Join vnet as a part of NC publish (#451)

Join vnet before publishing NC. This is required as nmagent may be
restarted which causes the NC publishing to fail.

cns/restserver/restserver.go

@@ -113,6 +113,7 @@ func NewHTTPRestService(config *common.ServiceConfig) (HTTPService, error) {
 
 	serviceState := &httpRestServiceState{}
 	serviceState.Networks = make(map[string]*networkInfo)
+	serviceState.joinedNetworks = make(map[string]struct{})
 
 	return &HTTPRestService{
 		Service:          service,
@@ -124,7 +125,6 @@ func NewHTTPRestService(config *common.ServiceConfig) (HTTPService, error) {
 		routingTable:     routingTable,
 		state:            serviceState,
 	}, nil
-
 }
 
 // Start starts the CNS listener.
@@ -1757,10 +1757,6 @@ func (service *HTTPRestService) isNetworkJoined(networkID string) bool {
 	namedLock.LockAcquire(stateJoinedNetworks)
 	defer namedLock.LockRelease(stateJoinedNetworks)
 
-	if service.state.joinedNetworks == nil {
-		service.state.joinedNetworks = make(map[string]struct{})
-	}
-
 	_, exists := service.state.joinedNetworks[networkID]
 
 	return exists
@@ -1819,9 +1815,7 @@ func (service *HTTPRestService) publishNetworkContainer(w http.ResponseWriter, r
 
 	switch r.Method {
 	case "POST":
-		// Join Network if not joined already
-		isNetworkJoined = service.isNetworkJoined(req.NetworkID)
-		if !isNetworkJoined {
+		// Join the network
 		publishResponse, publishError, err = service.joinNetwork(req.NetworkID, req.JoinNetworkURL)
 		if err == nil {
 			isNetworkJoined = true
@@ -1829,7 +1823,6 @@ func (service *HTTPRestService) publishNetworkContainer(w http.ResponseWriter, r
 			returnMessage = err.Error()
 			returnCode = NetworkJoinFailed
 		}
-		}
 
 		if isNetworkJoined {
 			// Publish Network Container