Fix typo in activity query

* Add a query for pg_stat_io metrics grouped by backend type

* Switch some unsupported values from 0 to NULL to better reflect their
  nonexistence

DEBIAN/control

@@ -3,7 +3,7 @@ Version: 1.0
 Section: utils
 Priority: optional
 Architecture: all
-Depends: logrotate, python3 (>= 3.6), python3-psycopg2, python3-yaml, systemd
+Depends: logrotate, python3 (>= 3.6), python3-psycopg2, python3-requests, python3-yaml, systemd
 Maintainer: James Campbell <james@commandprompt.com>
 Homepage: https://www.commandprompt.com
 Description: A bridge to sit between monitoring tools and PostgreSQL

GENTOO/pgmon-1.0.3.ebuild

@@ -0,0 +1,74 @@
+# Copyright 2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+PYTHON_COMPAT=( python3_{6..13} )
+
+inherit python-r1 systemd
+
+DESCRIPTION="PostgreSQL monitoring bridge"
+HOMEPAGE="None"
+
+LICENSE="BSD"
+SLOT="0"
+KEYWORDS="amd64"
+
+SRC_URI="https://code2.shh-dot-com.org/james/${PN}/releases/download/v${PV}/${P}.tar.bz2"
+
+IUSE="-systemd"
+
+DEPEND="
+	${PYTHON_DEPS}
+	dev-python/psycopg:2
+	dev-python/pyyaml
+	dev-python/requests
+	app-admin/logrotate
+	"
+RDEPEND="${DEPEND}"
+BDEPEND=""
+
+#RESTRICT="fetch"
+
+#S="${WORKDIR}/${PN}"
+
+#pkg_nofetch() {
+#	einfo "Please download"
+#	einfo "  - ${P}.tar.bz2"
+#	einfo "from ${HOMEPAGE} and place it in your DISTDIR directory."
+#	einfo "The file should be owned by portage:portage."
+#}
+
+src_compile() {
+	true
+}
+
+src_install() {
+	# Install init script
+	if ! use systemd ; then
+		newinitd "openrc/pgmon.initd" pgmon
+		newconfd "openrc/pgmon.confd" pgmon
+	fi
+
+	# Install systemd unit
+	if use systemd ; then
+		systemd_dounit "systemd/pgmon.service"
+	fi
+
+	# Install script
+	exeinto /usr/bin
+	newexe "src/pgmon.py" pgmon
+
+	# Install default config
+	diropts -o root -g root -m 0755
+	insinto /etc/pgmon
+	doins "sample-config/pgmon.yml"
+	doins "sample-config/pgmon-metrics.yml"
+
+	# Install logrotate config
+	insinto /etc/logrotate.d
+	newins "logrotate/pgmon.logrotate" pgmon
+
+	# Install man page
+	doman manpages/pgmon.1
+}

Makefile

@@ -23,7 +23,7 @@ SUPPORTED := ubuntu-20.04 \
 # These targets are the main ones to use for most things.
 ##
 
-.PHONY: all clean tgz test query-tests install
+.PHONY: all clean tgz test query-tests install-common install-openrc install-systemd
 
 
 # Build all packages
@@ -34,7 +34,7 @@ all: $(foreach distro_release, $(SUPPORTED), package-$(distro_release))
 .PHONY: package-gentoo
 package-gentoo:
 	mkdir -p $(BUILD_DIR)/gentoo
-	tar --transform "s,^\.,$(PACKAGE_NAME)-$(VERSION)," -acjf $(BUILD_DIR)/gentoo/$(PACKAGE_NAME)-$(VERSION).tar.bz2 --exclude $(BUILD_DIR) .
+	tar --transform "s,^,$(PACKAGE_NAME)-$(VERSION)/," -acjf $(BUILD_DIR)/gentoo/$(PACKAGE_NAME)-$(VERSION).tar.bz2 --exclude .gitignore $(shell git ls-tree --full-tree --name-only -r HEAD)
 
 
 # Create a deb package
@@ -54,7 +54,7 @@ package-%:
 tgz:
 	rm -rf $(BUILD_DIR)/tgz/root
 	mkdir -p $(BUILD_DIR)/tgz/root
-	$(MAKE) install DESTDIR=$(BUILD_DIR)/tgz/root
+	$(MAKE) install-openrc DESTDIR=$(BUILD_DIR)/tgz/root
 	tar -cz -f $(BUILD_DIR)/tgz/$(PACKAGE_NAME)-$(VERSION).tgz -C $(BUILD_DIR)/tgz/root .
 
 # Clean up the build directory
@@ -69,18 +69,17 @@ test:
 query-tests:
 	cd tests ; ./run-tests.sh
 
-# Install the script at the specified base directory
+# Install the script at the specified base directory (common components)
-install:
+install-common:
 	# Set up directories
 	mkdir -p $(DESTDIR)/etc/$(PACKAGE_NAME)
 	mkdir -p ${DESTDIR}/etc/logrotate.d
-	mkdir -p $(DESTDIR)/lib/systemd/system
+	mkdir -p $(DESTDIR)/usr/bin
-	mkdir -p $(DESTDIR)/usr/local/bin
 	mkdir -p $(DESTDIR)/usr/share/man/man1
 	
 	# Install script
-	cp $(SCRIPT) $(DESTDIR)/usr/local/bin/$(PACKAGE_NAME)
+	cp $(SCRIPT) $(DESTDIR)/usr/bin/$(PACKAGE_NAME)
-	chmod 755 $(DESTDIR)/usr/local/bin/$(PACKAGE_NAME)
+	chmod 755 $(DESTDIR)/usr/bin/$(PACKAGE_NAME)
 	
 	# Install manpage
 	cp manpages/* $(DESTDIR)/usr/share/man/man1/
@@ -89,12 +88,36 @@ install:
 	# Install sample config
 	cp sample-config/* $(DESTDIR)/etc/$(PACKAGE_NAME)/
 	
