ansible-collection-prometheus/roles/prometheus/tasks/preflight.yml

---
- name: Assert usage of systemd as an init system
  ansible.builtin.assert:
    that: ansible_service_mgr == 'systemd'
    msg: "This module only works with systemd"

- name: Get systemd version
  ansible.builtin.command: systemctl --version
  changed_when: false
  check_mode: false
  register: __systemd_version
  tags:
    - skip_ansible_lint

- name: Set systemd version fact
  ansible.builtin.set_fact:
    prometheus_systemd_version: "{{ __systemd_version.stdout_lines[0].split(' ')[-1] }}"

- name: Assert no duplicate config flags
  ansible.builtin.assert:
    that:
      - prometheus_config_flags_extra['config.file'] is not defined
      - prometheus_config_flags_extra['storage.tsdb.path'] is not defined
      - prometheus_config_flags_extra['storage.local.path'] is not defined
      - prometheus_config_flags_extra['web.listen-address'] is not defined
      - prometheus_config_flags_extra['web.external-url'] is not defined
    msg: "Detected duplicate configuration entry. Please check your ansible variables and role README.md."

- name: Assert external_labels aren't configured twice
  ansible.builtin.assert:
    that: prometheus_global.external_labels is not defined
    msg: "Use prometheus_external_labels to define external labels"

- name: Set prometheus external metrics path
  ansible.builtin.set_fact:
    prometheus_metrics_path: "/{{ (prometheus_web_external_url + '/metrics') | regex_replace('^(.*://)?(.*?)/') }}"

- name: Fail when prometheus_config_flags_extra duplicates parameters set by other variables
  ansible.builtin.fail:
    msg: >
      Whooops. You are duplicating configuration. Please look at your prometheus_config_flags_extra
      and check against other variables in defaults/main.yml
  with_items:
    - 'storage.tsdb.retention'
    - 'storage.tsdb.path'
    - 'storage.local.retention'
    - 'storage.local.path'
    - 'config.file'
    - 'web.listen-address'
    - 'web.external-url'
  when: item in prometheus_config_flags_extra.keys()

- name: Get all file_sd files from scrape_configs
  ansible.builtin.set_fact:
    file_sd_files: "{{ prometheus_scrape_configs | json_query('[*][].file_sd_configs[*][].files[]') }}"

- name: Fail when file_sd targets are not defined in scrape_configs
  ansible.builtin.fail:
    msg: >
      Oh, snap! `{{ item.key }}` couldn't be found in your scrape configs. Please ensure you provided
      all targets from prometheus_targets in prometheus_scrape_configs
  when: not prometheus_config_dir + "/file_sd/" + item.key + ".yml" in file_sd_files
  #  when: not item | basename | splitext | difference(['.yml']) | join('') in prometheus_targets.keys()
  with_dict: "{{ prometheus_targets }}"

- name: Alert when prometheus_alertmanager_config is empty, but prometheus_alert_rules is specified
  ansible.builtin.debug:
    msg: >
      No alertmanager configuration was specified. If you want your alerts to be sent make sure to
      specify a prometheus_alertmanager_config in defaults/main.yml.
  when:
    - prometheus_alertmanager_config == []
    - prometheus_alert_rules != []

- name: Discover latest version
  when:
    - prometheus_version == "latest"
    - prometheus_binary_local_dir | length == 0
    - not prometheus_skip_install
  block:

    - name: Get latest release
      ansible.builtin.uri:
        url: "https://api.github.com/repos/prometheus/prometheus/releases/latest"
        method: GET
        return_content: true
        status_code: 200
        body_format: json
        validate_certs: false
        ansible.builtin.user: "{{ lookup('env', 'GH_USER') | default(omit) }}"
        password: "{{ lookup('env', 'GH_TOKEN') | default(omit) }}"
      no_log: "{{ not lookup('env', 'ANSIBLE_DEBUG') | bool }}"
      register: _latest_release
      until: _latest_release.status == 200
      retries: 5

    - name: "Set prometheus version to {{ _latest_release.json.tag_name[1:] }}"
      ansible.builtin.set_fact:
        prometheus_version: "{{ _latest_release.json.tag_name[1:] }}"

- name: Get prometheus binary checksum
  delegate_to: localhost
  when:
    - prometheus_binary_local_dir | length == 0
    - not prometheus_skip_install
  block:
    - name: "Get checksum list"
      ansible.builtin.set_fact:
        __prometheus_checksums: "{{ lookup('url', 'https://github.com/prometheus/prometheus/releases/download/v' + prometheus_version + '/sha256sums.txt', wantlist=True) | list }}"
      run_once: true

    - name: "Get checksum for {{ go_arch }}"
      ansible.builtin.set_fact:
        __prometheus_checksum: "{{ item.split(' ')[0] }}"
      with_items: "{{ __prometheus_checksums }}"
      when:
        - "('linux-' + go_arch + '.tar.gz') in item"