Enable compilation of the load balancer as a module

To compile the balancer as a slapd module, pass --enable-balancer=mod to ./configure
Use --enable-balancer(=yes) to compile as standalone server.

configure.ac

@@ -414,7 +414,8 @@ dnl ----------------------------------------------------------------
 dnl BALANCER OPTIONS
 AC_ARG_ENABLE(balanceroptions,[
 LLOADD (Load Balancer Daemon) Options:])
-OL_ARG_ENABLE(balancer,[  --enable-balancer	  enable building load balancer], auto)dnl
+OL_ARG_ENABLE(balancer, [AS_HELP_STRING([--enable-balancer], [enable load balancer])],
+	no, [no yes mod])
 
 dnl ----------------------------------------------------------------
 AC_ARG_ENABLE(xxliboptions,[
@@ -445,13 +446,18 @@ if test $ol_enable_slapd = no ; then
 			eval "ol_enable_$i=no"
 		fi
 	done
+
+	if test $ol_enable_balancer = mod ; then
+		AC_MSG_WARN([slapd disabled, ignoring --enable-balancer=mod argument])
+		ol_enable_balancer=no
+	fi
 else
 	dnl If slapd enabled and loadable module support disabled
 	dnl then require at least one built-in backend
 
 	if test $ol_enable_modules = no; then
 
-		for i in backends overlays $Backends $Overlays; do
+		for i in backends overlays balancer $Backends $Overlays; do
 			eval "ol_tmp=\$ol_enable_$i"
 			if test -n "$ol_tmp" && test "$ol_tmp" = mod ; then
 				AC_MSG_ERROR([--enable-$i=mod requires --enable-modules])
@@ -487,7 +493,7 @@ if test $ol_enable_modules = yes ; then
 	ol_enable_dynamic=yes
 fi
 
-if test $ol_enable_balancer = yes ; then
+if test $ol_enable_balancer != no ; then
 	dnl Load Balancer was specifically enabled
 	if test $ol_with_threads = no ; then
 		AC_MSG_ERROR([Load balancer requires threads])
@@ -524,6 +530,7 @@ CLIENT_LIBS=
 
 SLAPD_LIBS=
 BALANCER_LIBS=
+BALANCER_INCLUDE=
 
 BUILD_SLAPD=no
 BUILD_BALANCER=no
@@ -2967,8 +2974,14 @@ fi
 if test "$ol_enable_balancer" != no \
 		-a "$ol_with_threads" != no \
 		-a "$have_libevent" = yes ; then
+	if test "$ol_enable_balancer" = mod; then
+		BALANCER_INCLUDE=Makefile.module
+		BUILD_BALANCER=mod
+	else
+		BALANCER_INCLUDE=Makefile.server
 		BUILD_BALANCER=yes
 	fi
+fi
 
 if test "$ol_enable_slapi" != no ; then
 	AC_DEFINE(ENABLE_SLAPI,1,[define to enable slapi library])
@@ -3088,6 +3101,8 @@ AC_SUBST(SLAPD_SQL_INCLUDES)
 AC_SUBST(WT_INCS)
 AC_SUBST(WT_LIBS)
 
+AC_SUBST(BALANCER_INCLUDE)
+
 dnl ----------------------------------------------------------------
 dnl final help output
 AC_ARG_WITH(xxinstall,[
@@ -3134,7 +3149,9 @@ AC_CONFIG_FILES([Makefile:build/top.mk:Makefile.in:build/dir.mk]
 [servers/slapd/shell-backends/Makefile:build/top.mk:servers/slapd/shell-backends/Makefile.in:build/srv.mk]
 [servers/slapd/slapi/Makefile:build/top.mk:servers/slapd/slapi/Makefile.in:build/lib.mk:build/lib-shared.mk]
 [servers/slapd/overlays/Makefile:build/top.mk:servers/slapd/overlays/Makefile.in:build/lib.mk]
-[servers/lloadd/Makefile:build/top.mk:servers/lloadd/Makefile.in:build/srv.mk]
+[servers/lloadd/Makefile:build/top.mk:servers/lloadd/Makefile.in]
+[servers/lloadd/Makefile.server:servers/lloadd/Makefile_server.in:build/srv.mk]
+[servers/lloadd/Makefile.module:servers/lloadd/Makefile_module.in:build/mod.mk]
 [tests/Makefile:build/top.mk:tests/Makefile.in:build/dir.mk]
 [tests/run]
 [tests/progs/Makefile:build/top.mk:tests/progs/Makefile.in:build/rules.mk])