-	# Install systemd unit files
-	cp systemd/* $(DESTDIR)/lib/systemd/system/
-	
 	# Install logrotate config
 	cp logrotate/${PACKAGE_NAME}.logrotate ${DESTDIR}/etc/logrotate.d/${PACKAGE_NAME}
 
+# Install for systemd
+install-systemd:
+	# Install the common stuff
+	$(MAKE) install-common
+	
+	# Set up directories
+	mkdir -p $(DESTDIR)/lib/systemd/system
+	
+	# Install systemd unit files
+	cp systemd/* $(DESTDIR)/lib/systemd/system/
+
+# Install for open-rc
+install-openrc:
+	# Install the common stuff
+	$(MAKE) install-common
+	
+	# Set up directories
+	mkdir -p $(DESTDIR)/etc/init.d
+	mkdir -p $(DESTDIR)/etc/conf.d
+	
+	# Install init script
+	cp openrc/pgmon.initd $(DESTDIR)/etc/init.d/pgmon
+	chmod 755 $(DESTDIR)/etc/init.d/pgmon
+	
+	# Install init script config file
+	cp openrc/pgmon.confd $(DESTDIR)/etc/conf.d/pgmon
+
 
 # Run all of the install tests
 .PHONY: install-tests debian-%-install-test rockylinux-%-install-test ubuntu-%-install-test gentoo-install-test
@@ -167,7 +190,7 @@ package-image-%:
 
 # Debian package creation
 actually-package-debian-%:
-	$(MAKE) install DESTDIR=/output/debian-$*
+	$(MAKE) install-systemd DESTDIR=/output/debian-$*
 	cp -r --preserve=mode DEBIAN /output/debian-$*/
 	dpkg-deb -Zgzip --build /output/debian-$* "/output/$(PACKAGE_NAME)-$(VERSION)-debian-$*.deb"
 
@@ -182,7 +205,7 @@ actually-package-rockylinux-%:
 
 # Ubuntu package creation
 actually-package-ubuntu-%:
-	$(MAKE) install DESTDIR=/output/ubuntu-$*
+	$(MAKE) install-systemd DESTDIR=/output/ubuntu-$*
 	cp -r --preserve=mode DEBIAN /output/ubuntu-$*/
 	dpkg-deb -Zgzip --build /output/ubuntu-$* "/output/$(PACKAGE_NAME)-$(VERSION)-ubuntu-$*.deb"
 

RPM/pgmon-el7.spec

@@ -7,7 +7,7 @@ License: MIT
 URL: https://www.commandprompt.com
 
 BuildArch: noarch
-Requires: logrotate, python, python-psycopg2, PyYAML, systemd
+Requires: logrotate, python, python-psycopg2, PyYAML, python-requests, systemd
 
 %description
 A bridge to sit between monitoring tools and PostgreSQL
@@ -19,7 +19,7 @@ A bridge to sit between monitoring tools and PostgreSQL
 # Do nothing since we have nothing to build
 
 %install
-make -C /src install DESTDIR=%{buildroot}
+make -C /src install-systemd DESTDIR=%{buildroot}
 
 %files
 /etc/logrotate.d/pgmon
@@ -28,7 +28,7 @@ make -C /src install DESTDIR=%{buildroot}
 /etc/pgmon/pgmon-service.conf
 /lib/systemd/system/pgmon.service
 /lib/systemd/system/pgmon@.service
-/usr/local/bin/pgmon
+/usr/bin/pgmon
 /usr/share/man/man1/pgmon.1.gz
 
 %post

RPM/pgmon.spec

@@ -7,7 +7,7 @@ License: MIT
 URL: https://www.commandprompt.com
 
 BuildArch: noarch
-Requires: logrotate, python3, python3-psycopg2, python3-pyyaml, systemd
+Requires: logrotate, python3, python3-psycopg2, python3-pyyaml, python3-requests, systemd
 
 %description
 A bridge to sit between monitoring tools and PostgreSQL
@@ -19,7 +19,7 @@ A bridge to sit between monitoring tools and PostgreSQL
 # Do nothing since we have nothing to build
 
 %install
-make -C /src install DESTDIR=%{buildroot}
+make -C /src install-systemd DESTDIR=%{buildroot}
 
 %files
 /etc/logrotate.d/pgmon
@@ -28,7 +28,7 @@ make -C /src install DESTDIR=%{buildroot}
 /etc/pgmon/pgmon-service.conf
 /lib/systemd/system/pgmon.service
 /lib/systemd/system/pgmon@.service
-/usr/local/bin/pgmon
+/usr/bin/pgmon
 /usr/share/man/man1/pgmon.1.gz
 
 %post

sample-config/pgmon-metrics.yml

@@ -1,63 +1,307 @@
 metrics:
+  ##
   # Discovery metrics
+  ##
   discover_dbs:
     type: set
     query:
-      0: SELECT datname AS dbname FROM pg_database
+      0: >
+        SELECT datname AS dbname
+        FROM pg_database
+
+  # Note: If the user lacks sufficient privileges, these fields will be NULL.
+  #       The WHERE clause is intended to prevent Zabbix from discovering a
+  #       connection it cannot monitor.  Ideally this would generate an error
+  #       instead.
   discover_rep:
     type: set
     query:
-      0: SELECT client_addr || '_' || regexp_replace(application_name, '[ ,]', '_', 'g') AS repid, client_addr, state FROM pg_stat_replication
+      0: >
+        SELECT host(client_addr) || '_' || regexp_replace(application_name, '[ ,]', '_', 'g') AS repid,
+               client_addr,
+               state
+        FROM pg_stat_replication
+        WHERE state IS NOT NULL
+
   discover_slots:
     type: set
     query:
-      90400: SELECT slot_name, plugin, slot_type, database, false as temporary, active FROM pg_replication_slots
+      90400: >
-      100000: SELECT slot_name, plugin, slot_type, database, temporary, active FROM pg_replication_slots
+        SELECT slot_name,
+               plugin,
+               slot_type,
+               database,
+               false as temporary,
+               active
+        FROM pg_replication_slots
+      100000: >
+        SELECT slot_name,
+               plugin,
+               slot_type,
+               database,
+               temporary,
+               active
+        FROM pg_replication_slots
 
