refactor(nut): merge prometheus exporter into nut role

- exporter gated by nut_prometheus_exporter_enabled
- env-file config (correct NUT_EXPORTER_* vars + --web.listen-address)
- remove standalone nut_exporter role

roles/nut/README.md

@@ -82,7 +82,28 @@ journalctl -u nut-monitor -u nut-server -u 'nut-driver@*' -f
 - udev rules shipped by the `nut` package grant USB device access to the `nut`
   group only.
 
-## Companion role
+## Prometheus exporter
 
-See [`nut_exporter`](../nut_exporter/README.md) to expose Prometheus metrics
-based on the same upsd instance.
+Optionally exposes UPS metrics for Prometheus via `prometheus-nut-exporter`
+(AUR, Arch-only). Enable it:
+
+```yaml
+nut_prometheus_exporter_enabled: true
+```
+
+The exporter reuses `nut_monitor_password`, binds to
+`{{ nut_prometheus_exporter_listen_address }}` (default `127.0.0.1:9199`) and
+serves UPS metrics on `/ups_metrics`. Pair it with a Prometheus scrape job:
+
+```yaml
+prometheus_scrape_configs:
+  - job_name: 'nut'
+    metrics_path: /ups_metrics
+    static_configs:
+      - targets: ['127.0.0.1:9199']
+```
+
+```bash
+systemctl status prometheus-nut-exporter
+curl -s 'http://127.0.0.1:9199/ups_metrics' | head
+```

roles/nut/defaults/main.yml

@@ -5,7 +5,7 @@
 # UPS definition
 # --------------
 # Logical name of the UPS as referenced everywhere (ups.conf section, upsmon
-# MONITOR line, nut_exporter ?ups= query parameter).
+# MONITOR line, exporter ?ups= query parameter).
 nut_ups_name: eaton
 
 # Human-readable description (shown in upsc output).
@@ -33,7 +33,7 @@ nut_ups_maxretry: 3
 nut_upsd_listen:
   - { addr: "127.0.0.1", port: 3493 }
 
-# Local monitor user used by upsmon and nut_exporter. Password must be set.
+# Local monitor user used by upsmon and the Prometheus exporter. Password must be set.
 nut_monitor_user: monitor
 # nut_monitor_password: ""  # Intentionally undefined - role will fail if not set
 
@@ -66,3 +66,10 @@ nut_notify_script_path: /usr/local/bin/ups-notify
 # ONLINE notification can report total outage duration. Lives under /run so it
 # is cleared on reboot (stale outage state is meaningless after a reboot).
 nut_outage_state_file: /run/ups-notify-outage
+
+# Prometheus exporter (optional)
+# ------------------------------
+nut_prometheus_exporter_enabled: false
+nut_prometheus_exporter_listen_address: "127.0.0.1:9199"
+nut_prometheus_exporter_nut_server: "127.0.0.1:3493"
+nut_prometheus_exporter_nut_user: "{{ nut_monitor_user }}"

roles/nut/handlers/main.yml

@@ -13,3 +13,12 @@
   ansible.builtin.systemd:
     name: nut-monitor.service
     state: restarted
+
+- name: Reload systemd
+  ansible.builtin.systemd:
+    daemon_reload: true
+
+- name: Restart NUT exporter
+  ansible.builtin.systemd:
+    name: "{{ nut_prometheus_exporter_service }}"
+    state: restarted

roles/nut/tasks/exporter.yml

@@ -0,0 +1,32 @@
+---
+# Prometheus NUT exporter (optional, gated by nut_prometheus_exporter_enabled).
+# Installs prometheus-nut-exporter (AUR) and points it at the local upsd via
+# the unit's EnvironmentFile (/etc/conf.d/prometheus-nut-exporter).
+
+- name: Install prometheus-nut-exporter (AUR via paru)
+  ansible.builtin.command: "paru -S --noconfirm --needed {{ nut_prometheus_exporter_package }}"
+  register: _nut_prometheus_exporter_install
+  changed_when: "'there is nothing to do' not in _nut_prometheus_exporter_install.stdout | lower"
+  when: ansible_facts['os_family'] == 'Archlinux'
+
+- name: Remove legacy exporter systemd override
+  ansible.builtin.file:
+    path: "/etc/systemd/system/{{ nut_prometheus_exporter_service }}.service.d"
+    state: absent
+  notify: Reload systemd
+
+- name: Deploy exporter environment file
+  ansible.builtin.template:
+    src: nut-exporter-env.conf.j2
+    dest: "{{ nut_prometheus_exporter_env_file }}"
+    owner: root
+    group: root
+    mode: "0600"
+  notify: Restart NUT exporter
+
+- name: Enable and start exporter
+  ansible.builtin.systemd:
+    name: "{{ nut_prometheus_exporter_service }}"
+    enabled: true
+    state: started
+    daemon_reload: true

roles/nut/tasks/main.yml

@@ -95,3 +95,7 @@
     enabled: true
     state: started
   loop: "{{ nut_services }}"
+
+- name: Deploy Prometheus NUT exporter
+  ansible.builtin.include_tasks: exporter.yml
+  when: nut_prometheus_exporter_enabled | bool

roles/nut/templates/nut-exporter-env.conf.j2

@@ -0,0 +1,5 @@
+# Managed by Ansible - DO NOT EDIT MANUALLY
+# EnvironmentFile for prometheus-nut-exporter (read by the systemd unit via
+# $NUT_EXPORTER_ARGS). The password has no flag, so it is passed as an env var.
+NUT_EXPORTER_ARGS="--web.listen-address={{ nut_prometheus_exporter_listen_address }} --nut.server={{ nut_prometheus_exporter_nut_server.split(':')[0] }} --nut.serverport={{ nut_prometheus_exporter_nut_server.split(':')[1] }} --nut.username={{ nut_prometheus_exporter_nut_user }}"
+NUT_EXPORTER_PASSWORD="{{ nut_monitor_password }}"

roles/nut/vars/archlinux.yml

@@ -7,3 +7,8 @@ nut_services:
   - nut-driver-enumerator.service
   - nut-server.service
   - nut-monitor.service
+
+# Prometheus exporter (AUR)
+nut_prometheus_exporter_package: prometheus-nut-exporter
+nut_prometheus_exporter_service: prometheus-nut-exporter
+nut_prometheus_exporter_env_file: /etc/conf.d/prometheus-nut-exporter