---
- name: Set architecture fact
  ansible.builtin.set_fact:
    _prometheus_arch: "{{ {'x86_64': 'amd64', 'aarch64': 'arm64', 'armv7l': 'armv7'}.get(ansible_architecture, 'amd64') }}"

- name: Get Prometheus release info from GitHub
  ansible.builtin.uri:
    url: >-
      {{ 'https://api.github.com/repos/prometheus/prometheus/releases/latest'
         if prometheus_version == ''
         else 'https://api.github.com/repos/prometheus/prometheus/releases/tags/v' + prometheus_version }}
    headers:
      Accept: "application/vnd.github.v3+json"
    return_content: true
  register: _prometheus_release

- name: Set version and download URL facts
  ansible.builtin.set_fact:
    _prometheus_version_tag: "{{ _prometheus_release.json.tag_name }}"
    _prometheus_download_url: >-
      {{ _prometheus_release.json.assets
         | selectattr('name', 'search', 'linux-' + _prometheus_arch + '.tar.gz')
         | map(attribute='browser_download_url')
         | first }}

- name: Read installed version
  ansible.builtin.slurp:
    src: "{{ prometheus_install_dir }}/.version"
  register: _prometheus_installed_raw
  ignore_errors: true
  become: true

- name: Set installed version fact
  ansible.builtin.set_fact:
    _prometheus_installed_version: >-
      {{ (_prometheus_installed_raw.content | b64decode | trim)
         if _prometheus_installed_raw is not failed else '' }}

- name: Install or upgrade Prometheus
  when: _prometheus_installed_version != _prometheus_version_tag
  block:
    - name: Download Prometheus archive
      ansible.builtin.get_url:
        url: "{{ _prometheus_download_url }}"
        dest: /tmp/prometheus.tar.gz
        mode: '0644'

    - name: Create Prometheus installation directory
      ansible.builtin.file:
        path: "{{ prometheus_install_dir }}"
        state: directory
        owner: "{{ prometheus_user }}"
        group: "{{ prometheus_group }}"
        mode: '0755'
      become: true

    - name: Extract Prometheus archive
      ansible.builtin.unarchive:
        src: /tmp/prometheus.tar.gz
        dest: "{{ prometheus_install_dir }}"
        remote_src: true
        extra_opts: [--strip-components=1]
        owner: "{{ prometheus_user }}"
        group: "{{ prometheus_group }}"
      become: true

    - name: Write installed version file
      ansible.builtin.copy:
        content: "{{ _prometheus_version_tag }}"
        dest: "{{ prometheus_install_dir }}/.version"
        owner: "{{ prometheus_user }}"
        group: "{{ prometheus_group }}"
        mode: '0644'
      become: true

    - name: Remove downloaded archive
      ansible.builtin.file:
        path: /tmp/prometheus.tar.gz
        state: absent

- name: Create Prometheus directories
  ansible.builtin.file:
    path: "{{ item }}"
    state: directory
    owner: "{{ prometheus_user }}"
    group: "{{ prometheus_group }}"
    mode: '0755'
  become: true
  loop:
    - "{{ prometheus_data_dir }}"
    - "{{ prometheus_config_dir }}"

- name: Create Prometheus systemd service
  ansible.builtin.copy:
    content: |
      [Unit]
      Description=Prometheus
      After=network-online.target
      Wants=network-online.target

      [Service]
      Type=simple
      User={{ prometheus_user }}
      Group={{ prometheus_group }}
      ExecStart={{ prometheus_install_dir }}/prometheus \
        --config.file={{ prometheus_config_dir }}/prometheus.yml \
        --storage.tsdb.path={{ prometheus_data_dir }} \
        --web.console.templates={{ prometheus_install_dir }}/consoles \
        --web.console.libraries={{ prometheus_install_dir }}/console_libraries
      Restart=on-failure
      RestartSec=5s

      [Install]
      WantedBy=multi-user.target
    dest: /etc/systemd/system/prometheus.service
    mode: '0644'
  become: true

- name: Enable and start Prometheus service
  ansible.builtin.systemd:
    name: prometheus
    enabled: "{{ prometheus_service_enabled }}"
    state: "{{ prometheus_service_state }}"
    daemon_reload: true
  become: true