+
+  ##
   # cluster-wide metrics
+  ##
   version:
     type: value
     query:
       0: SHOW server_version_num
+
   max_frozen_age:
     type: row
     query:
-      0: SELECT max(age(datfrozenxid)), max(mxid_age(datminmxid)) FROM pg_database
+      0: >
+        SELECT max(age(datfrozenxid)) AS xid_age,
+               NULL AS mxid_age
+        FROM pg_database
+      90600: >
+        SELECT max(age(datfrozenxid)) AS xid_age,
+               max(mxid_age(datminmxid)) AS mxid_age
+        FROM pg_database
 
+  bgwriter:
+    type: row
+    query:
+      0: >
+        SELECT checkpoints_timed,
+               checkpoints_req,
+               checkpoint_write_time,
+               checkpoint_sync_time,
+               buffers_checkpoint,
+               buffers_clean,
+               maxwritten_clean,
+               buffers_backend,
+               buffers_backend_fsync,
+               buffers_alloc
+        FROM pg_stat_bgwriter
+      170000: >
+        SELECT cp.num_timed AS checkpoints_timed,
+               cp.num_requested AS checkpoints_req,
+               cp.write_time AS checkpoint_write_time,
+               cp.sync_time AS checkpoint_sync_time,
+               cp.buffers_written AS buffers_checkpoint,
+               bg.buffers_clean AS buffers_clean,
+               bg.maxwritten_clean AS maxwritten_clean,
+               NULL AS buffers_backend,
+               NULL AS buffers_backend_fsync,
+               bg.buffers_alloc AS buffers_alloc
+        FROM pg_stat_bgwriter bg
+        CROSS JOIN pg_stat_checkpointer cp
+
+  io_per_backend:
+    type: set
+    query:
+      160000: >
+        SELECT backend_type,
+               COALESCE(SUM(reads * op_bytes), 0) AS reads,
+               COALESCE(SUM(read_time), 0) AS read_time,
+               COALESCE(SUM(writes * op_bytes), 0) AS writes,
+               COALESCE(SUM(write_time), 0) AS write_time,
+               COALESCE(SUM(writebacks * op_bytes), 0) AS writebacks,
+               COALESCE(SUM(writeback_time), 0) AS writeback_time,
+               COALESCE(SUM(extends * op_bytes), 0) AS extends,
+               COALESCE(SUM(extend_time), 0) AS extend_time,
+               COALESCE(SUM(op_bytes), 0) AS op_bytes,
+               COALESCE(SUM(hits), 0) AS hits,
+               COALESCE(SUM(evictions), 0) AS evictions,
+               COALESCE(SUM(reuses), 0) AS reuses,
+               COALESCE(SUM(fsyncs), 0) AS fsyncs,
+               COALESCE(SUM(fsync_time), 0) AS fsync_time
+        FROM pg_stat_io
+        GROUP BY backend_type
+
+
+  ##
   # Per-database metrics
+  ##
   db_stats:
     type: row
     query:
-      0: SELECT numbackends, xact_commit, xact_rollback, blks_read, blks_hit, tup_returned, tup_fetched, tup_inserted, tup_updated, tup_deleted, conflicts, temp_files, temp_bytes, deadlocks, blk_read_time, blk_write_time, extract('epoch' from stats_reset)::float FROM pg_stat_database WHERE datname = %(dbname)s
+      0: >
-      140000: SELECT numbackends, xact_commit, xact_rollback, blks_read, blks_hit, tup_returned, tup_fetched, tup_inserted, tup_updated, tup_deleted, conflicts, temp_files, temp_bytes, deadlocks, COALESCE(checksum_failures, 0) AS checksum_failures, blk_read_time, blk_write_time, session_time, active_time, idle_in_transaction_time, sessions, sessions_abandoned, sessions_fatal, sessions_killed, extract('epoch' from stats_reset)::float FROM pg_stat_database WHERE datname = %(dbname)s
+        SELECT numbackends,
+               xact_commit,
+               xact_rollback,
+               blks_read,
+               blks_hit,
+               tup_returned,
+               tup_fetched,
+               tup_inserted,
+               tup_updated,
+               tup_deleted,
+               conflicts,
+               temp_files,
+               temp_bytes,
+               deadlocks,
+               NULL AS checksum_failures,
+               blk_read_time,
+               blk_write_time,
+               NULL AS session_time,
+               NULL AS active_time,
+               NULL AS idle_in_transaction_time,
+               NULL AS sessions,
+               NULL AS sessions_abandoned,
+               NULL AS sessions_fatal,
+               NULL AS sessions_killed,
+               extract('epoch' from stats_reset) AS stats_reset
+        FROM pg_stat_database WHERE datname = %(dbname)s
+      140000: >
+        SELECT numbackends,
+               xact_commit,
+               xact_rollback,
+               blks_read,
+               blks_hit,
+               tup_returned,
+               tup_fetched,
+               tup_inserted,
+               tup_updated,
+               tup_deleted,
+               conflicts,
+               temp_files,
+               temp_bytes,
+               deadlocks,
+               COALESCE(checksum_failures, 0) AS checksum_failures,
+               blk_read_time,
+               blk_write_time,
+               session_time,
+               active_time,
+               idle_in_transaction_time,
+               sessions,
+               sessions_abandoned,
+               sessions_fatal,
+               sessions_killed,
+               extract('epoch' from stats_reset) AS stats_reset
+        FROM pg_stat_database WHERE datname = %(dbname)s
     test_args:
       dbname: postgres
 
