virNetServerRun: Notify systemd that we're accepting clients

Systemd does not forget about the cases, where client service needs to
wait for daemon service to initialize and start accepting new clients.
Setting a dependency in client is not enough as systemd doesn't know
when the daemon has initialized itself and started accepting new
clients. However, it offers a mechanism to solve this. The daemon needs
to call a special systemd function by which the daemon tells "I'm ready
to accept new clients". This is exactly what we need with
libvirtd-guests (client) and libvirtd (daemon). So now, with this
change, libvirt-guests.service is invoked not any sooner than
libvirtd.service calls the systemd notify function.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

configure.ac

@@ -239,6 +239,7 @@ LIBVIRT_CHECK_SANLOCK
 LIBVIRT_CHECK_SASL
 LIBVIRT_CHECK_SELINUX
 LIBVIRT_CHECK_SSH2
+LIBVIRT_CHECK_SYSTEMD_DAEMON
 LIBVIRT_CHECK_UDEV
 LIBVIRT_CHECK_YAJL
 
@@ -2773,6 +2774,7 @@ LIBVIRT_RESULT_SANLOCK
 LIBVIRT_RESULT_SASL
 LIBVIRT_RESULT_SELINUX
 LIBVIRT_RESULT_SSH2
+LIBVIRT_RESULT_SYSTEMD_DAEMON
 LIBVIRT_RESULT_UDEV
 LIBVIRT_RESULT_YAJL
 AC_MSG_NOTICE([  libxml: $LIBXML_CFLAGS $LIBXML_LIBS])

daemon/libvirtd.service.in

@@ -13,6 +13,7 @@ Documentation=man:libvirtd(8)
 Documentation=http://libvirt.org
 
 [Service]
+Type=notify
 EnvironmentFile=-/etc/sysconfig/libvirtd
 ExecStart=@sbindir@/libvirtd $LIBVIRTD_ARGS
 ExecReload=/bin/kill -HUP $MAINPID

m4/virt-systemd-daemon.m4

@@ -0,0 +1,34 @@
+dnl The libsystemd-daemon.so library
+dnl
+dnl Copyright (C) 2012-2013 Red Hat, Inc.
+dnl
+dnl This library is free software; you can redistribute it and/or
+dnl modify it under the terms of the GNU Lesser General Public
+dnl License as published by the Free Software Foundation; either
+dnl version 2.1 of the License, or (at your option) any later version.
+dnl
+dnl This library is distributed in the hope that it will be useful,
+dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+dnl Lesser General Public License for more details.
+dnl
+dnl You should have received a copy of the GNU Lesser General Public
+dnl License along with this library.  If not, see
+dnl <http://www.gnu.org/licenses/>.
+dnl
+
+AC_DEFUN([LIBVIRT_CHECK_SYSTEMD_DAEMON],[
+  LIBVIRT_CHECK_PKG([SYSTEMD_DAEMON], [libsystemd-daemon], [0.27.1])
+
+    old_CFLAGS="$CFLAGS"
+    old_LIBS="$LIBS"
+    CFLAGS="$CFLAGS $SYSTEMD_DAEMON_CFLAGS"
+    LIBS="$LIBS $SYSTEMD_DAEMON_LIBS"
+    AC_CHECK_FUNCS([sd_notify])
+    CFLAGS="$old_CFLAGS"
+    LIBS="$old_LIBS"
+])
+
+AC_DEFUN([LIBVIRT_RESULT_SYSTEMD_DAEMON],[
+  LIBVIRT_RESULT_LIB([SYSTEMD_DAEMON])
+])

src/Makefile.am

@@ -958,11 +958,11 @@ libvirt_util_la_SOURCES =					\
 libvirt_util_la_CFLAGS = $(CAPNG_CFLAGS) $(YAJL_CFLAGS) $(LIBNL_CFLAGS) \
 		$(AM_CFLAGS) $(AUDIT_CFLAGS) $(DEVMAPPER_CFLAGS) \
 		$(DBUS_CFLAGS) $(LDEXP_LIBM) $(NUMACTL_CFLAGS)	\
-		-I$(top_srcdir)/src/conf
+		$(SYSTEMD_DAEMON_CFLAGS) -I$(top_srcdir)/src/conf
 libvirt_util_la_LIBADD = $(CAPNG_LIBS) $(YAJL_LIBS) $(LIBNL_LIBS) \
 		$(THREAD_LIBS) $(AUDIT_LIBS) $(DEVMAPPER_LIBS) \
 		$(LIB_CLOCK_GETTIME) $(DBUS_LIBS) $(MSCOM_LIBS) $(LIBXML_LIBS) \
-		$(SECDRIVER_LIBS) $(NUMACTL_LIBS)
+		$(SECDRIVER_LIBS) $(NUMACTL_LIBS) $(SYSTEMD_DAEMON_LIBS)
 
 
 noinst_LTLIBRARIES += libvirt_conf.la

src/libvirt_private.syms

@@ -1826,6 +1826,7 @@ virSystemdCreateMachine;
 virSystemdMakeMachineName;
 virSystemdMakeScopeName;
 virSystemdMakeSliceName;
+virSystemdNotifyStartup;
 virSystemdTerminateMachine;
 
 

src/rpc/virnetserver.c

@@ -38,6 +38,7 @@
 #include "virnetservermdns.h"
 #include "virdbus.h"
 #include "virstring.h"
+#include "virsystemd.h"
 
 #ifndef SA_SIGINFO
 # define SA_SIGINFO 0
@@ -1085,6 +1086,10 @@ void virNetServerRun(virNetServerPtr srv)
         goto cleanup;
     }
 
+    /* We are accepting connections now. Notify systemd
+     * so it can start dependent services. */
+    virSystemdNotifyStartup();
+
     VIR_DEBUG("srv=%p quit=%d", srv, srv->quit);
     while (!srv->quit) {
         /* A shutdown timeout is specified, so check

src/util/virsystemd.c

@@ -21,6 +21,10 @@
 
 #include <config.h>
 
+#ifdef WITH_SYSTEMD_DAEMON
+# include <systemd/sd-daemon.h>
+#endif
+
 #include "virsystemd.h"
 #include "virdbus.h"
 #include "virstring.h"
@@ -304,3 +308,11 @@ cleanup:
     VIR_FREE(machinename);
     return ret;
 }
+
+void
+virSystemdNotifyStartup(void)
+{
+#ifdef WITH_SYSTEMD_DAEMON
+    sd_notify(0, "READY=1");
+#endif
+}

src/util/virsystemd.h

@@ -46,4 +46,6 @@ int virSystemdTerminateMachine(const char *name,
                                const char *drivername,
                                bool privileged);
 
+void virSystemdNotifyStartup(void);
+
 #endif /* __VIR_SYSTEMD_H__ */