monitor: add make installcheck target and fix regression test

Add a top-level 'make installcheck' target that builds the PG16 test
Docker image and runs the monitor's SQL regression suite (pg_regress)
inside a fresh container.  Defaults to PGVERSION=16; override with
INSTALLCHECK_PGVERSION=17 etc.

Fix node_active_protocol.sql to work in the full regression sequence:
- Pass number_sync_standbys to create_formation() (5-arg form)
- Capture registered node IDs via \\gset after registration so the test
  is not sensitive to how many nodes prior tests (monitor, workers) created
- Move node_active_protocol before dummy_update in REGRESS order to avoid
  running against a downgraded 'dummy' extension version

Update expected/node_active_protocol.out from the actual pg_regress output.

Author: dimitri

Makefile

@@ -105,6 +105,26 @@ check: check-monitor ;
 check-monitor: install-monitor
 	$(MAKE) -C src/monitor/ installcheck
 
+# Run SQL regression tests (pg_regress installcheck) inside a Docker container.
+# Defaults to PG16; override with PGVERSION=17 etc.
+# Usage: make installcheck [PGVERSION=16]
+INSTALLCHECK_PGVERSION ?= 16
+.PHONY: installcheck
+installcheck: build-test-pg$(INSTALLCHECK_PGVERSION)
+	docker run --rm \
+	  $(TEST_CONTAINER_NAME):pg$(INSTALLCHECK_PGVERSION) \
+	  bash -c ' \
+	    initdb --auth=trust --username=docker -D /tmp/pgdata && \
+	    printf "shared_preload_libraries = '"'"'pgautofailover'"'"'\n" \
+	      >> /tmp/pgdata/postgresql.conf && \
+	    pg_ctl start -D /tmp/pgdata -l /tmp/pgdata/pg.log -o "-k /tmp -p 5432" && \
+	    sudo chmod -R a+w /usr/src/pg_auto_failover/src/monitor && \
+	    make -C /usr/src/pg_auto_failover/src/monitor installcheck \
+	         PGHOST=/tmp PGPORT=5432 PGUSER=docker \
+	    || { pg_ctl stop -D /tmp/pgdata; exit 1; } && \
+	    pg_ctl stop -D /tmp/pgdata \
+	  '
+
 .PHONY: clean
 clean: clean-monitor clean-bin ;
 

src/monitor/Makefile

@@ -14,7 +14,7 @@ MODULE_big = $(EXTENSION)
 OBJS = $(patsubst ${SRC_DIR}%.c,%.o,$(wildcard ${SRC_DIR}*.c))
 PG_CPPFLAGS = -std=c99 -Wall -Werror -Wno-unused-parameter -Iinclude -I$(libpq_srcdir) -g
 SHLIB_LINK = $(libpq)
-REGRESS = create_extension monitor workers dummy_update node_active_protocol drop_extension upgrade
+REGRESS = create_extension monitor workers node_active_protocol dummy_update drop_extension upgrade
 
 PG_CONFIG ?= pg_config
 PGXS = $(shell $(PG_CONFIG) --pgxs)