[PATCH] better systemd integration

From 607323c95ca62d74668992219569c7cff470b63d Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Tue, 17 Nov 2015 06:47:18 -0500
Subject: [PATCH 1/3] Improve error reporting when location specified by
 postgres -D does not exist

Previously, the first error seen would be that postgresql.conf does not
exist.  But for the case where the whole directory does not exist, give
an error message about that, together with a hint for how to create one.
---
 src/backend/utils/misc/guc.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 38ba82f..b8d34b5 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -4463,6 +4463,17 @@ SelectConfigFiles(const char *userDoption, const char *progname)
 	else
 		configdir = make_absolute_path(getenv("PGDATA"));
 
+	if (configdir && stat(configdir, &stat_buf) != 0)
+	{
+		write_stderr("%s: could not access \"%s\": %s\n",
+					 progname,
+					 configdir,
+					 strerror(errno));
+		if (errno == ENOENT)
+			write_stderr("Run initdb or pg_basebackup to initialize a PostgreSQL data directory.\n");
+		return false;
+	}
+
 	/*
 	 * Find the configuration file: if config_file was specified on the
 	 * command line, use it, else use configdir/postgresql.conf.  In any case
@@ -4498,7 +4509,7 @@ SelectConfigFiles(const char *userDoption, const char *progname)
 	 */
 	if (stat(ConfigFileName, &stat_buf) != 0)
 	{
-		write_stderr("%s cannot access the server configuration file \"%s\": %s\n",
+		write_stderr("%s: could not access the server configuration file \"%s\": %s\n",
 					 progname, ConfigFileName, strerror(errno));
 		free(configdir);
 		return false;
-- 
2.7.0

From 339836d39d8566ed794f6e1d56384fd93073d5bf Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Tue, 17 Nov 2015 06:46:17 -0500
Subject: [PATCH 2/3] Add support for systemd service notifications

Insert sd_notify() calls at server start and stop for integration with
systemd.  This allows the use of systemd service units of type "notify",
which greatly simplifies the systemd configuration.
---
 configure                           | 38 +++++++++++++++++++++++++++++++++++++
 configure.in                        |  9 +++++++++
 doc/src/sgml/installation.sgml      | 16 ++++++++++++++++
 doc/src/sgml/runtime.sgml           | 24 +++++++++++++++++++++++
 src/Makefile.global.in              |  1 +
 src/backend/Makefile                |  4 ++++
 src/backend/postmaster/postmaster.c | 21 ++++++++++++++++++++
 src/include/pg_config.h.in          |  3 +++
 8 files changed, 116 insertions(+)

diff --git a/configure b/configure
index 3dd1b15..5c2e767 100755
--- a/configure
+++ b/configure
@@ -709,6 +709,7 @@ with_libxml
 XML2_CONFIG
 UUID_EXTRA_OBJS
 with_uuid
+with_systemd
 with_selinux
 with_openssl
 krb_srvtab
@@ -830,6 +831,7 @@ with_ldap
 with_bonjour
 with_openssl
 with_selinux
+with_systemd
 with_readline
 with_libedit_preferred
 with_uuid
@@ -1518,6 +1520,7 @@ Optional Packages:
   --with-bonjour          build with Bonjour support
   --with-openssl          build with OpenSSL support
   --with-selinux          build with SELinux support
+  --with-systemd          build with systemd support
   --without-readline      do not use GNU Readline nor BSD Libedit for editing
   --with-libedit-preferred
                           prefer BSD Libedit over GNU Readline
@@ -5695,6 +5698,41 @@ fi
 $as_echo "$with_selinux" >&6; }
 
