---
# Both exporters listen on all addresses; host_firewall limits who reaches them.
# Its recommends (smartmontools, nvme-cli, ipmitool) start units that fail on hosts without such hardware.
- name: Install the node exporter
  ansible.builtin.apt:
    name: prometheus-node-exporter
    install_recommends: false
    state: present

- name: Enable the node exporter
  ansible.builtin.systemd:
    name: prometheus-node-exporter
    enabled: true
    state: started
  # Check mode does not install the package.
  ignore_errors: "{{ ansible_check_mode }}"

- name: Install the smartctl exporter
  when: host_exporters_smart
  block:
    - name: Look for an existing backports source
      ansible.builtin.shell: >-
        grep -rEqs '^[^#]*{{ ansible_distribution_release }}-backports'
        --include='*.list' --include='*.sources' --exclude=host-exporters-backports.sources /etc/apt
      register: host_exporters_backports
      changed_when: false
      failed_when: host_exporters_backports.rc > 1
      check_mode: false

    # Backports stay at priority 100, so only packages named with default_release come from there.
    - name: Add the backports source
      ansible.builtin.copy:
        dest: /etc/apt/sources.list.d/host-exporters-backports.sources
        mode: "0644"
        content: |
          Types: deb
          URIs: http://deb.debian.org/debian
          Suites: {{ ansible_distribution_release }}-backports
          Components: main
          Signed-By: /usr/share/keyrings/debian-archive-keyring.gpg
      register: host_exporters_source
      when: host_exporters_backports.rc == 1

    # The module rejects default_release while the release is missing from its package cache.
    - name: Look for the backports release in the package lists
      ansible.builtin.shell: apt-cache policy | grep -q 'n={{ ansible_distribution_release }}-backports'
      register: host_exporters_lists
      changed_when: false
      failed_when: false
      check_mode: false

    - name: Refresh the package lists for the backports source
      ansible.builtin.apt:
        update_cache: true
      when: host_exporters_lists.rc != 0

    - name: Install the smartctl exporter from backports
      ansible.builtin.apt:
        name: prometheus-smartctl-exporter
        default_release: "{{ ansible_distribution_release }}-backports"
        state: present
      # Check mode does not write the backports source.
      ignore_errors: "{{ ansible_check_mode }}"

    # The packaged unit runs as root, which smartctl needs for the disks.
    - name: Enable the smartctl exporter
      ansible.builtin.systemd:
        name: smartctl_exporter
        enabled: true
        state: started
      ignore_errors: "{{ ansible_check_mode }}"