Netdata: add alerts for cpu, ram, disks

files/netdata/health.d/system_resources.conf

@@ -0,0 +1,67 @@
+# Resource alerts for a low-spec home server.
+# Overrides stock alerts where thresholds differ; baseline RAM use is ~80%, so stock 80/90% would fire constantly.
+
+# RAM: warn at >92%, crit at >95% — by then less than ~200 MB free.
+ alarm: ram_in_use
+    on: system.ram
+ class: Utilization
+  type: System
+component: Memory
+  calc: $used * 100 / ($used + $cached + $free + $buffers)
+ units: %
+ every: 10s
+  warn: $this > 92
+  crit: $this > 95
+ delay: down 5m multiplier 1.5 max 1h
+summary: System memory utilization
+   info: System memory utilization (used / total, excluding reclaimable cache)
+    to: sysadmin
+
+# CPU: replace stock 10min_cpu_usage with two windowed alerts.
+ alarm: 10min_cpu_usage
+    on: system.cpu
+enabled: no
+
+ alarm: cpu_warn_30m
+    on: system.cpu
+ class: Utilization
+  type: System
+component: CPU
+lookup: average -30m unaligned of user,system,softirq,irq,guest,guest_nice,nice
+ units: %
+ every: 1m
+  warn: $this > 80
+ delay: down 30m multiplier 1.5 max 2h
+summary: Sustained CPU load (30m avg)
+   info: Average CPU utilization over the last 30 minutes
+    to: sysadmin
+
+ alarm: cpu_crit_15m
+    on: system.cpu
+ class: Utilization
+  type: System
+component: CPU
+lookup: average -15m unaligned of user,system,softirq,irq,guest,guest_nice,nice
+ units: %
+ every: 1m
+  crit: $this > 95
+ delay: down 30m multiplier 1.5 max 2h
+summary: High CPU load (15m avg)
+   info: Average CPU utilization over the last 15 minutes
+    to: sysadmin
+
+# Disk: warn at >75%, crit at >90% on every mounted filesystem.
+ template: disk_space_usage
+       on: disk.space
+    class: Utilization
+     type: System
+component: Disk
+     calc: $used * 100 / ($avail + $used)
+    units: %
+    every: 1m
+     warn: $this > 75
+     crit: $this > 90
+    delay: down 15m multiplier 1.5 max 1h
+  summary: Disk space utilization
+     info: Disk space utilization on ${label:mount_point}
+       to: sysadmin