From 5c34cb69808a15b85df30f14a8a902fa360a693c Mon Sep 17 00:00:00 2001
From: nbn01 <nandan_bn@intuit.com>
Date: Mon, 7 Nov 2022 21:39:56 +0530
Subject: [PATCH] fix: Handle VS hosts nil

---
 admiral/pkg/clusters/handler.go | 66 +++++++++++++++++----------------
 1 file changed, 34 insertions(+), 32 deletions(-)

diff --git a/admiral/pkg/clusters/handler.go b/admiral/pkg/clusters/handler.go
index a2bf4e70..6bafd72c 100644
--- a/admiral/pkg/clusters/handler.go
+++ b/admiral/pkg/clusters/handler.go
@@ -418,49 +418,51 @@ func handleVirtualServiceEvent(
 		}
 	}
 
-	dependentClusters := r.AdmiralCache.CnameDependentClusterCache.Get(virtualService.Hosts[0]).Copy()
-	if len(dependentClusters) > 0 {
-		for _, dependentCluster := range dependentClusters {
-			rc := r.GetRemoteController(dependentCluster)
-			if clusterId != dependentCluster {
-				log.Infof(LogFormat, "Event", "VirtualService", obj.Name, clusterId, "Processing")
-				if event == common.Delete {
-					err := rc.VirtualServiceController.IstioClient.NetworkingV1alpha3().VirtualServices(syncNamespace).Delete(ctx, obj.Name, v12.DeleteOptions{})
-					if err != nil {
-						if k8sErrors.IsNotFound(err) {
-							log.Infof(LogFormat, "Delete", "VirtualService", obj.Name, clusterId, "Either VirtualService was already deleted, or it never existed")
+	if virtualService.Hosts != nil {
+		dependentClusters := r.AdmiralCache.CnameDependentClusterCache.Get(virtualService.Hosts[0]).Copy()
+		if len(dependentClusters) > 0 {
+			for _, dependentCluster := range dependentClusters {
+				rc := r.GetRemoteController(dependentCluster)
+				if clusterId != dependentCluster {
+					log.Infof(LogFormat, "Event", "VirtualService", obj.Name, clusterId, "Processing")
+					if event == common.Delete {
+						err := rc.VirtualServiceController.IstioClient.NetworkingV1alpha3().VirtualServices(syncNamespace).Delete(ctx, obj.Name, v12.DeleteOptions{})
+						if err != nil {
+							if k8sErrors.IsNotFound(err) {
+								log.Infof(LogFormat, "Delete", "VirtualService", obj.Name, clusterId, "Either VirtualService was already deleted, or it never existed")
+							} else {
+								log.Errorf(LogErrFormat, "Delete", "VirtualService", obj.Name, clusterId, err)
+							}
 						} else {
-							log.Errorf(LogErrFormat, "Delete", "VirtualService", obj.Name, clusterId, err)
+							log.Infof(LogFormat, "Delete", "VirtualService", obj.Name, clusterId, "Success")
 						}
 					} else {
-						log.Infof(LogFormat, "Delete", "VirtualService", obj.Name, clusterId, "Success")
-					}
-				} else {
-					exist, _ := rc.VirtualServiceController.IstioClient.NetworkingV1alpha3().VirtualServices(syncNamespace).Get(ctx, obj.Name, v12.GetOptions{})
-					//change destination host for all http routes <service_name>.<ns>. to same as host on the virtual service
-					for _, httpRoute := range virtualService.Http {
-						for _, destination := range httpRoute.Route {
-							//get at index 0, we do not support wildcards or multiple hosts currently
-							if strings.HasSuffix(destination.Destination.Host, common.DotLocalDomainSuffix) {
-								destination.Destination.Host = virtualService.Hosts[0]
+						exist, _ := rc.VirtualServiceController.IstioClient.NetworkingV1alpha3().VirtualServices(syncNamespace).Get(ctx, obj.Name, v12.GetOptions{})
+						//change destination host for all http routes <service_name>.<ns>. to same as host on the virtual service
+						for _, httpRoute := range virtualService.Http {
+							for _, destination := range httpRoute.Route {
+								//get at index 0, we do not support wildcards or multiple hosts currently
+								if strings.HasSuffix(destination.Destination.Host, common.DotLocalDomainSuffix) {
+									destination.Destination.Host = virtualService.Hosts[0]
+								}
 							}
 						}
-					}
-					for _, tlsRoute := range virtualService.Tls {
-						for _, destination := range tlsRoute.Route {
-							//get at index 0, we do not support wildcards or multiple hosts currently
-							if strings.HasSuffix(destination.Destination.Host, common.DotLocalDomainSuffix) {
-								destination.Destination.Host = virtualService.Hosts[0]
+						for _, tlsRoute := range virtualService.Tls {
+							for _, destination := range tlsRoute.Route {
+								//get at index 0, we do not support wildcards or multiple hosts currently
+								if strings.HasSuffix(destination.Destination.Host, common.DotLocalDomainSuffix) {
+									destination.Destination.Host = virtualService.Hosts[0]
+								}
 							}
 						}
+						addUpdateVirtualService(ctx, obj, exist, syncNamespace, rc)
 					}
-					addUpdateVirtualService(ctx, obj, exist, syncNamespace, rc)
 				}
 			}
+			return nil
+		} else {
+			log.Infof(LogFormat, "Event", "VirtualService", obj.Name, clusterId, "No dependent clusters found")
 		}
-		return nil
-	} else {
-		log.Infof(LogFormat, "Event", "VirtualService", obj.Name, clusterId, "No dependent clusters found")
 	}
 
 	// copy the VirtualService `as is` if they are not generated by Admiral (not in CnameDependentClusterCache)