+  hit_ratios:
+    type: row
+    query:
+      0: >
+        SELECT sum(heap_blks_read)::float / NULLIF(sum(heap_blks_read + heap_blks_hit), 0) AS avg_heap_hit_ratio,
+               sum(idx_blks_hit)::float / NULLIF(sum(idx_blks_read + idx_blks_hit), 0) AS avg_idx_hit_ratio,
+               sum(toast_blks_hit)::float / NULLIF(sum(toast_blks_read + toast_blks_hit), 0) AS avg_toast_hit_ratio,
+               sum(tidx_blks_hit)::float / NULLIF(sum(tidx_blks_read + tidx_blks_hit), 0) AS avg_tidx_hit_ratio
+        FROM pg_statio_all_tables
+    test_args:
+      dbname: postgres
+
+  activity:
+    type: set
+    query:
+      0: >
+        SELECT state,
+               count(*) AS backend_count,
+               COALESCE(EXTRACT(EPOCH FROM max(now() - state_change)), 0) AS max_state_time
+        FROM pg_stat_activity
+        WHERE datname = %(dbname)s
+        GROUP BY state
+    test_args:
+      dbname: postgres
+
+  sequence_usage:
+    type: value
+    query:
+# 9.2 lacks lateral joins, the pg_sequence_last_value function, and the pg_sequences view
+#      0: >
+#        SELECT COALESCE(MAX(pg_sequence_last_value(c.oid)::float / (pg_sequence_parameters(oid)).maximum_value), 0) AS max_usage
+#        FROM pg_class c
+#        WHERE c.relkind = 'S'
+# 9.3 - 9.6 lacks the pg_sequence_last_value function, and pg_sequences view
+#      90300: >
+#        SELECT COALESCE(MAX(pg_sequence_last_value(c.oid)::float / s.maximum_value), 0) AS max_usage
+#        FROM pg_class c
+#        CROSS JOIN LATERAL pg_sequence_parameters(c.oid) AS s
+#        WHERE c.relkind = 'S'
+      100000: SELECT COALESCE(MAX(last_value::float / max_value), 0) AS max_usage FROM pg_sequences;
+    test_args:
+      dbname: postgres
+
+  sequence_visibility:
+    type: row
+    query:
+      100000: >
+        SELECT COUNT(*) FILTER (WHERE has_sequence_privilege(c.oid, 'SELECT,USAGE')) AS visible_sequences,
+               COUNT(*) AS total_sequences
+        FROM pg_class AS c
+        WHERE relkind = 'S';
+
+
+  ##
+  # Per-replication metrics
+  ##
+  rep_stats:
+    type: row
+    query:
+      90400: >
+        SELECT pid, usename,
+               EXTRACT(EPOCH FROM backend_start) AS backend_start,
+               state,
+               pg_xlog_location_diff(pg_current_xlog_location(), sent_location) AS sent_lsn,
+               pg_xlog_location_diff(pg_current_xlog_location(), write_location) AS write_lsn,
+               pg_xlog_location_diff(pg_current_xlog_location(), flush_location) AS flush_lsn,
+               pg_xlog_location_diff(pg_current_xlog_location(), replay_location) AS replay_lsn,
+               NULL AS write_lag,
+               NULL AS flush_lag,
+               NULL AS replay_lag,
+               sync_state
+        FROM pg_stat_replication
+        WHERE host(client_addr) || '_' || regexp_replace(application_name, '[ ,]', '_', 'g') = %(repid)s
+      100000: >
+        SELECT pid, usename,
+               EXTRACT(EPOCH FROM backend_start) AS backend_start,
+               state,
+               pg_wal_lsn_diff(pg_current_wal_lsn(), sent_lsn) AS sent_lsn,
+               pg_wal_lsn_diff(pg_current_wal_lsn(), write_lsn) AS write_lsn,
+               pg_wal_lsn_diff(pg_current_wal_lsn(), flush_lsn) AS flush_lsn,
+               pg_wal_lsn_diff(pg_current_wal_lsn(), replay_lsn) AS replay_lsn,
+               COALESCE(EXTRACT(EPOCH FROM write_lag), 0) AS write_lag,
+               COALESCE(EXTRACT(EPOCH FROM flush_lag), 0) AS flush_lag,
+               COALESCE(EXTRACT(EPOCH FROM replay_lag), 0) AS replay_lag,
+               sync_state
+        FROM pg_stat_replication
+        WHERE host(client_addr) || '_' || regexp_replace(application_name, '[ ,]', '_', 'g') = %(repid)s
+    test_args:
+      repid: 127.0.0.1_test_rep
+
+
+  ##
+  # Per-slot metrics
+  ##
+  slot_stats:
+    type: row
+    query:
+      90400: >
+        SELECT NULL as active_pid,
+               xmin,
+               pg_xlog_location_diff(pg_current_xlog_location(), restart_lsn) AS restart_bytes,
+               NULL AS confirmed_flush_bytes
+        FROM pg_replication_slots WHERE slot_name = %(slot)s
+      90600: >
+        SELECT active_pid,
+               xmin,
+               pg_xlog_location_diff(pg_current_xlog_location(), restart_lsn) AS restart_bytes,
+               pg_xlog_location_diff(pg_current_xlog_location(), confirmed_flush_lsn) AS confirmed_flush_bytes
+        FROM pg_replication_slots WHERE slot_name = %(slot)s
+      100000: >
+        SELECT active_pid,
+               xmin,
+               pg_wal_lsn_diff(pg_current_wal_lsn(), restart_lsn) AS restart_bytes,
+               pg_wal_lsn_diff(pg_current_wal_lsn(), confirmed_flush_lsn) AS confirmed_flush_bytes
+        FROM pg_replication_slots WHERE slot_name = %(slot)s
+    test_args:
+      slot: test_slot
+
+
+  ##
   # Debugging
+  ##
   ntables:
     type: value
     query:
       0: SELECT count(*) AS ntables FROM pg_stat_user_tables
-
-  # Per-replication metrics
-  rep_stats:
-    type: row
-    query:
-      90400: SELECT * FROM pg_stat_replication WHERE client_addr || '_' || regexp_replace(application_name, '[ ,]', '_', 'g') = '{repid}'
-    test_args:
-      repid: 127.0.0.1_test_rep
-
-  # Debugging
-  sleep:
-    type: value
-    query:
-      0: SELECT now(), pg_sleep(5);
-
-  # Per-slot metrics
-  slot_stats:
-    type: row
-    query:
-      90400: SELECT active_pid, xmin, pg_xlog_location_diff(pg_current_xlog_location(), restart_lsn) AS restart_bytes, pg_xlog_location_diff(pg_current_xlog_location(), confirmed_flush_lsn) AS confirmed_flush_bytes FROM pg_replication_slots WHERE slot_name = '{slot}'
-      100000: SELECT active_pid, xmin, pg_wal_lsn_diff(pg_current_wal_lsn(), restart_lsn) AS restart_bytes, pg_wal_lsn_diff(pg_current_wal_lsn(), confirmed_flush_lsn) AS confirmed_flush_bytes FROM pg_replication_slots WHERE slot_name = '{slot}'
-    test_args:
-      slot: test_slot

src/pgmon.py

@@ -27,7 +27,9 @@ from urllib.parse import urlparse, parse_qs
 import requests
 import re
 
