feat(BA-5989): add node-exporter to halfstack observability profile (#11541)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Yaminyam

changes/11541.feature.md

@@ -0,0 +1,3 @@
+Add `node-exporter` to the halfstack `observability` profile so Prometheus
+automatically scrapes host-level metrics (CPU, memory, disk, network) in local
+dev environments.

configs/prometheus/prometheus-ha.yaml

@@ -40,3 +40,7 @@ scrape_configs:
     static_configs:
       - targets:
           - backendai-half-db-exporter:9187
+  - job_name: 'node-exporter'
+    static_configs:
+      - targets:
+          - backendai-half-node-exporter:9100

configs/prometheus/prometheus.yaml

@@ -38,3 +38,7 @@ scrape_configs:
     static_configs:
       - targets:
           - backendai-half-db-exporter:9187
+  - job_name: 'node-exporter'
+    static_configs:
+      - targets:
+          - backendai-half-node-exporter:9100

docker-compose.halfstack-ha.yml

@@ -76,6 +76,25 @@ services:
     depends_on:
       - backendai-half-redis-node03
 
+  backendai-half-node-exporter:
+    image: prom/node-exporter:v1.9.1
+    profiles: ["observability"]
+    restart: unless-stopped
+    networks:
+      - half
+    pid: host
+    command:
+      - '--path.procfs=/host/proc'
+      - '--path.sysfs=/host/sys'
+      - '--path.rootfs=/host/root'
+      - '--collector.filesystem.mount-points-exclude=^/(sys|proc|dev|host|etc)($$|/)'
+    volumes:
+      - /proc:/host/proc:ro
+      - /sys:/host/sys:ro
+      - /:/host/root:ro,rslave
+    ports:
+      - "9100:9100"
+
   # Initial master is redis-node01.
   backendai-half-redis-node01:
     image: redis:7.2.11-alpine

docker-compose.halfstack-main.yml

@@ -78,6 +78,25 @@ services:
     ports:
       - "9121:9121"
 
+  backendai-half-node-exporter:
+    image: prom/node-exporter:v1.9.1
+    profiles: ["observability"]
+    restart: unless-stopped
+    networks:
+      - half
+    pid: host
+    command:
+      - '--path.procfs=/host/proc'
+      - '--path.sysfs=/host/sys'
+      - '--path.rootfs=/host/root'
+      - '--collector.filesystem.mount-points-exclude=^/(sys|proc|dev|host|etc)($$|/)'
+    volumes:
+      - /proc:/host/proc:ro
+      - /sys:/host/sys:ro
+      - /:/host/root:ro,rslave
+    ports:
+      - "9100:9100"
+
   backendai-half-etcd:
     image: quay.io/coreos/etcd:v3.5.14
     restart: unless-stopped