 #
+# Systemd
+#
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to build with systemd support" >&5
+$as_echo_n "checking whether to build with systemd support... " >&6; }
+
+
+
+# Check whether --with-systemd was given.
+if test "${with_systemd+set}" = set; then :
+  withval=$with_systemd;
+  case $withval in
+    yes)
+
+$as_echo "#define USE_SYSTEMD 1" >>confdefs.h
+
+      ;;
+    no)
+      :
+      ;;
+    *)
+      as_fn_error $? "no argument expected for --with-systemd option" "$LINENO" 5
+      ;;
+  esac
+
+else
+  with_systemd=no
+
+fi
+
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_systemd" >&5
+$as_echo "$with_systemd" >&6; }
+
+#
 # Readline
 #
 
diff --git a/configure.in b/configure.in
index 9398482..20d9fe1 100644
--- a/configure.in
+++ b/configure.in
@@ -700,6 +700,15 @@ AC_SUBST(with_selinux)
 AC_MSG_RESULT([$with_selinux])
 
 #
+# Systemd
+#
+AC_MSG_CHECKING([whether to build with systemd support])
+PGAC_ARG_BOOL(with, systemd, no, [build with systemd support],
+              [AC_DEFINE([USE_SYSTEMD], 1, [Define to build with systemd support. (--with-systemd)])])
+AC_SUBST(with_systemd)
+AC_MSG_RESULT([$with_systemd])
+
+#
 # Readline
 #
 PGAC_ARG_BOOL(with, readline, yes,
diff --git a/doc/src/sgml/installation.sgml b/doc/src/sgml/installation.sgml
index 8964834..7b6a389 100644
--- a/doc/src/sgml/installation.sgml
+++ b/doc/src/sgml/installation.sgml
@@ -813,6 +813,22 @@ <title>Configuration</title>
       </varlistentry>
 
       <varlistentry>
+       <term><option>--with-systemd</option></term>
+       <listitem>
+        <para>
+         Build with support
+         for <application>systemd</application><indexterm><primary>systemd</primary></indexterm>
+         service notifications.  This improves integration if the server binary
+         is started under <application>systemd</application> but has no impact
+         otherwise; see <xref linkend="server-start"> for more
+         information.  <application>libsystemd</application> and the
+         associated header files need to be installed to be able to use this
+         option.
+        </para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
        <term><option>--without-readline</option></term>
        <listitem>
         <para>
diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index cda05f5..58b8838 100644
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -369,6 +369,30 @@ <title>Starting the Database Server</title>
       <filename>contrib/start-scripts/linux</filename> in the
       <productname>PostgreSQL</productname> source distribution.
      </para>
+
+     <para>
+      When using <application>systemd</application>, you can use the following
+      service unit file (e.g.,
+      at <filename>/etc/systemd/system/postgresql.service</filename>):<indexterm><primary>systemd</primary></indexterm>
+<programlisting>
+[Unit]
+Description=PostgreSQL database server
+Documentation=man:postgres(1)
+
+[Service]
+Type=notify
+User=postgres
+ExecStart=/usr/local/pgsql/bin/postgres -D /usr/local/pgsql/data
+ExecReload=/bin/kill -HUP $MAINPID
+KillMode=mixed
+KillSignal=SIGINT
+
+[Install]
+WantedBy=multi-user.target
+</programlisting>
+      Using <literal>Type=notify</literal> requires that the server binary was
+      built with <literal>configure --with-systemd</literal>.
+     </para>
     </listitem>
 
     <listitem>
diff --git a/src/Makefile.global.in b/src/Makefile.global.in
index 51f4797..e94d6a5 100644
--- a/src/Makefile.global.in
+++ b/src/Makefile.global.in
@@ -184,6 +184,7 @@ with_python	= @with_python@
 with_tcl	= @with_tcl@
 with_openssl	= @with_openssl@
 with_selinux	= @with_selinux@
+with_systemd	= @with_systemd@
 with_libxml	= @with_libxml@
 with_libxslt	= @with_libxslt@
 with_system_tzdata = @with_system_tzdata@
diff --git a/src/backend/Makefile b/src/backend/Makefile
index d4db8ff..b3d5e2e 100644
--- a/src/backend/Makefile
+++ b/src/backend/Makefile
@@ -45,6 +45,10 @@ LIBS := $(filter-out -lpgport -lpgcommon, $(LIBS)) $(LDAP_LIBS_BE)
 # The backend doesn't need everything that's in LIBS, however
 LIBS := $(filter-out -lz -lreadline -ledit -ltermcap -lncurses -lcurses, $(LIBS))
 
