[libvirt] [PATCH] libvirtd: systemd: add special target for system shutdown

[Nikolay Shirokovskiy]

It is already discussed in "[RFC] daemon: remove hardcode dep on libvirt-guests" [1].

Mgmt can use means to save/restore domains on system shutdown/boot other then
libvirt-guests.service. Thus we need to specify appropriate ordering dependency between
libvirtd, domains and save/restore service. This patch takes approach suggested
in RFC and introduces a systemd target, so that ordering can be built next way:

libvirtd -> domain -> virt-guest-shutdown.target -> save-restore.service.

This way domains are decoupled from specific shutdown service via intermediate
target.

[1] https://www.redhat.com/archives/libvir-list/2016-September/msg01353.html
---
 daemon/Makefile.am                | 4 ++++
 daemon/virt-guest-shutdown.target | 3 +++
 libvirt.spec.in                   | 1 +
 src/util/virsystemd.c             | 4 ++--
 tools/libvirt-guests.service.in   | 2 ++
 5 files changed, 12 insertions(+), 2 deletions(-)
 create mode 100644 daemon/virt-guest-shutdown.target

diff --git a/daemon/Makefile.am b/daemon/Makefile.am
index 927d16f..463db6e 100644
--- a/daemon/Makefile.am
+++ b/daemon/Makefile.am
@@ -67,6 +67,7 @@ EXTRA_DIST =						\
 	libvirt.rules					\
 	libvirtd.sasl					\
 	libvirtd.service.in				\
+	virt-guest-shutdown.target		\
 	libvirtd.sysconf				\
 	libvirtd.sysctl					\
 	libvirtd.aug                                    \
@@ -456,8 +457,11 @@ install-init-systemd: install-sysconfig libvirtd.service
 	$(MKDIR_P) $(DESTDIR)$(SYSTEMD_UNIT_DIR)
 	$(INSTALL_DATA) libvirtd.service \
 	  $(DESTDIR)$(SYSTEMD_UNIT_DIR)/libvirtd.service
+	$(INSTALL_DATA) virt-guest-shutdown.target \
+	  $(DESTDIR)$(SYSTEMD_UNIT_DIR)/virt-guest-shutdown.target
 
 uninstall-init-systemd: uninstall-sysconfig
+	rm -f $(DESTDIR)$(SYSTEMD_UNIT_DIR)/virt-guest-shutdown.target
 	rm -f $(DESTDIR)$(SYSTEMD_UNIT_DIR)/libvirtd.service
 	rmdir $(DESTDIR)$(SYSTEMD_UNIT_DIR) || :
 else ! LIBVIRT_INIT_SCRIPT_SYSTEMD
diff --git a/daemon/virt-guest-shutdown.target b/daemon/virt-guest-shutdown.target
new file mode 100644
index 0000000..bf87652
--- /dev/null
+++ b/daemon/virt-guest-shutdown.target
@@ -0,0 +1,3 @@
+[Unit]
+Description=Libvirt guests shutdown
+Documentation=http://libvirt.org
diff --git a/libvirt.spec.in b/libvirt.spec.in
index 00b95b8..82a7363 100644
--- a/libvirt.spec.in
+++ b/libvirt.spec.in
@@ -1579,6 +1579,7 @@ exit 0
 
 %if %{with_systemd}
 %{_unitdir}/libvirtd.service
+%{_unitdir}/virt-guest-shutdown.target
 %{_unitdir}/virtlogd.service
 %{_unitdir}/virtlogd.socket
 %{_unitdir}/virtlockd.service
diff --git a/src/util/virsystemd.c b/src/util/virsystemd.c
index 604dcdd..c8837f9 100644
--- a/src/util/virsystemd.c
+++ b/src/util/virsystemd.c
@@ -370,7 +370,7 @@ int virSystemdCreateMachine(const char *name,
                               3,
                               "Slice", "s", slicename,
                               "After", "as", 1, "libvirtd.service",
-                              "Before", "as", 1, "libvirt-guests.service") < 0)
+                              "Before", "as", 1, "virt-guest-shutdown.target") < 0)
             goto cleanup;
 
         if (error.level == VIR_ERR_ERROR) {
@@ -411,7 +411,7 @@ int virSystemdCreateMachine(const char *name,
                               3,
                               "Slice", "s", slicename,
                               "After", "as", 1, "libvirtd.service",
-                              "Before", "as", 1, "libvirt-guests.service") < 0)
+                              "Before", "as", 1, "virt-guest-shutdown.target") < 0)
             goto cleanup;
     }
 
diff --git a/tools/libvirt-guests.service.in b/tools/libvirt-guests.service.in
index b4f54f2..d0ba655 100644
--- a/tools/libvirt-guests.service.in
+++ b/tools/libvirt-guests.service.in
@@ -1,9 +1,11 @@
 [Unit]
 Description=Suspend/Resume Running libvirt Guests
 Requires=libvirtd.service
+Requires=virt-guest-shutdown.target
 After=network.target
 After=time-sync.target
 After=libvirtd.service
+After=virt-guest-shutdown.target
 Documentation=man:libvirtd(8)
 Documentation=http://libvirt.org
 
-- 
1.8.3.1