- add-prometheus-metrics, adjust configure.ac, Makefile.in and add

daemon/metrics.c and daemon/metrics.h for statistics in prometheus metrics.

Makefile.in

@@ -187,9 +187,9 @@ unittcpreuse.lo unitdoq.lo unitinfra.lo
 UNITTEST_OBJ_LINK=$(UNITTEST_OBJ) worker_cb.lo $(COMMON_OBJ) $(SLDNS_OBJ) \
 $(COMPAT_OBJ)
 DAEMON_SRC=daemon/acl_list.c daemon/cachedump.c daemon/daemon.c \
-daemon/remote.c daemon/stats.c daemon/unbound.c daemon/worker.c @WIN_DAEMON_SRC@
+daemon/remote.c daemon/stats.c daemon/metrics.c daemon/unbound.c daemon/worker.c @WIN_DAEMON_SRC@
 DAEMON_OBJ=acl_list.lo cachedump.lo daemon.lo \
-shm_main.lo remote.lo stats.lo unbound.lo \
+shm_main.lo remote.lo stats.lo metrics.lo unbound.lo \
 worker.lo @WIN_DAEMON_OBJ@
 DAEMON_OBJ_LINK=$(DAEMON_OBJ) $(COMMON_OBJ_ALL_SYMBOLS) $(SLDNS_OBJ) \
 $(COMPAT_OBJ) @WIN_DAEMON_OBJ_LINK@
@@ -210,11 +210,11 @@ UBANCHOR_OBJ_LINK=$(UBANCHOR_OBJ) parseutil.lo \
 $(COMPAT_OBJ_WITHOUT_CTIME) $(SLDNS_ALLOCCHECK_EXTRA_OBJ) @WIN_UBANCHOR_OBJ_LINK@
 TESTBOUND_SRC=testcode/testbound.c testcode/testpkts.c \
 daemon/worker.c daemon/acl_list.c \
-daemon/daemon.c daemon/stats.c \
+daemon/daemon.c daemon/stats.c daemon/metrics.c \
 testcode/replay.c testcode/fake_event.c
 TESTBOUND_OBJ=testbound.lo replay.lo fake_event.lo
 TESTBOUND_OBJ_LINK=$(TESTBOUND_OBJ) testpkts.lo worker.lo acl_list.lo \
-daemon.lo stats.lo shm_main.lo $(COMMON_OBJ_WITHOUT_NETCALL) ub_event.lo $(SLDNS_OBJ) \
+daemon.lo stats.lo metrics.lo shm_main.lo $(COMMON_OBJ_WITHOUT_NETCALL) ub_event.lo $(SLDNS_OBJ) \
 $(COMPAT_OBJ)
 LOCKVERIFY_SRC=testcode/lock_verify.c
 LOCKVERIFY_OBJ=lock_verify.lo
@@ -721,6 +721,7 @@ depend:
 ipset.lo ipset.o: $(srcdir)/ipset/ipset.c
 doqclient.lo doqclient.o: $(srcdir)/testcode/doqclient.c
 unitdoq.lo unitdoq.o: $(srcdir)/testcode/unitdoq.c
+metrics.lo metrics.o: $(srcdir)/daemon/metrics.c
 
 # Dependencies
 dns.lo dns.o: $(srcdir)/services/cache/dns.c config.h $(srcdir)/iterator/iter_delegpt.h $(srcdir)/util/log.h \

config.h.in

@@ -237,6 +237,9 @@
 /* Define to 1 if you have the <event.h> header file. */
 #undef HAVE_EVENT_H
 
+/* Define to 1 if you have the `evhttp_free' function. */
+#undef HAVE_EVHTTP_FREE
+
 /* Define to 1 if you have the `EVP_aes_256_cbc' function. */
 #undef HAVE_EVP_AES_256_CBC
 
@@ -980,6 +983,9 @@
 /* define this to enable debug checks. */
 #undef UNBOUND_DEBUG
 
+/* Define the default metrics HTTP endpoint port. */
+#undef UNBOUND_METRICS_PORT
+
 /* Define to 1 to use cachedb support */
 #undef USE_CACHEDB
 
@@ -1027,6 +1033,10 @@
    distributions) the use of non-ephemeral ports. */
 #undef USE_LINUX_IP_LOCAL_PORT_RANGE
 