+ifeq ($(with_systemd),yes)
+LIBS += -lsystemd
+endif
+
 ##########################################################################
 
 all: submake-libpgport submake-schemapg postgres $(POSTGRES_IMP)
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 9aaed5b..2e7f1d7 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -87,6 +87,10 @@
 #include <dns_sd.h>
 #endif
 
+#ifdef USE_SYSTEMD
+#include <systemd/sd-daemon.h>
+#endif
+
 #ifdef HAVE_PTHREAD_IS_THREADED_NP
 #include <pthread.h>
 #endif
@@ -2533,6 +2537,9 @@ pmdie(SIGNAL_ARGS)
 			Shutdown = SmartShutdown;
 			ereport(LOG,
 					(errmsg("received smart shutdown request")));
+#ifdef USE_SYSTEMD
+			sd_notify(0, "STOPPING=1");
+#endif
 
 			if (pmState == PM_RUN || pmState == PM_RECOVERY ||
 				pmState == PM_HOT_STANDBY || pmState == PM_STARTUP)
@@ -2585,6 +2592,9 @@ pmdie(SIGNAL_ARGS)
 			Shutdown = FastShutdown;
 			ereport(LOG,
 					(errmsg("received fast shutdown request")));
+#ifdef USE_SYSTEMD
+			sd_notify(0, "STOPPING=1");
+#endif
 
 			if (StartupPID != 0)
 				signal_child(StartupPID, SIGTERM);
@@ -2645,6 +2655,9 @@ pmdie(SIGNAL_ARGS)
 			Shutdown = ImmediateShutdown;
 			ereport(LOG,
 					(errmsg("received immediate shutdown request")));
+#ifdef USE_SYSTEMD
+			sd_notify(0, "STOPPING=1");
+#endif
 
 			TerminateChildren(SIGQUIT);
 			pmState = PM_WAIT_BACKENDS;
@@ -2787,6 +2800,10 @@ reaper(SIGNAL_ARGS)
 			ereport(LOG,
 				 (errmsg("database system is ready to accept connections")));
 
+#ifdef USE_SYSTEMD
+			sd_notify(0, "READY=1");
+#endif
+
 			continue;
 		}
 
@@ -4930,6 +4947,10 @@ sigusr1_handler(SIGNAL_ARGS)
 		ereport(LOG,
 		(errmsg("database system is ready to accept read only connections")));
 
+#ifdef USE_SYSTEMD
+		sd_notify(0, "READY=1");
+#endif
+
 		pmState = PM_HOT_STANDBY;
 		/* Some workers may be scheduled to start now */
 		StartWorkerNeeded = true;
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 16a272e..b3ceea5 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -833,6 +833,9 @@
 /* Define to 1 to use Intel SSSE 4.2 CRC instructions with a runtime check. */
 #undef USE_SSE42_CRC32C_WITH_RUNTIME_CHECK
 
+/* Define to build with systemd support. (--with-systemd) */
+#undef USE_SYSTEMD
+
 /* Define to select SysV-style semaphores. */
 #undef USE_SYSV_SEMAPHORES
 
-- 
2.7.0

From 607323c95ca62d74668992219569c7cff470b63d Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Tue, 17 Nov 2015 06:47:18 -0500
Subject: [PATCH 1/3] Improve error reporting when location specified by
 postgres -D does not exist

Previously, the first error seen would be that postgresql.conf does not
exist.  But for the case where the whole directory does not exist, give
an error message about that, together with a hint for how to create one.
---
 src/backend/utils/misc/guc.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 38ba82f..b8d34b5 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -4463,6 +4463,17 @@ SelectConfigFiles(const char *userDoption, const char *progname)
 	else
 		configdir = make_absolute_path(getenv("PGDATA"));
 
