From 61628287bd6d5115d96a4bdbd70964efd7a5940e Mon Sep 17 00:00:00 2001
From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Thu, 2 May 2024 06:18:52 +0900
Subject: journal: explicitly sync namespaced journals before stopping socket
 units

Otherwise, if a service unit that requests LogNamespace= stopped before
systemd-journald@.service is started, logs generated by the service will be
lost, as systemd-journald@.socket is stopped and
systemd-journald@.service will never started.

To prevent the issue, let's introduce another implicit dependency to
a oneshot service that explicitly synchronizes a namespaced journal file
when the log namespace is not needed anymore.

Fixes #32604.
---
 units/meson.build                    |  1 +
 units/systemd-journald-sync@.service | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+)
 create mode 100644 units/systemd-journald-sync@.service

(limited to 'units')

diff --git a/units/meson.build b/units/meson.build
index 5b2410fe93..b231341a1f 100644
--- a/units/meson.build
+++ b/units/meson.build
@@ -403,6 +403,7 @@ units = [
           'file' : 'systemd-journald-dev-log.socket',
           'symlinks' : ['sockets.target.wants/'],
         },
+        { 'file' : 'systemd-journald-sync@.service' },
         { 'file' : 'systemd-journald-varlink@.socket' },
         {
           'file' : 'systemd-journald.service.in',
diff --git a/units/systemd-journald-sync@.service b/units/systemd-journald-sync@.service
new file mode 100644
index 0000000000..3eafcd0359
--- /dev/null
+++ b/units/systemd-journald-sync@.service
@@ -0,0 +1,24 @@
+#  SPDX-License-Identifier: LGPL-2.1-or-later
+#
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Sync Journal for Namespace %i
+Documentation=man:systemd-journald.service(8) man:journald.conf(5)
+
+# At the time when journalctl in ExecStop= is invoked,
+# systemd-journald@.service may not be started yet. Hence, both socket
+# units must be active when journalctl is invoked.
+Requires=systemd-journald@%i.socket systemd-journald-varlink@%i.socket
+After=systemd-journald@%i.socket systemd-journald-varlink@%i.socket
+StopWhenUnneeded=yes
+
+[Service]
+ExecStop=journalctl --namespace=%i --sync
+Type=oneshot
+RemainAfterExit=yes
-- 
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