doc/man/man8/lloadd.8

@@ -215,6 +215,41 @@ This allows one to specifically query the SLP DAs for LDAP servers holding the
 .I production
 tree in case multiple trees are available.
 .RE
+
+.SH RELATION TO SLAPD(8)
+.B Lloadd
+can be compiled as a
+.B slapd
+loadable module. In that case, it can be loaded as such:
+.LP
+.nf
+.ft tt
+	moduleload path/to/lloadd.la lloadd.conf "listening URLs"
+.ft
+.fi
+
+This enables
+.B lloadd
+to provide additional features through the host slapd process like access to
+run-time statistics in
+.B cn=monitor
+and dynamic configuration from
+.BR cn=config .
+
+The listening sockets specified will be under direct control of
+.B lloadd
+and need to be different from the sockets slapd is configured to listen on.
+Clients connecting to these are completely separate from regular LDAP clients
+connecting to the usual
+.B slapd
+sockets -
+.B lloadd
+clients have no access to slapd databases, similarly,
+.B slapd
+client traffic does not propagate to the
+.B lloadd
+backend servers in any way.
+
 .SH EXAMPLES
 To start
 .I lloadd
@@ -237,9 +272,22 @@ on voluminous debugging which will be printed on standard error, type:
 	LIBEXECDIR/lloadd \-f /var/tmp/lloadd.conf \-d 255
 .ft
 .fi
+.LP
+To start
+.B lloadd
+as a module inside a slapd process listening on ldap://:1389 and ldaps://,
+put the following in your slapd.conf (or its equivalent in cn=config):
+.LP
+.nf
+.ft tt
+	moduleload lloadd.la /var/tmp/lloadd.conf "ldap://:1389 ldaps://"
+.ft
+.fi
 .SH "SEE ALSO"
 .BR ldap (3),
 .BR lloadd.conf (5),
+.BR slapd-config (5),
+.BR slapd-monitor (5),
 .BR slapd (8).
 .LP
 "OpenLDAP Administrator's Guide" (http://www.OpenLDAP.org/doc/admin/)

servers/lloadd/Makefile.in

@@ -13,28 +13,21 @@
 ## top-level directory of the distribution or, alternatively, at
 ## <http://www.OpenLDAP.org/license.html>.
 
-PROGRAMS = lloadd
-XPROGRAMS = slloadd
 
 XSRCS	= version.c
 
 NT_SRCS = nt_svc.c
 NT_OBJS = nt_svc.o ../../libraries/liblutil/slapdmsg.res
 
-SRCS	= main.c globals.c backend.c bind.c config.c connection.c client.c \
+SRCS	= backend.c bind.c config.c connection.c client.c \
-		  daemon.c ch_malloc.c init.c operation.c user.c sl_malloc.c \
+		  daemon.c extended.c operation.c \
-		  upstream.c value.c libevent_support.c extended.c \
+		  upstream.c libevent_support.c \
 		  $(@PLAT@_SRCS)
 
-OBJS	= $(patsubst %.c,%.o,$(SRCS)) $(@PLAT@_OBJS)
 
-LDAP_INCDIR= ../../include -I$(srcdir)
+LDAP_INCDIR= ../../include -I$(srcdir) -I$(srcdir)/../slapd
 LDAP_LIBDIR= ../../libraries
 
-BUILD_OPT = "--enable-balancer"
-BUILD_SRV = @BUILD_BALANCER@
-
-all-local-srv: 	$(PROGRAMS)
 
 # $(LTHREAD_LIBS) must be last!
 XLIBS = $(LLOADD_L)
@@ -50,25 +43,6 @@ UNIX_OBJECTS = $(OBJS) version.o
 LLOADD_DEPENDS = $(@PLAT@_DEPENDS)
 LLOADD_OBJECTS = $(@PLAT@_OBJECTS)
 
-lloadd:	$(LLOADD_DEPENDS) version.o
+include @BALANCER_INCLUDE@
-	$(LTLINK) -o $@ $(OBJS) version.o $(LIBS)
 
-slloadd:	version.o
-	$(LTLINK) -static -o $@ $(OBJS) version.o $(LIBS)
-
-version.c: Makefile
-	@-$(RM) $@
-	$(MKVERSION) -s -n Versionstr lloadd > $@
-
-version.o: version.c $(OBJS) $(LLOADD_L)
-
-install-local-srv: FORCE
-	-$(MKDIR) $(DESTDIR)$(libexecdir)
-	@-$(INSTALL) -m 700 -d $(DESTDIR)$(localstatedir)/openldap-lloadd
-	@(								\
-	    for prg in $(PROGRAMS); do					\
-		$(LTINSTALL) $(INSTALLFLAGS) $(STRIP) -m 755 $$prg$(EXEEXT)	\
-		    $(DESTDIR)$(libexecdir);				\
-	    done							\
-	)
 

