Add support for NUT (EATON inverter)

roles/nut_exporter/README.md

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+# nut_exporter — Prometheus exporter for NUT
+
+Scrapes a local `upsd` and exposes UPS metrics for Prometheus.
+
+## Supported distributions
+
+- Arch Linux (AUR package `prometheus-nut-exporter`, installed via `paru`)
+
+Debian/Ubuntu is not packaged upstream — add it on demand.
+
+## Configuration
+
+See [defaults/main.yml](defaults/main.yml).
+
+Required:
+
+```yaml
+nut_exporter_nut_password: "<same as nut_monitor_password>"
+```
+
+Optional:
+
+```yaml
+nut_exporter_listen_address: "127.0.0.1:9199"
+nut_exporter_nut_server: "127.0.0.1:3493"
+nut_exporter_nut_user: monitor
+```
+
+## Pairing with Prometheus
+
+Typical scrape config (target uses the multi-target pattern: the exporter
+queries a remote upsd specified in the URL parameters):
+
+```yaml
+prometheus_scrape_configs:
+  - job_name: 'nut'
+    metrics_path: /nut
+    static_configs:
+      - targets: ['eaton@localhost']  # ups@host syntax
+    relabel_configs:
+      - source_labels: [__address__]
+        target_label: __param_target
+      - source_labels: [__param_target]
+        target_label: instance
+      - target_label: __address__
+        replacement: 127.0.0.1:9199
+```
+
+## Operations
+
+```bash
+systemctl status prometheus-nut-exporter
+curl -s 'http://127.0.0.1:9199/nut?target=localhost&ups=eaton' | head
+journalctl -u prometheus-nut-exporter -f
+```
+
+## Dependencies
+
+Requires the [`nut`](../nut/README.md) role (or any other running upsd) on the
+same host.

roles/nut_exporter/defaults/main.yml

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+---
+# Prometheus NUT exporter configuration
+
+# Address the exporter listens on.
+nut_exporter_listen_address: "127.0.0.1:9199"
+
+# upsd server to connect to (kept local — exporter sits next to upsd).
+nut_exporter_nut_server: "127.0.0.1:3493"
+
+# Credentials used to log into upsd. These should match the upsd user defined
+# by the nut role (nut_monitor_user / nut_monitor_password).
+nut_exporter_nut_user: "{{ nut_monitor_user | default('monitor') }}"
+# nut_exporter_nut_password: ""  # Inherits nut_monitor_password by default

roles/nut_exporter/handlers/main.yml

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+---
+- name: Reload systemd
+  ansible.builtin.systemd:
+    daemon_reload: true
+
+- name: Restart nut_exporter
+  ansible.builtin.systemd:
+    name: "{{ nut_exporter_service }}"
+    state: restarted

roles/nut_exporter/meta/main.yml

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+---
+dependencies: []

roles/nut_exporter/tasks/main.yml

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+---
+- name: Validate required configuration
+  ansible.builtin.assert:
+    that:
+      - nut_exporter_nut_password is defined
+      - nut_exporter_nut_password | length >= 12
+    fail_msg: |
+      nut_exporter_nut_password (>=12 chars) is required.
+      Usually set to the same value as nut_monitor_password.
+
+- name: Load OS-specific variables
+  ansible.builtin.include_vars: "{{ item }}"
+  with_first_found:
+    - "{{ ansible_facts['os_family'] }}.yml"
+
+- name: Install prometheus-nut-exporter (AUR via paru)
+  ansible.builtin.command: "paru -S --noconfirm --needed {{ nut_exporter_package }}"
+  register: nut_exporter_install
+  changed_when: "'there is nothing to do' not in nut_exporter_install.stdout | lower"
+  when: ansible_facts['os_family'] == 'Archlinux'
+
+- name: Ensure systemd override directory exists
+  ansible.builtin.file:
+    path: "{{ nut_exporter_override_dir }}"
+    state: directory
+    owner: root
+    group: root
+    mode: "0755"
+
+- name: Deploy systemd override (listen address + upsd credentials)
+  ansible.builtin.template:
+    src: override.conf.j2
+    dest: "{{ nut_exporter_override_dir }}/override.conf"
+    owner: root
+    group: root
+    mode: "0640"
+  notify:
+    - Reload systemd
+    - Restart nut_exporter
+
+- name: Enable and start nut_exporter
+  ansible.builtin.systemd:
+    name: "{{ nut_exporter_service }}"
+    enabled: true
+    state: started
+    daemon_reload: true

roles/nut_exporter/templates/override.conf.j2

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+# Managed by Ansible - DO NOT EDIT MANUALLY
+# Override for prometheus-nut-exporter to inject listen address and upsd
+# credentials. The exporter reads NUT_EXPORTER_* env vars at startup.
+
+[Service]
+Environment="HTTP_LISTEN_ADDRESS={{ nut_exporter_listen_address }}"
+Environment="NUT_EXPORTER_SERVER={{ nut_exporter_nut_server.split(':')[0] }}"
+Environment="NUT_EXPORTER_PORT={{ nut_exporter_nut_server.split(':')[1] }}"
+Environment="NUT_EXPORTER_USERNAME={{ nut_exporter_nut_user }}"
+Environment="NUT_EXPORTER_PASSWORD={{ nut_exporter_nut_password }}"

roles/nut_exporter/vars/archlinux.yml

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+---
+nut_exporter_package: prometheus-nut-exporter
+nut_exporter_service: prometheus-nut-exporter.service
+nut_exporter_user: nut-exporter
+nut_exporter_group: nut-exporter
+nut_exporter_override_dir: /etc/systemd/system/prometheus-nut-exporter.service.d