+	if (configdir && stat(configdir, &stat_buf) != 0)
+	{
+		write_stderr("%s: could not access \"%s\": %s\n",
+					 progname,
+					 configdir,
+					 strerror(errno));
+		if (errno == ENOENT)
+			write_stderr("Run initdb or pg_basebackup to initialize a PostgreSQL data directory.\n");
+		return false;
+	}
+
 	/*
 	 * Find the configuration file: if config_file was specified on the
 	 * command line, use it, else use configdir/postgresql.conf.  In any case
@@ -4498,7 +4509,7 @@ SelectConfigFiles(const char *userDoption, const char *progname)
 	 */
 	if (stat(ConfigFileName, &stat_buf) != 0)
 	{
-		write_stderr("%s cannot access the server configuration file \"%s\": %s\n",
+		write_stderr("%s: could not access the server configuration file \"%s\": %s\n",
 					 progname, ConfigFileName, strerror(errno));
 		free(configdir);
 		return false;
-- 
2.7.0

From 8a2156bd3add4c8427d216df5757554a421573e7 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Tue, 17 Nov 2015 06:46:17 -0500
Subject: [PATCH 2/3] Add support for systemd service notifications

Insert sd_notify() calls at server start and stop for integration with
systemd.  This allows the use of systemd service units of type "notify",
which greatly simplifies the systemd configuration.
---
 configure                           | 49 +++++++++++++++++++++++++++++++++++++
 configure.in                        | 13 ++++++++++
 doc/src/sgml/installation.sgml      | 16 ++++++++++++
 doc/src/sgml/runtime.sgml           | 24 ++++++++++++++++++
 src/Makefile.global.in              |  1 +
 src/backend/Makefile                |  4 +++
 src/backend/postmaster/postmaster.c | 21 ++++++++++++++++
 src/include/pg_config.h.in          |  3 +++
 8 files changed, 131 insertions(+)

diff --git a/configure b/configure
index 3dd1b15..b3f3abe 100755
--- a/configure
+++ b/configure
@@ -709,6 +709,7 @@ with_libxml
 XML2_CONFIG
 UUID_EXTRA_OBJS
 with_uuid
+with_systemd
 with_selinux
 with_openssl
 krb_srvtab
@@ -830,6 +831,7 @@ with_ldap
 with_bonjour
 with_openssl
 with_selinux
+with_systemd
 with_readline
 with_libedit_preferred
 with_uuid
@@ -1518,6 +1520,7 @@ Optional Packages:
   --with-bonjour          build with Bonjour support
   --with-openssl          build with OpenSSL support
   --with-selinux          build with SELinux support
+  --with-systemd          build with systemd support
   --without-readline      do not use GNU Readline nor BSD Libedit for editing
   --with-libedit-preferred
                           prefer BSD Libedit over GNU Readline
@@ -5695,6 +5698,41 @@ fi
 $as_echo "$with_selinux" >&6; }
 
 #
+# Systemd
+#
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to build with systemd support" >&5
+$as_echo_n "checking whether to build with systemd support... " >&6; }
+
+
+
+# Check whether --with-systemd was given.
+if test "${with_systemd+set}" = set; then :
+  withval=$with_systemd;
+  case $withval in
+    yes)
+
+$as_echo "#define USE_SYSTEMD 1" >>confdefs.h
+
+      ;;
+    no)
+      :
+      ;;
+    *)
+      as_fn_error $? "no argument expected for --with-systemd option" "$LINENO" 5
+      ;;
+  esac
+
+else
+  with_systemd=no
+
+fi
+
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_systemd" >&5
+$as_echo "$with_systemd" >&6; }
+
+#
 # Readline
 #
 