servers/lloadd/Makefile_module.in

@@ -0,0 +1,45 @@
+# Makefile.in for Load Balancer
+# $OpenLDAP$
+## This work is part of OpenLDAP Software <http://www.openldap.org/>.
+##
+## Copyright 1998-2020 The OpenLDAP Foundation.
+## All rights reserved.
+##
+## Redistribution and use in source and binary forms, with or without
+## modification, are permitted only as authorized by the OpenLDAP
+## Public License.
+##
+## A copy of this license is available in the file LICENSE in the
+## top-level directory of the distribution or, alternatively, at
+## <http://www.OpenLDAP.org/license.html>.
+
+
+XSRCS	= version.c
+
+NT_SRCS = nt_svc.c
+NT_OBJS = nt_svc.o ../../libraries/liblutil/slapdmsg.res
+
+SRCS	+= module_init.c
+
+OBJS	= $(patsubst %.c,%.lo,$(SRCS)) $(@PLAT@_OBJS)
+
+BUILD_OPT = "--enable-balancer=mod"
+BUILD_MOD = @BUILD_BALANCER@
+
+LIBBASE=lloadd
+
+# $(LTHREAD_LIBS) must be last!
+XLIBS = $(LLOADD_L)
+XXLIBS = $(LLOADD_LIBS) $(SECURITY_LIBS) $(LUTIL_LIBS)
+XXXLIBS = $(LTHREAD_LIBS)
+
+NT_DEPENDS = slapd.exp
+NT_OBJECTS = slapd.exp symdummy.o $(LLOADD_OBJS) version.o
+
+UNIX_DEPENDS = version.o $(LLOADD_L)
+UNIX_OBJECTS = $(OBJS) version.o
+
+LLOADD_DEPENDS = $(@PLAT@_DEPENDS)
+LLOADD_OBJECTS = $(@PLAT@_OBJECTS)
+LINK_LIBS=$(LLOADD_LIBS)
+MOD_DEFS = -DSLAPD_IMPORT -DBALANCER_MODULE

servers/lloadd/Makefile_server.in

@@ -0,0 +1,69 @@
+# Makefile.in for Load Balancer
+# $OpenLDAP$
+## This work is part of OpenLDAP Software <http://www.openldap.org/>.
+##
+## Copyright 1998-2020 The OpenLDAP Foundation.
+## All rights reserved.
+##
+## Redistribution and use in source and binary forms, with or without
+## modification, are permitted only as authorized by the OpenLDAP
+## Public License.
+##
+## A copy of this license is available in the file LICENSE in the
+## top-level directory of the distribution or, alternatively, at
+## <http://www.OpenLDAP.org/license.html>.
+
+PROGRAMS = lloadd
+XPROGRAMS = slloadd
+
+XSRCS	= version.c
+
+NT_SRCS = nt_svc.c
+NT_OBJS = nt_svc.o ../../libraries/liblutil/slapdmsg.res
+
+SRCS	+= main.c init.c value.c \
+		  ch_malloc.c sl_malloc.c user.c
+
+OBJS	= $(patsubst %.c,%.o,$(SRCS)) $(@PLAT@_OBJS)
+
+BUILD_OPT = "--enable-balancer"
+BUILD_SRV = @BUILD_BALANCER@
+
+all-local-srv: 	$(PROGRAMS)
+
+# $(LTHREAD_LIBS) must be last!
+XLIBS = $(LLOADD_L)
+XXLIBS = $(LLOADD_LIBS) $(SECURITY_LIBS) $(LUTIL_LIBS)
+XXXLIBS = $(LTHREAD_LIBS)
+
+NT_DEPENDS = slapd.exp
+NT_OBJECTS = slapd.exp symdummy.o $(LLOADD_OBJS) version.o
+
+UNIX_DEPENDS = version.o $(LLOADD_L)
+UNIX_OBJECTS = $(OBJS) version.o
+
+LLOADD_DEPENDS = $(@PLAT@_DEPENDS)
+LLOADD_OBJECTS = $(@PLAT@_OBJECTS)
+
+
+lloadd:	$(LLOADD_DEPENDS) version.o
+	$(LTLINK) -o $@ $(OBJS) version.o $(LIBS)
+
+slloadd:	version.o
+	$(LTLINK) -static -o $@ $(OBJS) version.o $(LIBS)
+
+version.c: Makefile
+	@-$(RM) $@
+	$(MKVERSION) -s -n Versionstr lloadd > $@
+
+version.o: version.c $(OBJS) $(LLOADD_L)
+
+install-local-srv: FORCE
+	-$(MKDIR) $(DESTDIR)$(libexecdir)
+	@-$(INSTALL) -m 700 -d $(DESTDIR)$(localstatedir)/openldap-lloadd
+	@(								\
+	    for prg in $(PROGRAMS); do					\
+		$(LTINSTALL) $(INSTALLFLAGS) $(STRIP) -m 755 $$prg$(EXEEXT)	\
+		    $(DESTDIR)$(libexecdir);				\
+	    done							\
+	)

servers/lloadd/libevent_support.c

@@ -150,9 +150,13 @@ lload_libevent_init( void )
         lload_libevent_cond_timedwait
     };
 