+/* Define this to expose Unbound statistics via a prometheus metrics HTTP
+   endpoint. */
+#undef USE_METRICS
+
 /* Define if you want to use internal select based events */
 #undef USE_MINI_EVENT
 

configure

@@ -22165,6 +22165,31 @@ else $as_nop
 fi
 printf "%s\n" "#define HAVE_DECL_EVSIGNAL_ASSIGN $ac_have_decl" >>confdefs.h
 
+	# prometheus metrics depend on libevent 2.0 and later, and is therefore
+	# only enabled when the required version is found and used
+
+  for ac_func in evhttp_free
+do :
+  ac_fn_c_check_func "$LINENO" "evhttp_free" "ac_cv_func_evhttp_free"
+if test "x$ac_cv_func_evhttp_free" = xyes
+then :
+  printf "%s\n" "#define HAVE_EVHTTP_FREE 1" >>confdefs.h
+
+
+printf "%s\n" "#define USE_METRICS /**/" >>confdefs.h
+
+
+printf "%s\n" "#define UNBOUND_METRICS_PORT 9100" >>confdefs.h
+
+
+else $as_nop
+
+		{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: disabling prometheus metrics" >&5
+printf "%s\n" "$as_me: disabling prometheus metrics" >&6;}
+
+fi
+
+done
         PC_LIBEVENT_DEPENDENCY="libevent"
 
 	if test -n "$BAK_LDFLAGS_SET"; then
@@ -22174,6 +22199,8 @@ else
 
 printf "%s\n" "#define USE_MINI_EVENT 1" >>confdefs.h
 
+	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: Prometheus metrics are disabled with the builtin libevent alternative" >&5
+printf "%s\n" "$as_me: Prometheus metrics are disabled with the builtin libevent alternative" >&6;}
 fi
 
 # check for libexpat

configure.ac

@@ -1498,6 +1498,14 @@ large outgoing port ranges.  ])
 #  include "event2/event.h"
 #endif
 	])
+	# prometheus metrics depend on libevent 2.0 and later, and is therefore
+	# only enabled when the required version is found and used
+	AC_CHECK_FUNCS([evhttp_free], [
+		AC_DEFINE_UNQUOTED([USE_METRICS], [], [Define this to expose Unbound statistics via a prometheus metrics HTTP endpoint.])
+		AC_DEFINE_UNQUOTED([UNBOUND_METRICS_PORT], [9100], [Define the default metrics HTTP endpoint port.])
+	], [
+		AC_MSG_NOTICE([disabling prometheus metrics])
+	])
         PC_LIBEVENT_DEPENDENCY="libevent"
         AC_SUBST(PC_LIBEVENT_DEPENDENCY)
 	if test -n "$BAK_LDFLAGS_SET"; then
@@ -1505,6 +1513,7 @@ large outgoing port ranges.  ])
 	fi
 else
 	AC_DEFINE(USE_MINI_EVENT, 1, [Define if you want to use internal select based events])
+	AC_MSG_NOTICE([Prometheus metrics are disabled with the builtin libevent alternative])
 fi
 
 # check for libexpat

daemon/metrics.c

@@ -0,0 +1,46 @@
+/*
+ * daemon/metrics.c - prometheus metrics output.
+ *
+ * Copyright (c) 2026, NLnet Labs. All rights reserved.
+ *
+ * This software is open source.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of the NLNET LABS nor the names of its contributors may
+ * be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * \file
+ *
+ * The statistics output provides metrics to prometheus.
+ */
+#include "config.h"
+#include "daemon/metrics.h"
+
+#ifdef USE_METRICS
+
+#endif /* USE_METRICS */

daemon/metrics.h

@@ -0,0 +1,45 @@
+/*
+ * daemon/metrics.h - prometheus metrics output.
+ *
+ * Copyright (c) 2026, NLnet Labs. All rights reserved.
+ *
+ * This software is open source.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of the NLNET LABS nor the names of its contributors may
+ * be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * \file
+ *
+ * The statistics output provides metrics to prometheus.
+ */
+
+#ifndef DAEMON_METRICS_H
+#define DAEMON_METRICS_H
+
+#endif /* DAEMON_METRICS_H */