---
# Install and configure systemd_exporter for Prometheus monitoring.
# Downloads the binary from GitHub releases and deploys a systemd service.
# Linux only — systemd_exporter has no FreeBSD equivalent.

- name: Create systemd_exporter group
  ansible.builtin.group:
    name: "{{ systemd_exporter_group }}"
    system: true
    state: present

- name: Create systemd_exporter user
  ansible.builtin.user:
    name: "{{ systemd_exporter_user }}"
    group: "{{ systemd_exporter_group }}"
    system: true
    shell: /usr/sbin/nologin
    create_home: false

- name: Check if systemd_exporter binary exists
  ansible.builtin.stat:
    path: /usr/local/bin/systemd_exporter
  register: systemd_exporter_bin

- name: Get installed version
  ansible.builtin.command: /usr/local/bin/systemd_exporter --version
  register: systemd_exporter_installed_version
  changed_when: false
  failed_when: false
  when: systemd_exporter_bin.stat.exists

- name: Set architecture fact
  ansible.builtin.set_fact:
    systemd_exporter_arch: >-
      {{ ansible_architecture
         | regex_replace('x86_64', 'amd64')
         | regex_replace('aarch64', 'arm64') }}

- name: Set release and URL facts
  ansible.builtin.set_fact:
    systemd_exporter_release: >-
      systemd_exporter-{{ systemd_exporter_version }}.linux-{{ systemd_exporter_arch }}
    systemd_exporter_base_url: >-
      https://github.com/prometheus-community/systemd_exporter

- name: Download and install systemd_exporter
  when: >-
    not systemd_exporter_bin.stat.exists or
    systemd_exporter_version not in
    (systemd_exporter_installed_version.stdout | default(''))
  block:
    - name: Download systemd_exporter tarball
      ansible.builtin.get_url:
        url: >-
          {{ systemd_exporter_base_url }}/releases/download/v{{
          systemd_exporter_version }}/{{
          systemd_exporter_release }}.tar.gz
        dest: /tmp/systemd_exporter.tar.gz
        mode: '0644'

    - name: Extract systemd_exporter binary
      ansible.builtin.unarchive:
        src: /tmp/systemd_exporter.tar.gz
        dest: /tmp
        remote_src: true

    - name: Install systemd_exporter binary
      ansible.builtin.copy:
        src: "/tmp/{{ systemd_exporter_release }}/systemd_exporter"
        dest: /usr/local/bin/systemd_exporter
        mode: '0755'
        owner: root
        group: root
        remote_src: true
      notify: Restart systemd_exporter

    - name: Clean up tarball
      ansible.builtin.file:
        path: "{{ item }}"
        state: absent
      loop:
        - /tmp/systemd_exporter.tar.gz
        - "/tmp/{{ systemd_exporter_release }}"

- name: Deploy systemd_exporter service file
  ansible.builtin.template:
    src: systemd_exporter.service.j2
    dest: /etc/systemd/system/systemd_exporter.service
    mode: '0644'
  notify:
    - Reload systemd
    - Restart systemd_exporter

- name: Enable and start systemd_exporter
  ansible.builtin.service:
    name: systemd_exporter
    state: started
    enabled: true