> ## Documentation Index
> Fetch the complete documentation index at: https://docs.vms.verolabs.co/llms.txt
> Use this file to discover all available pages before exploring further.

# Probe: host_resource

> Collect CPU, memory, disk, disk IO, and network metrics from the host

## Description

The `host_resource` probe collects host-level resource metrics: CPU usage, memory usage, disk utilization, disk I/O, and network traffic. This is a pure collector — it emits gauge/counter metrics only, no check result.

Requires the `HostAdapter` platform adapter — supported on Linux and Windows only. If the adapter is unavailable on the current platform, the probe is skipped at construction.

## Config fields

| Field               | Type       | Required | Default        | Description                                                                      |
| ------------------- | ---------- | -------- | -------------- | -------------------------------------------------------------------------------- |
| `type`              | `string`   | Yes      | —              | Must be `"host_resource"`                                                        |
| `collectCpu`        | `bool`     | No       | `false`        | Enable CPU usage percent collection                                              |
| `collectMemory`     | `bool`     | No       | `false`        | Enable memory usage percent collection                                           |
| `collectDisk`       | `bool`     | No       | `false`        | Enable disk usage percent collection per mount point                             |
| `collectDiskIo`     | `bool`     | No       | `false`        | Enable disk read/write bytes collection per device                               |
| `collectNetwork`    | `bool`     | No       | `false`        | Enable network rx/tx bytes, errors, drops collection per interface               |
| `diskMounts`        | `string[]` | No       | all mounts     | Mount points to monitor. Empty = all                                             |
| `diskDevices`       | `string[]` | No       | all devices    | Disk devices for I/O monitoring. Empty = all real block devices (skips loop/ram) |
| `networkInterfaces` | `string[]` | No       | all interfaces | Network interfaces to monitor. Empty = all                                       |

<Warning>
  At least one `collect*` flag must be enabled, otherwise the probe fails at construction.
</Warning>

## Metrics

| Metric                          | Type    | Unit    | Labels   | Condition                       |
| ------------------------------- | ------- | ------- | -------- | ------------------------------- |
| `vms.host.cpu.usage_percent`    | gauge   | percent | —        | `collectCpu = true`             |
| `vms.host.memory.usage_percent` | gauge   | percent | —        | `collectMemory = true`          |
| `vms.host.disk.usage_percent`   | gauge   | percent | `mount`  | `collectDisk = true`            |
| `vms.host.disk.read_bytes`      | counter | bytes   | `device` | `collectDiskIo = true`          |
| `vms.host.disk.write_bytes`     | counter | bytes   | `device` | `collectDiskIo = true`          |
| `vms.host.network.rx_bytes`     | counter | bytes   | `iface`  | `collectNetwork = true`         |
| `vms.host.network.tx_bytes`     | counter | bytes   | `iface`  | `collectNetwork = true`         |
| `vms.host.network.rx_errors`    | counter | —       | `iface`  | `collectNetwork = true`         |
| `vms.host.network.rx_drops`     | counter | —       | `iface`  | `collectNetwork = true`         |
| `vms.host.network.tx_errors`    | counter | —       | `iface`  | `collectNetwork = true`         |
| `vms.host.network.tx_drops`     | counter | —       | `iface`  | `collectNetwork = true`         |
| `vms.host.uptime_seconds`       | gauge   | seconds | —        | Always collected when supported |

## Example config

```json theme={null}
{
  "type": "host_resource",
  "collectCpu": true,
  "collectMemory": true,
  "collectDisk": true,
  "collectDiskIo": true,
  "collectNetwork": true,
  "diskMounts": ["/", "/data"],
  "diskDevices": ["sda", "nvme0n1"],
  "networkInterfaces": ["eth0", "bond0"]
}
```

**Minimal config:**

```json theme={null}
{
  "type": "host_resource",
  "collectCpu": true,
  "collectMemory": true
}
```

## Notes

* If one metric family fails (e.g. nonexistent disk mount), the probe continues collecting other families and reports `degraded` status rather than failing entirely.
* Counter metrics (disk I/O, network) are cumulative since boot — downstream computes rates by differencing consecutive samples.