Skip to main content

​
Description

The check_port probe performs a TCP connect to verify whether a port on a host is reachable. Supports both expecting the port to be open (default) and expecting it to be closed. This is an active check — emits both metrics and a check result with latency.

​
Config fields

FieldTypeRequiredDefaultDescription
typestringYes—Must be "check_port"
hoststringYes—Host or IP to check
portintYes—TCP port (1–65535)
expectOpenboolNotruetrue: expect port open → up on successful connect. false: expect port closed → up on connect failure

​
Metrics

MetricTypeUnitDescription
vms.check_port.statusstatus—up or down
vms.check_port.latency_msgaugemsTCP connect time

​
Example config

{
  "type": "check_port",
  "host": "10.0.0.10",
  "port": 443,
  "expectOpen": true
}
Check that a port is closed: 
{
  "type": "check_port",
  "host": "10.0.0.10",
  "port": 3389,
  "expectOpen": false
}

​
Notes

  • When the result doesn’t match the expectation, severity is critical.
  • A connect failure due to network is a normal result (status=down), not an agent error.