diff --git a/Makefile.am b/Makefile.am
index 5cec19fbb8a..6c350b0ec4f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -529,6 +529,7 @@ nodist_systemunit_DATA = \
units/serial-getty@.service \
units/console-getty.service \
units/container-getty@.service \
+ units/system-update-cleanup.service \
units/systemd-initctl.service \
units/systemd-remount-fs.service \
units/systemd-ask-password-wall.service \
@@ -592,6 +593,7 @@ EXTRA_DIST += \
units/console-getty.service.m4.in \
units/container-getty@.service.m4.in \
units/rescue.service.in \
+ units/system-update-cleanup.service.in \
units/systemd-initctl.service.in \
units/systemd-remount-fs.service.in \
units/systemd-update-utmp.service.in \
diff --git a/man/systemd.offline-updates.xml b/man/systemd.offline-updates.xml
index 07a52255127..d673cf5db88 100644
--- a/man/systemd.offline-updates.xml
+++ b/man/systemd.offline-updates.xml
@@ -86,34 +86,44 @@
- The system now continues to boot into default.target, and thus
- into system-update.target. This target pulls in the system update unit,
- which starts the system update script after all file systems have been mounted.
+ The system now continues to boot into default.target, and
+ thus into system-update.target. This target pulls in all system
+ update units. Only one service should perform an update (see the next point), and all
+ the other ones should exit cleanly with a "success" return code and without doing
+ anything. Update services should be ordered after sysinit.target
+ so that the update starts after after all file systems have been mounted.
- As the first step, the update script should check if the
+ As the first step, an update service should check if the
/system-update symlink points to the location used by that update
- script. In case it does not exists or points to a different location, the script must exit
+ service. In case it does not exist or points to a different location, the service must exit
without error. It is possible for multiple update services to be installed, and for multiple
- update scripts to be launched in parallel, and only the one that corresponds to the tool
+ update services to be launched in parallel, and only the one that corresponds to the tool
that created the symlink before reboot should perform any actions. It
is unsafe to run multiple updates in parallel.
- The update script should now do its job. If applicable and possible, it should
- create a file system snapshot, then install all packages.
- After completion (regardless whether the update succeeded or failed) the machine
- must be rebooted, for example by calling systemctl reboot.
- In addition, on failure the script should revert to the old file system snapshot
- (without the symlink).
+ The update service should now do its job. If applicable and possible, it should
+ create a file system snapshot, then install all packages. After completion (regardless
+ whether the update succeeded or failed) the machine must be rebooted, for example by
+ calling systemctl reboot. In addition, on failure the script should
+ revert to the old file system snapshot (without the symlink).
- The system is rebooted. Since the /system-update symlink is gone,
- the generator won't redirect default.target after reboot and the
- system now boots into the default target again.
+ The upgrade scripts should exit only after the update is finished. It is expected
+ that the service which performs the upgrade will cause the machine to reboot after it
+ is done. If the system-update.target is successfully reached, i.e.
+ all update services have run, and the /system-update symlink still
+ exists, it will be removed and the machine rebooted as a safety measure.
+
+
+
+ After a reboot, now that the /system-update symlink is gone,
+ the generator won't redirect default.target anymore and the system
+ now boots into the default target again.
@@ -150,7 +160,8 @@
The update service should declare DefaultDependencies=false,
- and pull in any services it requires explicitly.
+ Requires=sysinit.target, After=sysinit.target,
+ and explicitly pull in any other services it requires.
diff --git a/man/systemd.special.xml b/man/systemd.special.xml
index d977298cd8c..b513a13b5ab 100644
--- a/man/systemd.special.xml
+++ b/man/systemd.special.xml
@@ -102,6 +102,7 @@
sysinit.target,
syslog.socket,
system-update.target,
+ system-update-cleanup.service,
time-sync.target,
timers.target,
umount.target,
@@ -608,15 +609,21 @@
system-update.target
+ system-update-cleanup.service
- A special target unit that is used for off-line system
- updates.
+ A special target unit that is used for offline system updates.
systemd-system-update-generator8
- will redirect the boot process to this target if
- /system-update exists. For more
- information see the System
- Updates Specification.
+ will redirect the boot process to this target if /system-update
+ exists. For more information see
+ systemd.offline-updates7.
+
+
+ Updates should happen before the system-update.target is
+ reached, and the services which implement them should cause the machine to reboot. As
+ a safety measure, if this does not happen, and /system-update
+ still exists after system-update.target is reached,
+ system-update-cleanup.service will remove this symlink and
+ reboot the machine.
diff --git a/units/.gitignore b/units/.gitignore
index 8f4949258e8..8fdb6e9ab5d 100644
--- a/units/.gitignore
+++ b/units/.gitignore
@@ -16,6 +16,7 @@
/rc-local.service
/rescue.service
/serial-getty@.service
+/system-update-cleanup.service
/systemd-ask-password-console.service
/systemd-ask-password-wall.service
/systemd-backlight@.service
diff --git a/units/system-update-cleanup.service.in b/units/system-update-cleanup.service.in
new file mode 100644
index 00000000000..116be8bc2d4
--- /dev/null
+++ b/units/system-update-cleanup.service.in
@@ -0,0 +1,32 @@
+# 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=Remove the Offline System Updates symlink
+Documentation=man:systemd.special(5) man:systemd.offline-updates(7)
+After=system-update.target
+DefaultDependencies=no
+Conflicts=shutdown.target
+
+# system-update-generator uses laccess("/system-update"), while a plain
+# ConditionPathExists=/system-update uses access("/system-update"), so
+# we need an alternate condition to cover the case of a dangling symlink.
+#
+# This service is only invoked if /system-update exists, i.e. if the
+# condition tested by system-update-generator remains true and the system
+# would be diverted into system-update.target again after reboot. This way
+# we guard against being diverted into system-update.target again, which
+# works as a safety measure, but we will not step on the toes of the
+# update script if it successfully removed the symlink and scheduled a
+# reboot or some other action on its own.
+ConditionPathExists=|/system-update
+ConditionPathIsSymbolicLink=|/system-update
+
+[Service]
+Type=oneshot
+ExecStart=/bin/rm -fv /system-update
+ExecStart=@SYSTEMCTL@ reboot
diff --git a/units/system-update.target b/units/system-update.target
index 48d46fcbda9..3542879706f 100644
--- a/units/system-update.target
+++ b/units/system-update.target
@@ -6,11 +6,12 @@
# (at your option) any later version.
[Unit]
-Description=System Update
-Documentation=http://freedesktop.org/wiki/Software/systemd/SystemUpdates
+Description=Offline System Update
+Documentation=man:systemd.offline-updates(7)
Documentation=man:systemd.special(7) man:systemd-system-update-generator(8)
Requires=sysinit.target
Conflicts=shutdown.target
After=sysinit.target
Before=shutdown.target
AllowIsolate=yes
+Wants=system-update-cleanup.service