Add monitoring

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

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

@@ -0,0 +1,10 @@
+---
+- name: Restart nginx
+  service:
+    name: nginx
+    state: restarted
+
+- name: Restart prometheus-nginx-exporter
+  service:
+    name: prometheus-nginx-exporter
+    state: restarted

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

@@ -0,0 +1,33 @@
+---
+- name: Install prometheus-nginx-exporter
+  apt:
+    update_cache: true
+    name:
+      - nginx  # Nginx may be not already installed
+      - prometheus-nginx-exporter
+  register: apt_result
+  retries: 3
+  until: apt_result is succeeded
+
+- name: Make prometheus-nginx-exporter listen on adm only
+  lineinfile:
+    path: /etc/default/prometheus-nginx-exporter
+    regexp: '^ARGS='
+    line: |
+      ARGS="-web.listen-address={{ prometheus_nginx_exporter.listen_addr }}:9117 -nginx.scrape-uri=http://[::1]:6424/stub_status"
+  notify:
+    - Restart nginx
+    - Restart prometheus-nginx-exporter
+
+- name: Configure nginx
+  template:
+    src: nginx/status.j2
+    dest: /etc/nginx/sites-available/status
+  notify: Restart nginx
+
+- name: Activate nginx site
+  file:
+    src: /etc/nginx/sites-available/status
+    dest: /etc/nginx/sites-enabled/status
+    state: link
+  notify: Restart nginx

roles/prometheus-nginx-exporter/templates/nginx/status.j2

@@ -0,0 +1,8 @@
+{{ ansible_header | comment }}
+
+server {
+    listen [::1]:6424;
+    location = /stub_status {
+        stub_status;
+    }
+}