d commit 57961d2
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9 changes: 9 additions & 0 deletions nixos/doc/manual/from_md/release-notes/rl-2111.section.xml
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Expand Up @@ -1554,6 +1554,15 @@ Superuser created successfully.
encapsulation.
</para>
</listitem>
<listitem>
<para>
Changing systemd <literal>.socket</literal> units now restarts
them and stops the service that is activated by them.
Additionally, services with
<literal>stopOnChange = false</literal> don’t break anymore
when they are socket-activated.
</para>
</listitem>
</itemizedlist>
</section>
</section>
2 changes: 2 additions & 0 deletions nixos/doc/manual/release-notes/rl-2111.section.md
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Original file line number Diff line number Diff line change
Expand Up @@ -449,3 +449,5 @@ In addition to numerous new and upgraded packages, this release has the followin
- The `networking` module has a new `networking.fooOverUDP` option to configure Foo-over-UDP encapsulations.

- `networking.sits` now supports Foo-over-UDP encapsulation.

- Changing systemd `.socket` units now restarts them and stops the service that is activated by them. Additionally, services with `stopOnChange = false` don't break anymore when they are socket-activated.
274 changes: 190 additions & 84 deletions nixos/modules/system/activation/switch-to-configuration.pl
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Original file line number Diff line number Diff line change
Expand Up @@ -11,21 +11,23 @@

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/nixos/start-list";
my $restartListFile = "/run/nixos/restart-list";
my $reloadListFile = "/run/nixos/reload-list";

# Parse restart/reload requests by the activation script
# Parse restart/reload requests by the activation script.
# Activation scripts may write newline-separated units to this
# file and switch-to-configuration will handle them. While
# `stopIfChanged = true` is ignored, switch-to-configuration will
# handle `restartIfChanged = false` and `reloadIfChanged = true`.
# This also works for socket-activated units.
my $restartByActivationFile = "/run/nixos/activation-restart-list";
my $reloadByActivationFile = "/run/nixos/activation-reload-list";
my $dryRestartByActivationFile = "/run/nixos/dry-activation-restart-list";
my $dryReloadByActivationFile = "/run/nixos/dry-activation-reload-list";

make_path("/run/nixos", { mode => 0755 });
make_path("/run/nixos", { mode => oct(755) });

my $action = shift @ARGV;

Expand Down Expand Up @@ -147,6 +149,92 @@ sub fingerprintUnit {
return abs_path($s) . (-f "${s}.d/overrides.conf" ? " " . abs_path "${s}.d/overrides.conf" : "");
}

sub handleModifiedUnit {
my ($unit, $baseName, $newUnitFile, $activePrev, $unitsToStop, $unitsToStart, $unitsToReload, $unitsToRestart, $unitsToSkip) = @_;

if ($unit eq "sysinit.target" || $unit eq "basic.target" || $unit eq "multi-user.target" || $unit eq "graphical.target" || $unit =~ /\.slice$/ || $unit =~ /\.path$/) {
# Do nothing. These cannot be restarted directly.
# Slices and Paths don't have to be restarted since
# properties (resource limits and inotify watches)
# seem to get applied on daemon-reload.
} elsif ($unit =~ /\.mount$/) {
# Reload the changed mount unit to force a remount.
$unitsToReload->{$unit} = 1;
recordUnit($reloadListFile, $unit);
} 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 this unit is socket-activated, then stop it instead
# of restarting it to make sure the new version of it is
# socket-activated.
my $socketActivated = 0;
if ($unit =~ /\.service$/) {
my @sockets = split / /, ($unitInfo->{Sockets} // "");
if (scalar @sockets == 0) {
@sockets = ("$baseName.socket");
}
foreach my $socket (@sockets) {
if (-e "$out/etc/systemd/system/$socket") {
$socketActivated = 1;
$unitsToStop->{$unit} = 1;
# If the socket was not running previously,
# start it now.
if (not defined $activePrev->{$socket}) {
$unitsToStart->{$socket} = 1;
}
}
}
}

# Don't do the rest of this for socket-activated units
# because we handled these above where we stop the unit.
# Since only services can be socket-activated, the
# following condition always evaluates to `true` for
# non-service units.
if ($socketActivated) {
return;
}

