https://prometheus.io/docs/guides/query-log/

Debian

CPU Usage (%)

100 - (avg by (instance) (irate(node_cpu_seconds_total{job="Deb-1",mode="idle"}[1m])) * 100)

RAM Usage (%)

100 * (1 - (node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes))

Disk Usage (%)

100 * (1 - (node_filesystem_free_bytes{mountpoint="/"}) / node_filesystem_size_bytes{mountpoint="/"})

Windows

CPU Usage (%)

100 - (avg(irate(windows_cpu_time_total{mode="idle"}[5m])) * 100)

RAM Usage (%)

100.0 - (100 * (windows_os_physical_memory_free_bytes / windows_cs_physical_memory_bytes))

Disk C:\ Usage (%)

100.0 - (100 * (windows_logical_disk_free_bytes{volume="C:"} / windows_logical_disk_size_bytes{volume="C:"}))