-VERSION = "1.0.2"
+from decimal import Decimal
+
+VERSION = "1.0.3"
 
 # Configuration
 config = {}
@@ -391,6 +393,16 @@ def get_query(metric, version):
     raise MetricVersionError("Missing metric query for PostgreSQL {}".format(version))
 
 
+def json_encode_special(obj):
+    """
+    Encoder function to handle types the standard JSON package doesn't know what
+    to do with
+    """
+    if isinstance(obj, Decimal):
+        return float(obj)
+    raise TypeError(f'Cannot serialize object of {type(obj)}')
+
+
 def run_query_no_retry(pool, return_type, query, args):
     """
     Run the query with no explicit retry code
@@ -408,13 +420,13 @@ def run_query_no_retry(pool, return_type, query, args):
                 elif return_type == "row":
                     if len(res) == 0:
                         return "[]"
-                    return json.dumps(res[0])
+                    return json.dumps(res[0], default=json_encode_special)
                 elif return_type == "column":
                     if len(res) == 0:
                         return "[]"
-                    return json.dumps([list(r.values())[0] for r in res])
+                    return json.dumps([list(r.values())[0] for r in res], default=json_encode_special)
                 elif return_type == "set":
-                    return json.dumps(res)
+                    return json.dumps(res, default=json_encode_special)
         except:
             dbname = pool.name
             if dbname in unhappy_cooldown:
@@ -497,13 +509,91 @@ def get_cluster_version():
     return cluster_version
 
 
+def version_num_to_release(version_num):
+    """
+    Extract the revease from a version_num.
+
+    In other words, this converts things like:
+        90603  => 9.6
+        130010 => 13
+    """
+    if version_num // 10000 < 10:
+        return version_num // 10000 + (version_num % 10000 // 100 / 10)
+    else:
+        return version_num // 10000
+
+
+def parse_version_rss(raw_rss, release):
+    """
+    Parse the raw RSS from the versions.rss feed to extract the latest version of
+    PostgreSQL that's availabe for the cluster being monitored.
+
+    This sets these global variables:
+        latest_version
+        release_supported
+
+    It is expected that the caller already holds the latest_version_lock lock.
+
+    params:
+        raw_rss: The raw rss text from versions.rss
+        release: The PostgreSQL release we care about (ex: 9.2, 14)
+    """
+    global latest_version
+    global release_supported
+
+    # Regular expressions for parsing the RSS document
+    version_line = re.compile(
+        r".*?([0-9][0-9.]+) is the latest release in the {} series.*".format(release)
+    )
+    unsupported_line = re.compile(r"^This version is unsupported")
+
+    # Loop through the RSS until we find the current release
+    release_found = False
+    for line in raw_rss.splitlines():
+        m = version_line.match(line)
+        if m:
+            # Note that we found the version we were looking for
+            release_found = True
+
+            # Convert the version to version_num format
+            version = m.group(1)
+            parts = list(map(int, version.split(".")))
+            if parts[0] < 10:
+                latest_version = int(
+                    "{}{:02}{:02}".format(parts[0], parts[1], parts[2])
+                )
+            else:
+                latest_version = int("{}00{:02}".format(parts[0], parts[1]))
+        elif release_found:
+            # The next line after the version tells if the version is supported
+            if unsupported_line.match(line):
+                release_supported = False
+            else:
+                release_supported = True
+            break
+
+    # Make sure we actually found it
+    if not release_found:
+        raise LatestVersionCheckError("Current release ({}) not found".format(release))
+
+    log.info(
+        "Got latest PostgreSQL version: {} supported={}".format(
+            latest_version, release_supported
+        )
+    )
+    log.debug(
+        "Next latest PostgreSQL version check will be after: {}".format(
+            latest_version_next_check
+        )
+    )
+
+
 def get_latest_version():
     """
     Get the latest supported version of the major PostgreSQL release running on the server being monitored.
     """
-    global latest_version
+
     global latest_version_next_check
-    global release_supported
 
     # If we don't know the latest version or it's past the recheck time, get the
     # version from the PostgreSQL RSS feed.  Only one thread needs to do this, so
@@ -513,6 +603,10 @@ def get_latest_version():
         or latest_version_next_check is None
         or latest_version_next_check < datetime.now()
     ):
+        # Note: we get the cluster version here before grabbing the latest_version_lock
+        #       lock so it's not held while trying to talk with the DB.
+        release = version_num_to_release(get_cluster_version())
+
         with latest_version_lock:
             # Only check if nobody already got the version before us
             if (
@@ -521,74 +615,17 @@ def get_latest_version():
                 or latest_version_next_check < datetime.now()
             ):
                 log.info("Checking latest PostgreSQL version")
-                cluster_version = get_cluster_version()
                 latest_version_next_check = datetime.now() + timedelta(
                     seconds=int(config["latest_version_check_period"])
                 )
 
-                # Extract the release
-                # 90603  => 9.6
-                # 130010 => 13
-                if cluster_version // 10000 < 10:
-                    release = cluster_version // 10000 + (
-                        cluster_version % 10000 // 100 / 10
-                    )
-                else:
-                    release = cluster_version // 10000
-
                 # Grab the RSS feed
                 raw_rss = requests.get("https://www.postgresql.org/versions.rss")
-                if raw_rss.status != 200:
+                if raw_rss.status_code != 200:
-                    raise LatestVersionCheckError("code={}".format(r.status))
+                    raise LatestVersionCheckError("code={}".format(r.status_code))
 
