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nixos/systemd: migrate systemd-timesync state when required

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Somewhen between systemd v239 and v242 upstream decided to no longer run
a few system services with `DyanmicUser=1` but failed to provide a
migration path for all the state those services left behind.

For the case of systemd-timesync the state has to be moved from
/var/lib/private/systemd/timesync to /var/lib/systemd/timesync if
/var/lib/systemd/timesync is currently a symlink.

We only do this if the stateVersion is still below 19.09 to avoid
starting to have an ever growing activation script for (then) ancient
systemd migrations that are no longer required.

See https://github.com/systemd/systemd/issues/12131 for details about
the missing migration path and related discussion.
This commit is contained in:
Andreas Rammhold 2019-05-15 11:05:37 +02:00
parent bc71b6eaf6
commit 024a383d64
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GPG key ID: 74908259861E8386
5 changed files with 77 additions and 3 deletions
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16
nixos/doc/manual/release-notes/rl-1909.xml
View file

@ -172,6 +172,20 @@
which is linked to <literal>fr-toutesvariantes.{aff,dic}</literal>.
</para>
</listitem>
</itemizedlist>
<listitem>
<para>
With the upgrade to systemd version 242 the <literal>systemd-timesyncd</literal>
service is no longer using <literal>DynamicUser=yes</literal>. In order for the
upgrade to work we rely on an activation script to move the state from the old
to the new directory. The older directory (prior <literal>19.09</literal>) was
<literal>/var/lib/private/systemd/timesync</literal>.
</para>
<para>
As long as the <literal>system.config.stateVersion</literal> is below
<literal>19.09</literal> the state folder will migrated to its proper location
(<literal>/var/lib/systemd/timesync</literal>), if required.
</para>
</listitem>
</itemizedlist>
</section>
</section>

2
nixos/modules/system/boot/systemd.nix
View file

@ -940,7 +940,6 @@ in
# Don't bother with certain units in containers.
systemd.services.systemd-remount-fs.unitConfig.ConditionVirtualization = "!container";
systemd.services.systemd-random-seed.unitConfig.ConditionVirtualization = "!container";
};
# FIXME: Remove these eventually.
@ -949,5 +948,4 @@ in
(mkRenamedOptionModule [ "boot" "systemd" "targets" ] [ "systemd" "targets" ])
(mkRenamedOptionModule [ "boot" "systemd" "services" ] [ "systemd" "services" ])
];
}

9
nixos/modules/system/boot/timesyncd.nix
View file

@ -40,6 +40,15 @@ with lib;
users.users.systemd-timesync.uid = config.ids.uids.systemd-timesync;
users.groups.systemd-timesync.gid = config.ids.gids.systemd-timesync;
system.activationScripts.systemd-timesyncd-migration = mkIf (versionOlder config.system.stateVersion "19.09") ''
# workaround an issue of systemd-timesyncd not starting due to upstream systemd reverting their dynamic users changes
# - https://github.com/NixOS/nixpkgs/pull/61321#issuecomment-492423742
# - https://github.com/systemd/systemd/issues/12131
if [ -L /var/lib/systemd/timesync ]; then
rm /var/lib/systemd/timesync
mv /var/lib/private/systemd/timesync /var/lib/systemd/timesync
fi
'';
};
}

1
nixos/tests/all-tests.nix
View file

@ -237,6 +237,7 @@ in
syncthing-relay = handleTest ./syncthing-relay.nix {};
systemd = handleTest ./systemd.nix {};
systemd-confinement = handleTest ./systemd-confinement.nix {};
systemd-timesyncd = handleTest ./systemd-timesyncd.nix {};
pdns-recursor = handleTest ./pdns-recursor.nix {};
taskserver = handleTest ./taskserver.nix {};
telegraf = handleTest ./telegraf.nix {};

52
nixos/tests/systemd-timesyncd.nix Normal file
View file

@ -0,0 +1,52 @@
# Regression test for systemd-timesync having moved the state directory without
# upstream providing a migration path. https://github.com/systemd/systemd/issues/12131
import ./make-test.nix (let
common = { lib, ... }: {
# override the `false` value from the qemu-vm base profile
services.timesyncd.enable = lib.mkForce true;
};
mkVM = conf: { imports = [ conf common ]; };
in {
name = "systemd-timesyncd";
nodes = {
current = mkVM {};
pre1909 = mkVM ({lib, ... }: with lib; {
# create the path that should be migrated by our activation script when
# upgrading to a newer nixos version
system.stateVersion = "19.03";
system.activationScripts.simulate-old-timesync-state-dir = mkBefore ''
rm -f /var/lib/systemd/timesync
mkdir -p /var/lib/systemd /var/lib/private/systemd/timesync
ln -s /var/lib/private/systemd/timesync /var/lib/systemd/timesync
chown systemd-timesync: /var/lib/private/systemd/timesync
'';
});
};
testScript = ''
startAll;
$current->succeed('systemctl status systemd-timesyncd.service');
# on a new install with a recent systemd there should not be any
# leftovers from the dynamic user mess
$current->succeed('test -e /var/lib/systemd/timesync');
$current->succeed('test ! -L /var/lib/systemd/timesync');
# timesyncd should be running on the upgrading system since we fixed the
# file bits in the activation script
$pre1909->succeed('systemctl status systemd-timesyncd.service');
# the path should be gone after the migration
$pre1909->succeed('test ! -e /var/lib/private/systemd/timesync');
# and the new path should no longer be a symlink
$pre1909->succeed('test -e /var/lib/systemd/timesync');
$pre1909->succeed('test ! -L /var/lib/systemd/timesync');
# after a restart things should still work and not fail in the activation
# scripts and cause the boot to fail..
$pre1909->shutdown;
$pre1909->start;
$pre1909->succeed('systemctl status systemd-timesyncd.service');
'';
})