Vero Monitor Service

Description

The ping probe checks host reachability using ICMP echo (unprivileged datagram socket). If ICMP is unavailable (missing CAP_NET_RAW or net.ipv4.ping_group_range doesn’t cover the agent’s user), it automatically falls back to TCP connect.

Config fields

Field	Type	Required	Default	Description
`type`	`string`	Yes	—	Must be `"ping"`
`host`	`string`	Yes	—	Host or IP to ping
`count`	`int`	No	`3`	Number of pings (1–10). Values > 10 are clamped
`method`	`string`	No	`""` (auto)	`"icmp"`: ICMP only. `"tcp_fallback"`: TCP only. Empty: try ICMP first, fall back to TCP
`fallbackPort`	`int`	No	`443`	TCP port for fallback (1–65535)

Metrics

Metric	Type	Unit	Labels	Description
`vms.ping.status`	status	—	`method`	`up` or `down`
`vms.ping.latency_ms`	gauge	ms	`method`	Average latency
`vms.agent.permission_missing`	gauge	—	`capability=CAP_NET_RAW`	Emitted when ICMP is blocked and probe uses TCP fallback

Example config

{
  "type": "ping",
  "host": "10.0.0.10",
  "count": 3,
  "fallbackPort": 443
}

Notes

ICMP unavailability is detected once at construction, not re-probed every run.
When ICMP is blocked, the probe emits vms.agent.permission_missing{capability=CAP_NET_RAW} every run so the gap is visible on dashboards.
To enable native ICMP on Linux: grant CAP_NET_RAW to the binary or expand net.ipv4.ping_group_range.