-                # Regular expressions for parsing the RSS document
+                # Parse the RSS body and set global variables
-                version_line = re.compile(
+                parse_version_rss(raw_rss.text, release)
-                    r"([0-9][0-9.]+) is the latest release in the ([0-9][0-9.]+) series"
-                )
-                unsupported_line = re.compile(r"^This version is unsupported")
-
-                # Loop through the RSS until we find the current release
-                release_found = False
-                for line in raw_rss.text.lines():
-                    m = version_line.match(line)
-                    if m:
-                        if release == int(m.group(2)):
-                            release_found = True
-                            version = float(m.group(1))
-                            if version < 10:
-                                parts = list(map(int, version.split(".")))
-                                latest_version = int(
-                                    "{}{:02}{:02}".format(parts[0], parts[1], parts[2])
-                                )
-                            else:
-                                parts = list(map(int, version.split(".")))
-                                latest_version = int(
-                                    "{}00{:02}".format(parts[0], parts[1])
-                                )
-                            release_found = True
-                    elif release_found:
-                        if unsupported.match(line):
-                            release_supported = False
-                        else:
-                            release_supported = True
-                        break
-
-                # Make sure we actually found it
-                if not release_found:
-                    raise LatestVersionCheckError(
-                        "Current release ({}) not found".format(release)
-                    )
-
-                log.info(
-                    "Got latest PostgreSQL version: {} supported={}".format(
-                        latest_version, release_supported
-                    )
-                )
-                log.debug(
-                    "Next latest PostgreSQL version check will be after: {}".format(
-                        latest_version_next_check
-                    )
-                )
 
     return latest_version
 
@@ -630,8 +667,25 @@ def test_queries():
     for name, metric in config["metrics"].items():
         # If the metric has arguments to use while testing, grab those
         args = metric.get("test_args", {})
-        # Run the query without the ability to retry.
+        print("Testing {} [{}]".format(name, ", ".join(["{}={}".format(key, value) for key, value in args.items()])))
-        res = sample_metric(dbname, name, args, retry=False)
+        # When testing against a docker container, we may end up connecting
+        # before the service is truly up (it restarts during the initialization
+        # phase).  To cope with this, we'll allow a few connection failures.
+        tries = 5
+        while True:
+            # Run the query without the ability to retry
+            try:
+                res = sample_metric(dbname, name, args, retry=False)
+                break
+            except MetricVersionError:
+                res = "Unsupported for this version"
+                break
+            except psycopg2.OperationalError as e:
+                print("Error encountered, {} tries left: {}".format(tries, e))
+                if tries <= 0:
+                    raise
+                time.sleep(1)
+            tries -= 1
         # Compare the result to the provided sample results
         # TODO
         print("{} -> {}".format(name, res))
@@ -674,6 +728,22 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
         if metric_name == "agent_version":
             self._reply(200, VERSION)
             return
+        elif metric_name == "latest_version_info":
+            try:
+                get_latest_version()
+                self._reply(
+                    200,
+                    json.dumps(
+                        {
+                            "latest": latest_version,
+                            "supported": 1 if release_supported else 0,
+                        }
+                    ),
+                )
+            except LatestVersionCheckError as e:
+                log.error("Failed to retrieve latest version information: {}".format(e))
+                self._reply(503, "Failed to retrieve latest version info")
+            return
 
         # Note: parse_qs returns the values as a list.  Since we always expect
         #       single values, just grab the first from each.

