matrix-docker-ansible-deploy/roles/custom/matrix-prometheus-node-exporter/tasks/inject_into_nginx_proxy.yml

---

- name: Fail if matrix-nginx-proxy role already executed
  ansible.builtin.fail:
    msg: >-
      Trying to append node-exporter's reverse-proxying configuration to matrix-nginx-proxy,
      but it's pointless since the matrix-nginx-proxy role had already executed.
      To fix this, please change the order of roles in your playbook,
      so that the matrix-nginx-proxy role would run after the matrix-prometheus-node-exporter role.
  when: matrix_nginx_proxy_role_executed | default(False) | bool

- name: Generate node-exporter metrics proxying configuration for matrix-nginx-proxy (matrix.DOMAIN/metrics/node-exporter)
  ansible.builtin.set_fact:
    matrix_prometheus_node_exporter_nginx_metrics_configuration_block: |
      location /metrics/node-exporter {
        {% if matrix_nginx_proxy_enabled | default(False) %}
          {# Use the embedded DNS resolver in Docker containers to discover the service #}
          resolver 127.0.0.11 valid=5s;
          set $backend "matrix-prometheus-node-exporter:9100";
          proxy_pass http://$backend/metrics;
        {% elif matrix_prometheus_node_exporter_matrix_nginx_proxy_not_enabled_proxy_pass_host != '' %}
          proxy_pass http://{{ matrix_prometheus_node_exporter_matrix_nginx_proxy_not_enabled_proxy_pass_host }}/metrics;
        {% else %}
          return 404 "matrix-nginx-proxy is disabled and no host port was bound to the container, so metrics are unavailable";
        {% endif %}
      }

- name: Register node-exporter metrics proxying configuration with matrix-nginx-proxy (matrix.DOMAIN/metrics/node-exporter)
  ansible.builtin.set_fact:
    matrix_nginx_proxy_proxy_matrix_metrics_additional_system_location_configuration_blocks: |
      {{
        matrix_nginx_proxy_proxy_matrix_metrics_additional_system_location_configuration_blocks | default([])
        +
        [matrix_prometheus_node_exporter_nginx_metrics_configuration_block]
      }}