+#ifndef BALANCER_MODULE
+    /* only necessary if lload is a server, slapd already calls
+     * ldap_pvt_thread_initialize() */
     if ( ldap_pvt_thread_initialize() ) {
         return -1;
     }
+#endif
 
     evthread_set_lock_callbacks( &cbs );
     evthread_set_condition_callbacks( &cond_cbs );

servers/lloadd/module_init.c

@@ -0,0 +1,110 @@
+/* module_init.c - module initialization functions */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 1998-2020 The OpenLDAP Foundation.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* Portions Copyright (c) 1995 Regents of the University of Michigan.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms are permitted
+ * provided that this notice is preserved and that due credit is given
+ * to the University of Michigan at Ann Arbor. The name of the University
+ * may not be used to endorse or promote products derived from this
+ * software without specific prior written permission. This software
+ * is provided ``as is'' without express or implied warranty.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+
+#include <ac/socket.h>
+#include <ac/string.h>
+#include <ac/time.h>
+
+#include "../servers/slapd/slap.h"
+
+#include "lload.h"
+#include "lber_pvt.h"
+
+#include "ldap_rq.h"
+
+int
+lload_start_daemon()
+{
+    struct event_base *daemon_base = event_base_new();
+    int rc = 0, i;
+    if ( !daemon_base ) {
+        Debug( LDAP_DEBUG_ANY, "lload_start_daemon: "
+                "main event base allocation failed\n" );
+        rc = 1;
+        return rc;
+    }
+
+    rc = lloadd_daemon( daemon_base );
+    return rc;
+}
+
+/* from init.c */
+int
+lload_conn_pool_init()
+{
+    int rc = 0;
+
+    ldap_pvt_thread_mutex_init( &backend_mutex );
+    ldap_pvt_thread_mutex_init( &clients_mutex );
+
+    lload_exop_init();
+    Debug( LDAP_DEBUG_TRACE, "lload_conn_pool_init: "
+            "mutexes initialized.\n" );
+    return rc;
+}
+
+void *
+lload_module_start_daemon( void *ctx, void *arg )
+{
+    lload_start_daemon();
+    return NULL;
+}
+
+int
+init_module( int argc, char *argv[] )
+{
+    if ( slapMode & SLAP_TOOL_MODE ) {
+        return 0;
+    }
+    if ( lload_libevent_init() ) {
+        return -1;
+    }
+    global_host = ldap_pvt_get_fqdn( NULL );
+#ifdef HAVE_TLS
+    if ( ldap_create( &lload_tls_backend_ld ) ) {
+        return -1;
+    }
+#endif /* HAVE_TLS */
+
+    if ( lloadd_daemon_init( argv[1] ) != 0 ) {
+        return -1;
+    }
+    lload_conn_pool_init();
+
+    if ( lload_read_config( argv[0], NULL ) != 0 ) {
+        return -1;
+    }
+
+    ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
+    ldap_pvt_runqueue_insert( &slapd_rq, 0, lload_module_start_daemon, NULL,
+            "lload_module_start_daemon", "lloadd" );
+    ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
+    return 0;
+}

tests/Makefile.in

@@ -18,6 +18,7 @@ SUBDIRS= progs
 
 BUILD_MDB=@BUILD_MDB@
 BUILD_SQL=@BUILD_SQL@
+BUILD_SLAPD=@BUILD_SLAPD@
 BUILD_BALANCER=@BUILD_BALANCER@
 
 # test primary backends (default)
@@ -54,7 +55,12 @@ lloadd test-lloadd: lloadd-$(BUILD_BALANCER)
 lloadd-no:
 	@echo "run configure with --enable-balancer to run the Load Balancer tests"
 
-lloadd-yes: FORCE
+lloadd-yes: lloadd-slapd-$(BUILD_SLAPD)
+
+lloadd-slapd-no:
+	@echo "run configure with --enable-slapd to run the Load Balancer tests"
+
+lloadd-slapd-yes: FORCE
 	@echo "Initiating LDAP tests for the Load Balancer..."
 	@$(RUN) lloadd-all