src/test_pgmon.py

@@ -5,11 +5,103 @@ import tempfile
 
 import logging
 
+from decimal import Decimal
+import json
+
 import pgmon
 
 # Silence most logging output
 logging.disable(logging.CRITICAL)
 
+versions_rss = """
+<?xml version="1.0" encoding="utf-8"?>
+<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>PostgreSQL latest versions</title><link>https://www.postgresql.org/</link><description>PostgreSQL latest versions</description><atom:link href="https://www.postgresql.org/versions.rss" rel="self"/><language>en-us</language><lastBuildDate>Thu, 08 May 2025 00:00:00 +0000</lastBuildDate><item><title>17.5
+</title><link>https://www.postgresql.org/docs/17/release-17-5.html</link><description>17.5 is the latest release in the 17 series.
+
+</description><pubDate>Thu, 08 May 2025 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/17/release-17-5.html</guid></item><item><title>16.9
+</title><link>https://www.postgresql.org/docs/16/release-16-9.html</link><description>16.9 is the latest release in the 16 series.
+
+</description><pubDate>Thu, 08 May 2025 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/16/release-16-9.html</guid></item><item><title>15.13
+</title><link>https://www.postgresql.org/docs/15/release-15-13.html</link><description>15.13 is the latest release in the 15 series.
+
+</description><pubDate>Thu, 08 May 2025 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/15/release-15-13.html</guid></item><item><title>14.18
+</title><link>https://www.postgresql.org/docs/14/release-14-18.html</link><description>14.18 is the latest release in the 14 series.
+
+</description><pubDate>Thu, 08 May 2025 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/14/release-14-18.html</guid></item><item><title>13.21
+</title><link>https://www.postgresql.org/docs/13/release-13-21.html</link><description>13.21 is the latest release in the 13 series.
+
+</description><pubDate>Thu, 08 May 2025 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/13/release-13-21.html</guid></item><item><title>12.22
+</title><link>https://www.postgresql.org/docs/12/release-12-22.html</link><description>12.22 is the latest release in the 12 series.
+This version is unsupported!
+</description><pubDate>Thu, 21 Nov 2024 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/12/release-12-22.html</guid></item><item><title>11.22
+</title><link>https://www.postgresql.org/docs/11/release-11-22.html</link><description>11.22 is the latest release in the 11 series.
+This version is unsupported!
+</description><pubDate>Thu, 09 Nov 2023 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/11/release-11-22.html</guid></item><item><title>10.23
+</title><link>https://www.postgresql.org/docs/10/release-10-23.html</link><description>10.23 is the latest release in the 10 series.
+This version is unsupported!
+</description><pubDate>Thu, 10 Nov 2022 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/10/release-10-23.html</guid></item><item><title>9.6.24
+</title><link>https://www.postgresql.org/docs/9.6/release-9-6-24.html</link><description>9.6.24 is the latest release in the 9.6 series.
+This version is unsupported!
+</description><pubDate>Thu, 11 Nov 2021 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/9.6/release-9-6-24.html</guid></item><item><title>9.5.25
+</title><link>https://www.postgresql.org/docs/9.5/release-9-5-25.html</link><description>9.5.25 is the latest release in the 9.5 series.
+This version is unsupported!
+</description><pubDate>Thu, 11 Feb 2021 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/9.5/release-9-5-25.html</guid></item><item><title>9.4.26
+</title><link>https://www.postgresql.org/docs/9.4/release-9-4-26.html</link><description>9.4.26 is the latest release in the 9.4 series.
+This version is unsupported!
+</description><pubDate>Thu, 13 Feb 2020 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/9.4/release-9-4-26.html</guid></item><item><title>9.3.25
+</title><link>https://www.postgresql.org/docs/9.3/release-9-3-25.html</link><description>9.3.25 is the latest release in the 9.3 series.
+This version is unsupported!
+</description><pubDate>Thu, 08 Nov 2018 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/9.3/release-9-3-25.html</guid></item><item><title>9.2.24
+</title><link>https://www.postgresql.org/docs/9.2/release-9-2-24.html</link><description>9.2.24 is the latest release in the 9.2 series.
+This version is unsupported!
+</description><pubDate>Thu, 09 Nov 2017 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/9.2/release-9-2-24.html</guid></item><item><title>9.1.24
+</title><link>https://www.postgresql.org/docs/9.1/release-9-1-24.html</link><description>9.1.24 is the latest release in the 9.1 series.
+This version is unsupported!
+</description><pubDate>Thu, 27 Oct 2016 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/9.1/release-9-1-24.html</guid></item><item><title>9.0.23
+</title><link>https://www.postgresql.org/docs/9.0/release-9-0-23.html</link><description>9.0.23 is the latest release in the 9.0 series.
+This version is unsupported!
+</description><pubDate>Thu, 08 Oct 2015 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/9.0/release-9-0-23.html</guid></item><item><title>8.4.22
+</title><link>https://www.postgresql.org/docs/8.4/release-8-4-22.html</link><description>8.4.22 is the latest release in the 8.4 series.
+This version is unsupported!
+</description><pubDate>Thu, 24 Jul 2014 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/8.4/release-8-4-22.html</guid></item><item><title>8.3.23
+</title><link>https://www.postgresql.org/docs/8.3/release-8-3-23.html</link><description>8.3.23 is the latest release in the 8.3 series.
+This version is unsupported!
+</description><pubDate>Thu, 07 Feb 2013 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/8.3/release-8-3-23.html</guid></item><item><title>8.2.23
+</title><link>https://www.postgresql.org/docs/8.2/release-8-2-23.html</link><description>8.2.23 is the latest release in the 8.2 series.
+This version is unsupported!
+</description><pubDate>Mon, 05 Dec 2011 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/8.2/release-8-2-23.html</guid></item><item><title>8.1.23
+</title><link>https://www.postgresql.org/docs/8.1/release.html</link><description>8.1.23 is the latest release in the 8.1 series.
+This version is unsupported!
+</description><pubDate>Thu, 16 Dec 2010 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/8.1/release.html</guid></item><item><title>8.0.26
+</title><link>https://www.postgresql.org/docs/8.0/release.html</link><description>8.0.26 is the latest release in the 8.0 series.
+This version is unsupported!
+</description><pubDate>Mon, 04 Oct 2010 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/8.0/release.html</guid></item><item><title>7.4.30
+</title><link>https://www.postgresql.org/docs/7.4/release.html</link><description>7.4.30 is the latest release in the 7.4 series.
+This version is unsupported!
+</description><pubDate>Mon, 04 Oct 2010 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/7.4/release.html</guid></item><item><title>7.3.21
+</title><link>https://www.postgresql.org/docs/7.3/release.html</link><description>7.3.21 is the latest release in the 7.3 series.
+This version is unsupported!
+</description><pubDate>Mon, 07 Jan 2008 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/7.3/release.html</guid></item><item><title>7.2.8
+</title><link>https://www.postgresql.org/docs/7.2/release.html</link><description>7.2.8 is the latest release in the 7.2 series.
+This version is unsupported!
+</description><pubDate>Mon, 09 May 2005 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/7.2/release.html</guid></item><item><title>7.1.3
+</title><link>https://www.postgresql.org/docs/7.1/release.html</link><description>7.1.3 is the latest release in the 7.1 series.
+This version is unsupported!
+</description><pubDate>Fri, 17 Aug 2001 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/7.1/release.html</guid></item><item><title>7.0.3
+</title><link>https://www.postgresql.org/docs/7.0/release.htm</link><description>7.0.3 is the latest release in the 7.0 series.
+This version is unsupported!
+</description><pubDate>Sun, 12 Nov 2000 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/7.0/release.htm</guid></item><item><title>6.5.3
+</title><link>https://www.postgresql.org/docs/6.5/release.htm</link><description>6.5.3 is the latest release in the 6.5 series.
+This version is unsupported!
+</description><pubDate>Thu, 04 Nov 1999 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/6.5/release.htm</guid></item><item><title>6.4.2
+</title><link>https://www.postgresql.org/docs/6.4/release.htm</link><description>6.4.2 is the latest release in the 6.4 series.
+This version is unsupported!
+</description><pubDate>Sun, 03 Jan 1999 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/6.4/release.htm</guid></item><item><title>6.3.2
+</title><link>https://www.postgresql.org/docs/6.3/c2701.htm</link><description>6.3.2 is the latest release in the 6.3 series.
+This version is unsupported!
+</description><pubDate>Mon, 23 Feb 1998 00:00:00 +0000</pubDate><guid>https://www.postgresql.org/docs/6.3/c2701.htm</guid></item></channel></rss>
+"""
+
 
 class TestPgmonMethods(unittest.TestCase):
     ##
@@ -172,13 +264,16 @@ class TestPgmonMethods(unittest.TestCase):
     def test_get_query__versions(self):
         metric = {"type": "value", "query": {0: "DEFAULT", 110000: "NEW"}}
 
