Add NATS modules to modules-contrib

Add five community-contributed modules that integrate OpenSIPS with
NATS and JetStream:

  nats              shared connection pool and libnats loader
  event_nats        event transport over NATS subjects and JetStream
  cachedb_nats      cachedb backend on JetStream KV (usrloc, b2b)
  cachedb_nats_fts  optional full-text search for cachedb_nats
  nats_consumer     JetStream pull consumer with request/reply

The modules load libnats 3.14 or later with dlopen.  Also add Debian
and RPM packaging entries and a libnats install script.

Each module carries its unit tests as a <module>/test/ suite run by
unittests.yml (make test-<module>); the CI legs install libnats, and a
suite whose module was not built is skipped.  The end-to-end checks are
SIPssert scenarios for sipssert-opensips-tests.

Author: NormB

.github/workflows/unittests.yml

@@ -127,6 +127,14 @@ jobs:
       - name: Install dependencies
         run: sh -x scripts/build/install_depends.sh
 
+      # The NATS modules (modules-contrib/) need libnats >= 3.14, which no
+      # Ubuntu release ships; without it they build nothing and their suites
+      # are skipped.  The cross legs build in another container: there the
+      # script skips itself and so do the suites.
+      - name: Install libnats
+        if: ${{ !endsWith(matrix.compiler, '-cross') }}
+        run: sh -x scripts/build/install_libnats.sh
+
       - name: Get libtap
         run: git clone https://github.com/zorgnax/libtap.git lib/libtap
 

Makefile.test

@@ -39,11 +39,24 @@ unit_tests: ensure_test_defs $(NAME)
 
 # One target per module suite.  The module is a prerequisite because `make all`
 # builds only the modules/ collection (Makefile:113), leaving a contrib module
-# with no .so for its suite to load.
+# with no .so for its suite to load -- and so are the other contrib modules
+# its config loads.
+test_cfg_contrib_modules=$(filter $(enabled_module_paths), \
+		$(wildcard $(addprefix modules-contrib/, \
+			$(shell sed -n 's/^loadmodule "\(.*\)\.so".*/\1/p' \
+				$(1)/test/opensips.cfg))))
+
+# A module whose optional library is missing builds no .so (its Makefile
+# skips itself, e.g. the NATS modules without libnats): there is nothing to
+# load, so its suite is skipped rather than failed.
 define module_test_rule
-test-$(notdir $(1)): ensure_test_defs $$(NAME) $(1)
+test-$(notdir $(1)): ensure_test_defs $$(NAME) $(1) $(call test_cfg_contrib_modules,$(1))
 	-@echo "          ====   $(notdir $(1))   ===="
-	./$$(NAME) -dd -T $(notdir $(1)) -w .
+	@if [ ! -f $(1)/$(notdir $(1)).so ]; then \
+		echo "          skipped: $(notdir $(1)).so was not built"; \
+	else \
+		./$$(NAME) -dd -T $(notdir $(1)) -w .; \
+	fi
 endef
 $(foreach m,$(test_module_paths),$(eval $(call module_test_rule,$(m))))
 

modules-contrib/cachedb_nats/Makefile

@@ -0,0 +1,25 @@
+# WARNING: do not run this directly, it should be run by the master Makefile
+
+include ../../Makefile.defs
+
+# External libnats dependency probe (sets NATS_FOUND if available).
+include ../nats/Makefile.nats
+
+ifeq ($(NATS_FOUND),)
+$(info [skip] cachedb_nats.so — libnats C client not detected (install libnats-dev or set LOCALBASE))
+.PHONY: all clean install modules
+all clean install modules: ; @true
+else
+
+auto_gen=
+NAME=cachedb_nats.so
+
+
+# EVI support for E_NATS_KV_CHANGE events (KV watcher -> OpenSIPS scripts)
+
+LIBS += -lpthread
+
+include ../../Makefile.modules
+
+
+endif