Prometheus Node Exporter

Basic system stats, to show stuff the synapse metrics
can't show such as resource usage by bridges, etc

Seems to work fine as well.

This too has only been tested on debian amd64 so far

roles/matrix-prometheus/templates/prometheus.yml.j2

@@ -33,3 +33,8 @@ scrape_configs:
     - targets: ['matrix-synapse:{{ matrix_synapse_metrics_port }}']
   {% endif %}
 
+  {% if matrix_prometheus_node_exporter_enabled %}
+  - job_name: node
+    static_configs:
+      - targets: ['matrix-prometheus-node-exporter:9100']
+  {% endif %}