Add prometheus exporter for postfix and option postfix.metrics_address

defaults/main.yml

@@ -44,3 +44,4 @@ postfix:
   add_header_checks: []
   smtpd_milters: []
   non_smtpd_milters: []
+  metrics_address: "127.0.0.1:9154"

handlers/main.yml

@@ -3,3 +3,6 @@
 
 - name: restart saslauthd
   service: name=saslauthd state=restarted
+
+- name: restart prometheus-postfix-exporter
+  service: name=prometheus-postfix-exporter state=restarted

tasks/main.yml

@@ -3,6 +3,21 @@
     pkg:
       - postfix
 
+- name: install prometheus postfix exporter
+  apt:
+    pkg:
+    - prometheus-postfix-exporter
+
+- name: configure prometheus postfix exporter
+  template:
+    src: prometheus-postfix-exporter.j2
+    dest: /etc/default/prometheus-postfix-exporter
+    owner: root
+    group: root
+    mode: 0644
+  notify:
+  - restart prometheus-postfix-exporter
+
 - name: Install and setup utilities for LDAP
   when: postfix.ldap.enable
   block:

templates/prometheus-postfix-exporter.j2

@@ -0,0 +1,15 @@
+# Private log file from Postfix to read and truncate. Configured in
+# /etc/rsyslog.d/prometheus-postfix-exporter.conf
+POSTFIXLOGFILE=/var/lib/prometheus/postfix-exporter/mail.log
+
+# Extra arguments for the daemon.
+ARGS='--web.listen-address {{ postfix.metrics_address }}'
+
+# Prometheus-postfix-exporter supports the following options:
+#  --postfix.showq_path string
+#        Path at which Postfix places its showq socket.
+#        (default "/var/spool/postfix/public/showq")
+#  --web.listen-address string
+#        Address to listen on for web interface and telemetry. (default ":9154")
+#  --web.telemetry-path string
+#        Path under which to expose metrics. (default "/metrics")