zabbix-agent: add PostgreSQL DB size monitoring

Add monitoring for our PostgreSQL DB size using a similiar construct as
the MySQL DB size monitoring with a perl script.

host_vars/apollo.archlinux.org

@@ -30,6 +30,7 @@ zabbix_agent_templates:
   - Template App SMTP Service
   - Template App SSH Service
   - Template App Zabbix Server
+  - Template App PostgreSQL
 
 zabbix_agent_host_groups:
   - Linux servers

host_vars/nymeria.archlinux.org

@@ -17,6 +17,7 @@ archweb_version: release_2018-11-23
 
 zabbix_agent_templates:
   - Template OS Linux
+  - Template App PostgreSQL
 
 configure_firewall: true
 ansible_python_interpreter: /usr/bin/python3.7

host_vars/soyuz.archlinux.org

@@ -15,6 +15,7 @@ zabbix_agent_templates:
   - Template OS Linux
   - Template App Borg Backup
   - Template App Syncrepo
+  - Template App PostgreSQL
 
 configure_firewall: true
 

roles/zabbix-agent/files/postgresql-dbsize-stats.pl

+#!/usr/bin/env perl
+use strict;
+use warnings;
+
+use DBI;
+use JSON;
+
+my $mode = $ARGV[0];
+my $dbname = $ARGV[1];
+
+if (!($mode eq "dbsize" or $mode eq "discover")) {
+	print STDERR "mode is not dbsize or discover\n";
+	die;
+}
+
+if ($mode eq "dbsize" and not defined $dbname) {
+	print STDERR "dbsize requires dbname to be defined\n";
+	die;
+}
+
+my $db = DBI->connect("DBI:Pg:");
+
+if ($mode eq "dbsize") {
+	print encode_json($db->selectrow_hashref("SELECT pg_database_size(?) AS dbsize;", undef, $dbname));
+} elsif ($mode eq "discover") {
+	print encode_json({
+		data => $db->selectall_arrayref("SELECT datname \"{#DATNAME}\" FROM pg_database;", {Slice => {}})
+	});
+} else {
+	die "unhandled mode";
+}

roles/zabbix-agent/tasks/main.yml

@@ -12,7 +12,7 @@
   when: "'nginx' in group_names"
 
 - name: install mysql userstats monitoring packages
-  pacman: name=perl-dbi,perl-dbd-mysql,perl-json
+  pacman: name=perl-dbi,perl-dbd-mysql,perl-dbd-pg,perl-json
   when: "'mysql-servers' in group_names"
 
 - file: path=/etc/zabbix state=directory owner=root group=root mode=755
@@ -71,6 +71,7 @@
     - systemd-discover-accounting-units.py
     - zabbix-borg-timestamps.pl
     - mysql-dbsize-stats.pl
+    - postgresql-dbsize-stats.pl
 
 - name: Install helper scripts
   copy: src=nginx-zabbix.pl dest=/usr/local/bin/nginx-zabbix.pl mode=0755 owner=root group=root

roles/zabbix-agent/templates/zabbix-agent-sudoers.conf.j2

 zabbix-agent ALL=(root) NOPASSWD: /usr/local/bin/borg list --json --format {start}{end} --sort-by timestamp --last 1, /usr/local/bin/mysql-dbsize-stats.pl
+zabbix-agent ALL=(postgres) NOPASSWD: /usr/local/bin/postgresql-dbsize-stats.pl

roles/zabbix-agent/templates/zabbix_agentd.conf

@@ -17,6 +17,9 @@ UserParameter=mysql.userstats_discover,/usr/local/bin/mysql-user-stats.pl "/etc/
 UserParameter=mysql.dbsize[*],sudo /usr/local/bin/mysql-dbsize-stats.pl "/root/.my.cnf" dbsize '$1'
 UserParameter=mysql.dbsize_discover,sudo /usr/local/bin/mysql-dbsize-stats.pl "/root/.my.cnf" discover
 
+UserParameter=postgresql.dbsize[*],sudo -u postgres /usr/local/bin/postgresql-dbsize-stats.pl dbsize '$1'
+UserParameter=postgresql.dbsize_discover,sudo -u postgres /usr/local/bin/postgresql-dbsize-stats.pl discover
+
 UserParameter=systemd.unit.is-active[*],systemctl is-active --quiet '$1' && echo 1 || echo 0
 UserParameter=systemd.unit.is-failed[*],systemctl is-failed --quiet '$1' && echo 1 || echo 0
 UserParameter=systemd.unit.is-enabled[*],systemctl is-enabled --quiet '$1' && echo 1 || echo 0