Support customising the NATS Streaming channel.

Signed-off-by: Bruno Miguel Custódio <brunomcustodio@gmail.com>

gateway/vendor/github.com/openfaas/nats-queue-worker/handler/handler.go

@@ -7,18 +7,23 @@ import (
 )
 
 // CreateNATSQueue ready for asynchronous processing
-func CreateNATSQueue(address string, port int, clusterName string, clientConfig NATSConfig) (*NATSQueue, error) {
+func CreateNATSQueue(address string, port int, clusterName, channel string, clientConfig NATSConfig) (*NATSQueue, error) {
 	var err error
 	natsURL := fmt.Sprintf("nats://%s:%d", address, port)
 	log.Printf("Opening connection to %s\n", natsURL)
 
 	clientID := clientConfig.GetClientID()
 
+	// If 'channel' is empty, use the previous default.
+	if channel == "" {
+		channel = "faas-request"
+	}
+
 	queue1 := NATSQueue{
 		ClientID:       clientID,
 		ClusterID:      clusterName,
 		NATSURL:        natsURL,
-		Topic:          "faas-request",
+		Topic:          channel,
 		maxReconnect:   clientConfig.GetMaxReconnect(),
 		reconnectDelay: clientConfig.GetReconnectDelay(),
 		ncMutex:        &sync.RWMutex{},