-        # Test getting the default version of a query with no lower bound and a newer version
+        # Test getting the default version of a query with no lower bound and a newer
+        # version
         self.assertEqual(pgmon.get_query(metric, 100000), "DEFAULT")
 
-        # Test getting the newer version of a query with no lower bound and a newer version for the newer version
+        # Test getting the newer version of a query with no lower bound and a newer
+        # version for the newer version
         self.assertEqual(pgmon.get_query(metric, 110000), "NEW")
 
-        # Test getting the newer version of a query with no lower bound and a newer version for an even newer version
+        # Test getting the newer version of a query with no lower bound and a newer
+        # version for an even newer version
         self.assertEqual(pgmon.get_query(metric, 160000), "NEW")
 
         # Test getting a version in bwtween two other versions
@@ -272,7 +367,8 @@ metrics:
     def test_read_config__include(self):
         pgmon.config = {}
 
-        # Test reading a config that includes other files (absolute and relative paths, multiple levels)
+        # Test reading a config that includes other files (absolute and relative paths,
+        # multiple levels)
         with tempfile.TemporaryDirectory() as tmpdirname:
             with open(f"{tmpdirname}/config.yml", "w") as f:
                 f.write(
@@ -661,3 +757,55 @@ metrics:
             )
         self.assertEqual(pgmon.config["dbuser"], "postgres")
         self.assertEqual(pgmon.config["metrics"]["test1"]["query"][0], "TEST1")
+
+    def test_version_num_to_release__valid(self):
+        self.assertEqual(pgmon.version_num_to_release(90602), 9.6)
+        self.assertEqual(pgmon.version_num_to_release(130002), 13)
+
+    def test_parse_version_rss__simple(self):
+        pgmon.parse_version_rss(versions_rss, 13)
+        self.assertEqual(pgmon.latest_version, 130021)
+        self.assertTrue(pgmon.release_supported)
+
+        pgmon.parse_version_rss(versions_rss, 9.6)
+        self.assertEqual(pgmon.latest_version, 90624)
+        self.assertFalse(pgmon.release_supported)
+
+    def test_parse_version_rss__missing(self):
+        # Test asking about versions that don't exist
+        self.assertRaises(
+            pgmon.LatestVersionCheckError, pgmon.parse_version_rss, versions_rss, 9.7
+        )
+
+        self.assertRaises(
+            pgmon.LatestVersionCheckError, pgmon.parse_version_rss, versions_rss, 99
+        )
+
+    def test_get_latest_version(self):
+        # Define a cluster version here so the test doesn't need a database
+        pgmon.cluster_version_next_check = datetime.now() + timedelta(hours=1)
+        pgmon.cluster_version = 90623
+
+        # Set up a default config
+        pgmon.update_deep(pgmon.config, pgmon.default_config)
+
+        # Make sure we can pull the RSS file (we assume the 9.6 series won't be getting
+        # any more updates)
+        self.assertEqual(pgmon.get_latest_version(), 90624)
+
+    def test_json_encode_special(self):
+        # Confirm that we're getting the right type
+        self.assertFalse(isinstance(Decimal('0.5'), float))
+        self.assertTrue(isinstance(pgmon.json_encode_special(Decimal('0.5')), float))
+
+        # Make sure we get sane values
+        self.assertEqual(pgmon.json_encode_special(Decimal('0.5')), 0.5)
+        self.assertEqual(pgmon.json_encode_special(Decimal('12')), 12.0)
+
+        # Make sure we can still fail for other types
+        self.assertRaises(
+            TypeError, pgmon.json_encode_special, object
+        )
+
+        # Make sure we can actually serialize a Decimal
+        self.assertEqual(json.dumps(Decimal('2.5'), default=pgmon.json_encode_special), '2.5')

systemd/pgmon@.service

@@ -7,7 +7,7 @@ After=network.target
 [Service]
 EnvironmentFile=/etc/pgmon/%i-service.conf
 User=${SERVICE_USER:-postgres}
-ExecStart=/usr/local/bin/pgmon -c /etc/pgmon/%i.yml
+ExecStart=/usr/bin/pgmon -c /etc/pgmon/%i.yml
 ExecReload=kill -HUP $MAINPID
 Restart=on-failure
 Type=exec

tests/Dockerfile

@@ -2,6 +2,7 @@ FROM alpine:3.21
 
 RUN apk update && \
     apk add py3-psycopg2 \
+            py3-requests \
             py3-yaml \
             tini
 

tests/docker-compose.yml

@@ -23,7 +23,7 @@ services:
       test: [ "CMD-SHELL", "pg_controldata /var/lib/postgresql/data/ | grep -q 'in production'" ]
       interval: 5s
       timeout: 2s
-      retries: 20
+      retries: 40
     command: >
       postgres -c ssl=on
                -c ssl_cert_file='/etc/ssl/certs/ssl-cert-snakeoil.pem'

tests/run-tests.sh

@@ -6,12 +6,15 @@ versions=( $@ )
 # If we weren't given any versions, test them all
 if [ ${#versions[@]} -eq 0 ]
 then
-    versions=( 9.2 9.6 10 11 12 13 14 15 16 17 )
+    versions=( 9.2 9.4 9.6 10 11 12 13 14 15 16 17 )
 fi
 
 # Image tags to use
 declare -A images=()
 images["9.2"]='9.2'
+images["9.3"]='9.3'
+images["9.4"]='9.4'
+images["9.5"]='9.5'
 images["9.6"]='9.6-bullseye'
 images["10"]='10-bullseye'
 images["11"]='11-bookworm'