---
- name: "Create Alertmanager system group"
  ansible.builtin.group:
    name: "{{ alertmanager_user }}"
    system: true
    state: present

- name: "Create Alertmanager system user"
  ansible.builtin.user:
    name: "{{ alertmanager_user }}"
    group: "{{ alertmanager_group }}"
    system: true
    shell: "/sbin/nologin"
    create_home: false
    state: present

- name: "Install Alertmanager from binary"
  block:
    - name: "Check Alertmanager version"
      changed_when: false
      ansible.builtin.command:
        cmd: "alertmanager --version"
      register: alertmanager_ver

    - name: "Assert version correctness"
      ansible.builtin.assert:
        that: "alertmanager_ver.stdout is regex('{{ alertmanager_version }}')"
        success_msg: "alertmanager version {{ alertmanager_version }} is installed and working"
        fail_msg: "alertmanager version {{ alertmanager_version }} is not installed or not working correctly"

  rescue:
    - name: "Create Alertmanager directories '{{ item }}'"
      ansible.builtin.file:
        path: "{{ item }}"
        state: directory
        owner: "{{ alertmanager_user }}"
        group: "{{ alertmanager_group }}"
        mode: "0755"
      with_items:
        - "{{ config_dir }}"
        - "{{ alertmanager_dir }}"
        - "{{ storage_dir }}"

    - name: "Download Alertmanager binary"
      ansible.builtin.get_url:
        url: "https://github.com/prometheus/alertmanager/releases/download/v{{ alertmanager_version }}/\
              alertmanager-{{ alertmanager_version }}.linux-amd64.tar.gz"
        dest: "/tmp/alertmanager-{{ alertmanager_version }}.linux-amd64.tar.gz"
        owner: "{{ alertmanager_user }}"
        group: "{{ alertmanager_group }}"
        mode: "0644"

    - name: "Unpack Alertmanager binaries"
      notify: "(Re)start and enable Alertmanager"
      ansible.builtin.unarchive:
        src: "/tmp/alertmanager-{{ alertmanager_version }}.linux-amd64.tar.gz"
        dest: "{{ alertmanager_dir }}"
        creates: "{{ alertmanager_dir }}/alertmanager-{{ alertmanager_version }}.linux-amd64"
        remote_src: true

    - name: "Cleanup downloaded file"
      ansible.builtin.file:
        path: "/tmp/alertmanager-{{ alertmanager_version }}.linux-amd64.tar.gz"
        state: absent

    - name: "Move official alertmanager and amtool binaries"
      ansible.builtin.copy:
        src: "{{ alertmanager_dir }}/alertmanager-{{ alertmanager_version }}.linux-amd64/{{ item }}"
        dest: "/usr/local/bin/{{ item }}"
        mode: "0755"
        owner: "{{ alertmanager_user }}"
        group: "{{ alertmanager_group }}"
        remote_src: true
      with_items:
        - alertmanager
        - amtool


- name: "Create systemd service unit"
  ansible.builtin.template:
    src: alertmanager.service.j2
    dest: /etc/systemd/system/alertmanager.service
    owner: "{{ alertmanager_user }}"
    group: "{{ alertmanager_group }}"
    mode: "0660"