@@ -10475,6 +10513,17 @@ done
 
 fi
 
+if test "$with_systemd" = yes ; then
+  ac_fn_c_check_header_mongrel "$LINENO" "systemd/sd-daemon.h" "ac_cv_header_systemd_sd_daemon_h" "$ac_includes_default"
+if test "x$ac_cv_header_systemd_sd_daemon_h" = xyes; then :
+
+else
+  as_fn_error $? "header file <systemd/sd-daemon.h> is required for systemd support" "$LINENO" 5
+fi
+
+
+fi
+
 if test "$with_libxml" = yes ; then
   ac_fn_c_check_header_mongrel "$LINENO" "libxml/parser.h" "ac_cv_header_libxml_parser_h" "$ac_includes_default"
 if test "x$ac_cv_header_libxml_parser_h" = xyes; then :
diff --git a/configure.in b/configure.in
index 9398482..0bd90d7 100644
--- a/configure.in
+++ b/configure.in
@@ -700,6 +700,15 @@ AC_SUBST(with_selinux)
 AC_MSG_RESULT([$with_selinux])
 
 #
+# Systemd
+#
+AC_MSG_CHECKING([whether to build with systemd support])
+PGAC_ARG_BOOL(with, systemd, no, [build with systemd support],
+              [AC_DEFINE([USE_SYSTEMD], 1, [Define to build with systemd support. (--with-systemd)])])
+AC_SUBST(with_systemd)
+AC_MSG_RESULT([$with_systemd])
+
+#
 # Readline
 #
 PGAC_ARG_BOOL(with, readline, yes,
@@ -1249,6 +1258,10 @@ if test "$with_pam" = yes ; then
                                      [AC_MSG_ERROR([header file <security/pam_appl.h> or <pam/pam_appl.h> is required for PAM.])])])
 fi
 
+if test "$with_systemd" = yes ; then
+  AC_CHECK_HEADER(systemd/sd-daemon.h, [], [AC_MSG_ERROR([header file <systemd/sd-daemon.h> is required for systemd support])])
+fi
+
 if test "$with_libxml" = yes ; then
   AC_CHECK_HEADER(libxml/parser.h, [], [AC_MSG_ERROR([header file <libxml/parser.h> is required for XML support])])
 fi
diff --git a/doc/src/sgml/installation.sgml b/doc/src/sgml/installation.sgml
index 8964834..7b6a389 100644
--- a/doc/src/sgml/installation.sgml
+++ b/doc/src/sgml/installation.sgml
@@ -813,6 +813,22 @@ <title>Configuration</title>
       </varlistentry>
 
       <varlistentry>
+       <term><option>--with-systemd</option></term>
+       <listitem>
+        <para>
+         Build with support
+         for <application>systemd</application><indexterm><primary>systemd</primary></indexterm>
+         service notifications.  This improves integration if the server binary
+         is started under <application>systemd</application> but has no impact
+         otherwise; see <xref linkend="server-start"> for more
+         information.  <application>libsystemd</application> and the
+         associated header files need to be installed to be able to use this
+         option.
+        </para>
+       </listitem>
+      </varlistentry>
+
+      <varlistentry>
        <term><option>--without-readline</option></term>
        <listitem>
         <para>
diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index cda05f5..58b8838 100644
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -369,6 +369,30 @@ <title>Starting the Database Server</title>
       <filename>contrib/start-scripts/linux</filename> in the
       <productname>PostgreSQL</productname> source distribution.
      </para>
+
+     <para>
+      When using <application>systemd</application>, you can use the following
+      service unit file (e.g.,
+      at <filename>/etc/systemd/system/postgresql.service</filename>):<indexterm><primary>systemd</primary></indexterm>
+<programlisting>
+[Unit]
+Description=PostgreSQL database server
+Documentation=man:postgres(1)
+
+[Service]
+Type=notify
+User=postgres
+ExecStart=/usr/local/pgsql/bin/postgres -D /usr/local/pgsql/data
+ExecReload=/bin/kill -HUP $MAINPID
+KillMode=mixed
+KillSignal=SIGINT
+
+[Install]
+WantedBy=multi-user.target
+</programlisting>
+      Using <literal>Type=notify</literal> requires that the server binary was
+      built with <literal>configure --with-systemd</literal>.
+     </para>
     </listitem>
 
