Contrail provides Analytics API to query status of contrail objects, this KB provides Analytics query as required to query the status of VMI.
This case be helpful to monitor the status of Service Instance, especially when port tuples are associated with health check objects.
Here is the analytics url for the same
http://<controller-ip>8081/analytics/uves/virtual-machine-interface/default-domain:admin:uuid?flat
The response will have details about the status of the VMI's as below
For Active VMI
"UveVMInterfaceAgent": {
"__T": xxx,
"active": true,
"admin_state": true,
For Standby VMI
"__T": xxxx,
"active": false,