The monitor warns if no instances for a viking service are known.

That is, if the varnish controller has stored no instances in its
own data structures.

pkg/varnish/monitor.go

@@ -47,6 +47,7 @@ const (
 	vclListErr   = "VCLListFailure"
 	discardErr   = "VCLDiscardFailure"
 	updateErr    = "UpdateFailure"
+	noInstances  = "NoInstances"
 	monitorGood  = "MonitorGood"
 )
 
@@ -173,6 +174,12 @@ func (vc *Controller) monitor(monitorIntvl time.Duration) {
 		for svcName, svc := range vc.svcs {
 			vc.log.Infof("Monitoring Varnish instances in %s",
 				svcName)
+			if len(svc.instances) == 0 {
+				vc.errorEvt(svcName, noInstances,
+					"No known instances for Service: %s",
+					svcName)
+				continue
+			}
 
 			good := true
 			for _, inst := range svc.instances {