prometheus: monitor geomirror nameservers

Ensure all the nameservers serving the geo.mirror.pkgbuild.com subzone
are working and respond with a valid resource record to A/AAAA queries.

roles/prometheus/defaults/main.yml

@@ -75,6 +75,8 @@ blackbox_targets:
   smtp_starttls:
     - mail.archlinux.org:25
     - lists.archlinux.org:25
+  dns_geomirror_a: "{{ groups['geo_mirrors'] + ['mirror.pkgbuild.com'] }}"
+  dns_geomirror_aaaa: "{{ groups['geo_mirrors'] + ['mirror.pkgbuild.com'] }}"
 matrix_metrics_endpoints:
   - homeserver
   - appservice

roles/prometheus_exporters/handlers/main.yml

+---
+
+- name: reload blackbox exporter
+  service: name=prometheus-blackbox-exporter state=reloaded

roles/prometheus_exporters/tasks/main.yml

@@ -124,7 +124,8 @@
   systemd: name=prometheus-fail2ban-textcollector.timer enabled=yes daemon_reload=yes state=started
 
 - name: install blackbox exporter configuration
-  copy: src=blackbox.yml dest=/etc/prometheus/blackbox.yml owner=root group=root mode=0644
+  template: src=blackbox.yml.j2 dest=/etc/prometheus/blackbox.yml owner=root group=root mode=0644
+  notify: reload blackbox exporter
   when: "'prometheus' in group_names"
 
 - name: install rebuilderd textcollector service

roles/prometheus_exporters/files/blackbox.yml → roles/prometheus_exporters/templates/blackbox.yml.j2

@@ -24,3 +24,23 @@ modules:
         - send: "EHLO prober\r"
         - expect: "^250"
         - send: "QUIT\r"
+  dns_geomirror_a:
+    prober: dns
+    timeout: 5s
+    dns:
+      query_name: geo.mirror.pkgbuild.com
+      query_type: A
+      preferred_ip_protocol: ip4
+      validate_answer_rrs:
+        fail_if_not_matches_regexp:
+          - geo\.mirror\.pkgbuild\.com\.\t.*\tIN\tA\t({{ groups['geo_mirrors'] | map('extract', hostvars, ['ipv4_address']) | join('|') | replace('.', '\.') }})
+  dns_geomirror_aaaa:
+    prober: dns
+    timeout: 5s
+    dns:
+      query_name: geo.mirror.pkgbuild.com
+      query_type: AAAA
+      preferred_ip_protocol: ip6
+      validate_answer_rrs:
+        fail_if_not_matches_regexp:
+          - geo\.mirror\.pkgbuild\.com\.\t.*\tIN\tAAAA\t({{ groups['geo_mirrors'] | map('extract', hostvars, ['ipv6_address']) | join('|') }})