Collect hardware and OS metrics with node exporter

- Main examples:
  - https://github.com/oijkn/Docker-Raspberry-PI-Monitoring/blob/main/docker-compose.yml#L46-L65
  - https://github.com/prometheus/node_exporter/tree/f35a592dd65d6b3488426a789b328c8ca5b2bc22?tab=readme-ov-file#docker
  - https://theawesomegarage.com/blog/monitor-your-raspberry-pi-with-prometheus-and-grafana
- I attempted to use `network_mode: host` as in the node_exporter README example, but then I needed to add `extra_hosts: ["host.docker.internal:host-gateway"]` to the prometheus service and `- targets: ['host.docker.internal:9100']` to prometheus.yml as recommended by https://stackoverflow.com/a/66689508 but the connection was always refused
  - Additionally, I think this would have exposed the :9100/metrics endpoint publicly
  - The downside of not using `network_mode: host` is that the network metrics only include network traffic that goes through the docker container, and not the node itself. This should be fine though, since theoretically all network traffic that isn't admin-related (i.e. me) should go through the docker containers
- I needed to remove rslave from `/:/host:ro,rslave` or else `dc up` failed on mac.
  - https://docs.docker.com/engine/storage/bind-mounts/#configure-bind-propagation
  - prometheus/node_exporter#2002
  - prometheus-community/helm-charts#467
  - prometheus/node_exporter#610 (comment)

Author: High5Apps

compose.yaml

@@ -81,6 +81,20 @@ services:
     image: prometheuscommunity/postgres-exporter:v0.15.0
     ports:
       - "127.0.0.1:9187:9187"
+  monitor-node:
+    image: prom/node-exporter:v1.8.2
+    command:
+      - --path.procfs=/host/proc
+      - --path.sysfs=/host/sys
+      - --path.rootfs=/host
+    ports:
+      - "127.0.0.1:9100:9100"
+    restart: unless-stopped
+    volumes:
+      - /proc:/host/proc:ro
+      - /sys:/host/sys:ro
+      - /:/rootfs:ro
+      - /:/host:ro
   site:
     build:
       context: site

monitor/prometheus.yml

@@ -11,3 +11,6 @@ scrape_configs:
   - job_name: 'cadvisor'
     static_configs:
       - targets: ['monitor-containers:8080']
+  - job_name: 'node-exporter'
+    static_configs:
+      - targets: ['monitor-node:9100']