# If we are restarting a socket, also stop the corresponding
# service. This is required because restarting a socket
# when the service is already activated fails.
if ($unit =~ /\.socket$/) {
my $service = $unitInfo->{Service} // "";
if ($service eq "") {
$service = "$baseName.service";
}
if (defined $activePrev->{$service}) {
$unitsToStop->{$service} = 1;
}
$unitsToRestart->{$unit} = 1;
recordUnit($restartListFile, $unit);
} else {
# Always restart non-services instead of stopping and starting them
# because it doesn't make sense to stop them with a config from
# the old evaluation.
if (!boolIsTrue($unitInfo->{'X-StopIfChanged'} // "yes") || $unit !~ /\.service$/) {
# This unit should be restarted instead of
# stopped and started.
$unitsToRestart->{$unit} = 1;
recordUnit($restartListFile, $unit);
} else {
# We write to a file to ensure that the
# service gets restarted if we're interrupted.
$unitsToStart->{$unit} = 1;
recordUnit($startListFile, $unit);
$unitsToStop->{$unit} = 1;
}
}
}
}
}

# Figure out what units need to be stopped, started, restarted or reloaded.
my (%unitsToStop, %unitsToSkip, %unitsToStart, %unitsToRestart, %unitsToReload);

Expand Down Expand Up @@ -219,65 +307,7 @@ sub fingerprintUnit {
}

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;
# Only restart sockets that actually
# exist in new configuration:
if (-e "$out/etc/systemd/system/$socket") {
$unitsToStart{$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;
}
}
}
handleModifiedUnit($unit, $baseName, $newUnitFile, $activePrev, \%unitsToStop, \%unitsToStart, \%unitsToReload, \%unitsToRestart, %unitsToSkip);
}
}
}
Expand Down Expand Up @@ -362,8 +392,6 @@ sub filterUnits {
}

my @unitsToStopFiltered = filterUnits(\%unitsToStop);
my @unitsToStartFiltered = filterUnits(\%unitsToStart);


# Show dry-run actions.
if ($action eq "dry-activate") {
Expand All @@ -375,21 +403,44 @@ sub filterUnits {
print STDERR "would activate the configuration...\n";
system("$out/dry-activate", "$out");

$unitsToRestart{$_} = 1 foreach
split('\n', read_file($dryRestartByActivationFile, err_mode => 'quiet') // "");
# Handle the activation script requesting the restart or reload of a unit.
my %unitsToAlsoStop;
my %unitsToAlsoSkip;
foreach (split('\n', read_file($dryRestartByActivationFile, err_mode => 'quiet') // "")) {
my $unit = $_;
my $baseUnit = $unit;
my $newUnitFile = "$out/etc/systemd/system/$baseUnit";

# Detect template instances.
if (!-e $newUnitFile && $unit =~ /^(.*)@[^\.]*\.(.*)$/) {
$baseUnit = "$1\@.$2";
$newUnitFile = "$out/etc/systemd/system/$baseUnit";
}

my $baseName = $baseUnit;
$baseName =~ s/\.[a-z]*$//;

$unitsToReload{$_} = 1 foreach
split('\n', read_file($dryReloadByActivationFile, err_mode => 'quiet') // "");
handleModifiedUnit($unit, $baseName, $newUnitFile, $activePrev, \%unitsToAlsoStop, \%unitsToStart, \%unitsToReload, \%unitsToRestart, %unitsToAlsoSkip);
}
unlink($dryRestartByActivationFile);

my @unitsToAlsoStopFiltered = filterUnits(\%unitsToAlsoStop);
if (scalar(keys %unitsToAlsoStop) > 0) {
print STDERR "would stop the following units as well: ", join(", ", @unitsToAlsoStopFiltered), "\n"
if scalar @unitsToAlsoStopFiltered;
}

print STDERR "would NOT restart the following changed units as well: ", join(", ", sort(keys %unitsToAlsoSkip)), "\n"
if scalar(keys %unitsToAlsoSkip) > 0;

print STDERR "would restart systemd\n" if $restartSystemd;
print STDERR "would reload the following units: ", join(", ", sort(keys %unitsToReload)), "\n"
if scalar(keys %unitsToReload) > 0;
print STDERR "would restart the following units: ", join(", ", sort(keys %unitsToRestart)), "\n"
if scalar(keys %unitsToRestart) > 0;
my @unitsToStartFiltered = filterUnits(\%unitsToStart);
print STDERR "would start the following units: ", join(", ", @unitsToStartFiltered), "\n"
if scalar @unitsToStartFiltered;
print STDERR "would reload the following units: ", join(", ", sort(keys %unitsToReload)), "\n"
if scalar(keys %unitsToReload) > 0;
unlink($dryRestartByActivationFile);
unlink($dryReloadByActivationFile);
exit 0;
}

Expand All @@ -400,7 +451,7 @@ sub filterUnits {
print STDERR "stopping the following units: ", join(", ", @unitsToStopFiltered), "\n"
if scalar @unitsToStopFiltered;
# Use current version of systemctl binary before daemon is reexeced.
system("$curSystemd/systemctl", "stop", "--", sort(keys %unitsToStop)); # FIXME: ignore errors?
system("$curSystemd/systemctl", "stop", "--", sort(keys %unitsToStop));
}

print STDERR "NOT restarting the following changed units: ", join(", ", sort(keys %unitsToSkip)), "\n"
Expand All @@ -414,12 +465,38 @@ sub filterUnits {

