Put topic in the config file

src/github.com/matrix-org/dendrite/clientapi/clientapi.go

@@ -52,6 +52,7 @@ func main() {
 		KeyID:                "ed25519:something",
 		PrivateKey:           privKey,
 		KafkaProducerURIs:    []string{"localhost:9092"},
+		ClientAPIOutputTopic: "clientapiOutput",
 	}
 
 	log.Info("Starting clientapi")

src/github.com/matrix-org/dendrite/clientapi/config/config.go

@@ -13,4 +13,6 @@ type ClientAPI struct {
 	KeyID string
 	// A list of URIs to send events to. These kafka logs should be consumed by a Room Server.
 	KafkaProducerURIs []string
+	// The topic for events which are written to the logs.
+	ClientAPIOutputTopic string
 }

src/github.com/matrix-org/dendrite/clientapi/writers/createroom.go

@@ -181,7 +181,7 @@ func createRoom(req *http.Request, cfg config.ClientAPI, roomID string, producer
 	}
 
 	// send events to the room server
-	msgs, err := eventsToMessages(builtEvents)
+	msgs, err := eventsToMessages(builtEvents, cfg.ClientAPIOutputTopic)
 	if err != nil {
 		return util.ErrorResponse(err)
 	}
@@ -252,7 +252,7 @@ func authEventsFromStateNeeded(eventsNeeded gomatrixserverlib.StateNeeded,
 	return
 }
 
-func eventsToMessages(events []*gomatrixserverlib.Event) ([]*sarama.ProducerMessage, error) {
+func eventsToMessages(events []*gomatrixserverlib.Event, topic string) ([]*sarama.ProducerMessage, error) {
 	msgs := make([]*sarama.ProducerMessage, len(events))
 	for i, e := range events {
 		var m sarama.ProducerMessage
@@ -273,7 +273,7 @@ func eventsToMessages(events []*gomatrixserverlib.Event) ([]*sarama.ProducerMess
 		if err != nil {
 			return nil, err
 		}
-		m.Topic = "clientapiOutput" // TODO: Make this customisable like roomserver is?
+		m.Topic = topic
 		m.Key = sarama.StringEncoder(e.EventID())
 		m.Value = sarama.ByteEncoder(value)
 		msgs[i] = &m