[postfix] Add Prometheus exporter

Signed-off-by: Yohann D'ANELLO <ynerant@crans.org>

host_vars/fyre.adm.crans.org.yml

@@ -119,6 +119,21 @@ loc_prometheus:
             target_label: __address__
             replacement: '$1:9119'
 
+  postfix:
+    config:
+      - job_name: postfix
+        file_sd_configs:
+          - files:
+              - '/etc/prometheus/targets/postfix.json'
+        relabel_configs:
+          - source_labels: [__address__]
+            target_label: __param_target
+          - source_labels: [__param_target]
+            target_label: instance
+          - source_labels: [__param_target]
+            target_label: __address__
+            replacement: '$1:9154'
+
   mtail:
     config:
       - job_name: mtail

plays/monitoring.yml

@@ -62,6 +62,13 @@
   roles:
     - prometheus-bind-exporter
 
+# Monitor Postfix metrics
+- hosts: postfix
+  vars:
+    prometheus_postfix_exporter: "{{ glob_prometheus_postfix_exporter | default({}) | combine(loc_prometheus_postfix_exporter | default({})) }}"
+  roles:
+    - prometheus-postfix-exporter
+
 # Monitor mailq with a special text exporter
 # - hosts: redisdead.adm.crans.org
 #   roles: ["prometheus-node-exporter-postfix"]

roles/prometheus-postfix-exporter/handlers/main.yml

@@ -0,0 +1,5 @@
+---
+- name: Restart prometheus-postfix-exporter
+  service:
+    name: prometheus-postfix-exporter
+    state: restarted

roles/prometheus-postfix-exporter/tasks/main.yml

@@ -0,0 +1,16 @@
+---
+- name: Install Prometheus postfix-exporter
+  apt:
+    update_cache: true
+    name: prometheus-postfix-exporter
+  register: apt_result
+  retries: 3
+  until: apt_result is succeeded
+
+- name: Make Prometheus postfix-exporter listen on adm only
+  lineinfile:
+    path: /etc/default/prometheus-postfix-exporter
+    regexp: ^ARGS=
+    line: |
+      ARGS="--web.listen-address={{ prometheus_postfix_exporter.listen_addr }}:9154"
+  notify: Restart prometheus-postfix-exporter