Prometheus rules for basic machine health of my NAS

host_health.yaml

groups:
  - name: host.health
    rules:
      - alert: SmartFailure
        expr: smartmon_device_smart_healthy != 1
        labels:
          severity: "critical"
        annotations:
          summary: "Disk {{ $labels.disk }} on {{ $labels.instance }} has a SMART failure."
      - alert: DiskFullPercentage
        expr: (node_filesystem_avail_bytes{type!="tmpfs"} / node_filesystem_size_bytes{type!="tmpfs"}) and (node_filesystem_size_bytes{type!="tmpfs"} < 256*1024*1024*1024) < 0.1
        labels:
          severity: "critical"
        annotations:
          summary: "Disk {{ $labels.device }} ({{ $labels.fstype }} on {{ $labels.instance }} has {{ humanizePercentage $value }} space available."
      - alert: LargeDiskFullSpace
        expr: (node_filesystem_avail_bytes{mountpoint!~"(\\/run|\\/boot\\/efi).*"} < 50*1024*1024*1024) and (node_filesystem_size_bytes{type!="tmpfs"} > 256*1024*1024*1024)
        labels:
          severity: "critical"
        annotations:
          summary: "Disk {{ $labels.device }} ({{ $labels.fstype }} on {{ $labels.instance }} has {{ humanize1024 $value }} of space available."
      - alert: DiskFullSpace
        expr: (node_filesystem_avail_bytes{mountpoint!~"(\\/run|\\/boot\\/efi).*"} < 1024*1024*1024)
        labels:
          severity: "critical"
        annotations:
          summary: "Disk {{ $labels.device }} ({{ $labels.fstype }} on {{ $labels.instance }} has {{ humanize1024 $value }} of space available."