     <listitem>
diff --git a/src/Makefile.global.in b/src/Makefile.global.in
index 51f4797..e94d6a5 100644
--- a/src/Makefile.global.in
+++ b/src/Makefile.global.in
@@ -184,6 +184,7 @@ with_python	= @with_python@
 with_tcl	= @with_tcl@
 with_openssl	= @with_openssl@
 with_selinux	= @with_selinux@
+with_systemd	= @with_systemd@
 with_libxml	= @with_libxml@
 with_libxslt	= @with_libxslt@
 with_system_tzdata = @with_system_tzdata@
diff --git a/src/backend/Makefile b/src/backend/Makefile
index d4db8ff..b3d5e2e 100644
--- a/src/backend/Makefile
+++ b/src/backend/Makefile
@@ -45,6 +45,10 @@ LIBS := $(filter-out -lpgport -lpgcommon, $(LIBS)) $(LDAP_LIBS_BE)
 # The backend doesn't need everything that's in LIBS, however
 LIBS := $(filter-out -lz -lreadline -ledit -ltermcap -lncurses -lcurses, $(LIBS))
 
+ifeq ($(with_systemd),yes)
+LIBS += -lsystemd
+endif
+
 ##########################################################################
 
 all: submake-libpgport submake-schemapg postgres $(POSTGRES_IMP)
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 9aaed5b..2e7f1d7 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -87,6 +87,10 @@
 #include <dns_sd.h>
 #endif
 
+#ifdef USE_SYSTEMD
+#include <systemd/sd-daemon.h>
+#endif
+
 #ifdef HAVE_PTHREAD_IS_THREADED_NP
 #include <pthread.h>
 #endif
@@ -2533,6 +2537,9 @@ pmdie(SIGNAL_ARGS)
 			Shutdown = SmartShutdown;
 			ereport(LOG,
 					(errmsg("received smart shutdown request")));
+#ifdef USE_SYSTEMD
+			sd_notify(0, "STOPPING=1");
+#endif
 
 			if (pmState == PM_RUN || pmState == PM_RECOVERY ||
 				pmState == PM_HOT_STANDBY || pmState == PM_STARTUP)
@@ -2585,6 +2592,9 @@ pmdie(SIGNAL_ARGS)
 			Shutdown = FastShutdown;
 			ereport(LOG,
 					(errmsg("received fast shutdown request")));
+#ifdef USE_SYSTEMD
+			sd_notify(0, "STOPPING=1");
+#endif
 
 			if (StartupPID != 0)
 				signal_child(StartupPID, SIGTERM);
@@ -2645,6 +2655,9 @@ pmdie(SIGNAL_ARGS)
 			Shutdown = ImmediateShutdown;
 			ereport(LOG,
 					(errmsg("received immediate shutdown request")));
+#ifdef USE_SYSTEMD
+			sd_notify(0, "STOPPING=1");
+#endif
 
 			TerminateChildren(SIGQUIT);
 			pmState = PM_WAIT_BACKENDS;
@@ -2787,6 +2800,10 @@ reaper(SIGNAL_ARGS)
 			ereport(LOG,
 				 (errmsg("database system is ready to accept connections")));
 
+#ifdef USE_SYSTEMD
+			sd_notify(0, "READY=1");
+#endif
+
 			continue;
 		}
 
@@ -4930,6 +4947,10 @@ sigusr1_handler(SIGNAL_ARGS)
 		ereport(LOG,
 		(errmsg("database system is ready to accept read only connections")));
 
+#ifdef USE_SYSTEMD
+		sd_notify(0, "READY=1");
+#endif
+
 		pmState = PM_HOT_STANDBY;
 		/* Some workers may be scheduled to start now */
 		StartWorkerNeeded = true;
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 16a272e..b3ceea5 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -833,6 +833,9 @@
 /* Define to 1 to use Intel SSSE 4.2 CRC instructions with a runtime check. */
 #undef USE_SSE42_CRC32C_WITH_RUNTIME_CHECK
 
+/* Define to build with systemd support. (--with-systemd) */
+#undef USE_SYSTEMD
+
 /* Define to select SysV-style semaphores. */
 #undef USE_SYSV_SEMAPHORES
 
-- 
2.7.0