# Handle the activation script requesting the restart or reload of a unit.
# We can only restart and reload (not stop/start) because the units to be
# stopped are already stopped before the activation script is run.
$unitsToRestart{$_} = 1 foreach
split('\n', read_file($restartByActivationFile, err_mode => 'quiet') // "");
# stopped are already stopped before the activation script is run. We do however
# make an exception for services that are socket-activated and that have to be stopped
# instead of being restarted.
my %unitsToAlsoStop;
my %unitsToAlsoSkip;
foreach (split('\n', read_file($restartByActivationFile, err_mode => 'quiet') // "")) {
my $unit = $_;
my $baseUnit = $unit;
my $newUnitFile = "$out/etc/systemd/system/$baseUnit";

$unitsToReload{$_} = 1 foreach
split('\n', read_file($reloadByActivationFile, err_mode => 'quiet') // "");
# Detect template instances.
if (!-e $newUnitFile && $unit =~ /^(.*)@[^\.]*\.(.*)$/) {
$baseUnit = "$1\@.$2";
$newUnitFile = "$out/etc/systemd/system/$baseUnit";
}

my $baseName = $baseUnit;
$baseName =~ s/\.[a-z]*$//;

handleModifiedUnit($unit, $baseName, $newUnitFile, $activePrev, \%unitsToAlsoStop, \%unitsToStart, \%unitsToReload, \%unitsToRestart, %unitsToAlsoSkip);
}
unlink($restartByActivationFile);

my @unitsToAlsoStopFiltered = filterUnits(\%unitsToAlsoStop);
if (scalar(keys %unitsToAlsoStop) > 0) {
print STDERR "stopping the following units as well: ", join(", ", @unitsToAlsoStopFiltered), "\n"
if scalar @unitsToAlsoStopFiltered;
system("$curSystemd/systemctl", "stop", "--", sort(keys %unitsToAlsoStop));
}

print STDERR "NOT restarting the following changed units as well: ", join(", ", sort(keys %unitsToAlsoSkip)), "\n"
if scalar(keys %unitsToAlsoSkip) > 0;

# Restart systemd if necessary. Note that this is done using the
# current version of systemd, just in case the new one has trouble
Expand Down Expand Up @@ -460,14 +537,40 @@ sub filterUnits {
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);
unlink($reloadByActivationFile);
}

# 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;

# We split the units to be restarted into sockets and non-sockets.
# This is because restarting sockets may fail which is not bad by
# itself but which will prevent changes on the sockets. We usually
# restart the socket and stop the service before that. Restarting
# the socket will fail however when the service was re-activated
# in the meantime. There is no proper way to prevent that from happening.
my @unitsWithErrorHandling = grep { $_ !~ /\.socket$/ } sort(keys %unitsToRestart);
my @unitsWithoutErrorHandling = grep { $_ =~ /\.socket$/ } sort(keys %unitsToRestart);

if (scalar(@unitsWithErrorHandling) > 0) {
system("@systemd@/bin/systemctl", "restart", "--", @unitsWithErrorHandling) == 0 or $res = 4;
}
if (scalar(@unitsWithoutErrorHandling) > 0) {
# Don't print warnings from systemctl
no warnings 'once';
open(OLDERR, ">&", \*STDERR);
close(STDERR);

my $ret = system("@systemd@/bin/systemctl", "restart", "--", @unitsWithoutErrorHandling);

# Print stderr again
open(STDERR, ">&OLDERR");

if ($ret ne 0) {
print STDERR "warning: some sockets failed to restart. Please check your journal (journalctl -eb) and act accordingly.\n";
}
}
unlink($restartListFile);
unlink($restartByActivationFile);
}
Expand All @@ -478,14 +581,15 @@ sub filterUnits {
# 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.
my @unitsToStartFiltered = filterUnits(\%unitsToStart);
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 (@failed, @new);
my $activeNew = getActiveUnits;
while (my ($unit, $state) = each %{$activeNew}) {
if ($state->{state} eq "failed") {
Expand All @@ -501,7 +605,9 @@ sub filterUnits {
push @failed, $unit;
}
}
elsif ($state->{state} ne "failed" && !defined $activePrev->{$unit}) {
# Ignore scopes since they are not managed by this script but rather
# created and managed by third-party services via the systemd dbus API.
elsif ($state->{state} ne "failed" && !defined $activePrev->{$unit} && $unit !~ /\.scope$/) {
push @new, $unit;
}
}
Expand Down
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