ansible/roles/prometheus-node-exporter/tasks/main.yml

---
- name: Use a newer version of Node exporter for ubuntu 20.04
  block:
    - name: Set the default release
      lineinfile:
        path: /etc/apt/apt.conf.d/01-vendor-ubuntu
        regexp: '^APT::Default-Release '
        line: "APT::Default-Release \"{{ ansible_facts['lsb']['codename'] }}\";"
    - name: Pin node exporter
      copy:
        dest: /etc/apt/preferences.d/pin-prometheus-node-exporter
        content: |
          Package: prometheus-node-exporter
          Pin: release n={{ ansible_facts['lsb']['codename'] }}
          Pin-Priority: -10
          
          Package: prometheus-node-exporter
          Pin: release n=groovy
          Pin-Priority: 900
    - name: Add the repo from groovy
      apt_repository:
        repo: deb http://fr.archive.ubuntu.com/ubuntu groovy universe
        state: present
  when: ansible_facts['lsb']['id'] == 'Ubuntu' and ansible_facts['lsb']['codename'] == 'focal'

- name: Install Prometheus Node exporter
  apt:
    name:
      - prometheus-node-exporter
      - prometheus-node-exporter-collectors
    state: latest
    update_cache: true
    install_recommends: false  # Do not install smartmontools
  register: apt_result
  retries: 3
  until: apt_result is succeeded

- name: Ensure /etc/node_exporter exist
  file:
    path: /etc/node_exporter
    state: directory
    group: prometheus
    owner: prometheus
    mode: u=rwx,g=rx,o=rx

- name: Copy the config folder
  template:
    src: config.yaml
    dest: /etc/node_exporter/config.yaml
    group: prometheus
    owner: prometheus
    mode: u=rw,g=r,o=r
  notify: Restart prometheus-node-exporter

- name: Generate certificate
  include_role:
    name: generate-cert
  vars:
    directory: /etc/node_exporter/
    cname: "node-exp-{{ lan_address }}"
    owner: prometheus
    group: prometheus
    key_mode: u=rw,g=,o=
    subject_alt_name: "IP:{{ lan_address }}"
# Need an equivalent to notify here

- name: Copy the CA cert
  copy:
    content: "{{ ca_cert }}"
    dest: /etc/node_exporter/ca.crt
  notify: Restart prometheus-node-exporter

- name: Setup the arguments for node-exporter
  template:
    src: prometheus-node-exporter
    dest: /etc/default/prometheus-node-exporter
    owner: root
    group: root
    mode: u=rw,g=r,o=r
  notify: Restart prometheus-node-exporter
  vars:
    args:
      - name: web.listen-address
        value: "{{ lan_address }}:9100"
      - name: web.config
        value: /etc/node_exporter/config.yaml

# Add the node to the server targets

- name: Get the list of targets of the server
  slurp:
    src: /etc/prometheus/node-targets.json
  register: server_target_file
  delegate_to: "{{ appointed_prometheus_server }}"

- name: Set target variable
  set_fact:
    server_target: "{{ server_target_file['content'] | b64decode | from_json }}"

- name: Register the node to the prometheus server
  block:
    - name: Add the node to the targets
      set_fact:
        new_server_target: "[{{ server_target[0] | combine({'targets': [lan_address + '/' + ansible_facts['nodename']]}, list_merge='append_rp') }}]"
    
    - name: Put the new target list
      copy:
        content: "{{ new_server_target | to_nice_json }}"
        dest: /etc/prometheus/node-targets.json
      delegate_to: "{{ appointed_prometheus_server }}"
  when: (lan_address + '/' + ansible_facts['nodename']) not in server_target.0.targets