Add message queue trigger support (#218)

Adds support for message queue triggers based on the NATS-Streaming message queue.

This lets the user map a queue topic to a function, and optionally send the function's response into another queue topic.

The message queue trigger manager is designed to be message queue independent, so we should be able add support for more queues by adding implementations for the relatively simple mqtrigger.MessageQueue interface.

fission-bundle/main.go

@@ -8,6 +8,7 @@ import (
 	"github.com/fission/fission/controller"
 	"github.com/fission/fission/kubewatcher"
 	"github.com/fission/fission/logger"
+	"github.com/fission/fission/mqtrigger"
 	"github.com/fission/fission/poolmgr"
 	"github.com/fission/fission/router"
 	"github.com/fission/fission/timer"
@@ -61,6 +62,13 @@ func runTimer(controllerUrl, routerUrl string) {
 	}
 }
 
+func runMessageQueueMgr(controllerUrl, routerUrl string) {
+	err := messagequeue.Start(controllerUrl, routerUrl)
+	if err != nil {
+		log.Fatalf("Error starting timer: %v", err)
+	}
+}
+
 func getPort(portArg interface{}) int {
 	portArgStr := portArg.(string)
 	port, err := strconv.Atoi(portArgStr)
@@ -96,6 +104,7 @@ Usage:
   fission-bundle --kubewatcher [--controllerUrl=<url> --routerUrl=<url>]
   fission-bundle --logger
   fission-bundle --timer [--controllerUrl=<url> --routerUrl=<url>]
+  fission-bundle --mqt   [--controllerUrl=<url> --routerUrl=<url>]
 Options:
   --controllerPort=<port>  Port that the controller should listen on.
   --routerPort=<port>      Port that the router should listen on.
@@ -109,6 +118,7 @@ Options:
   --kubewatcher            Start Kubernetes events watcher.
   --logger                 Start logger.
   --timer 		           Start Timer.
+  --mqt 		           Start message queue trigger.
 `
 	arguments, err := docopt.Parse(usage, nil, true, "fission-bundle", false)
 	if err != nil {
@@ -149,5 +159,9 @@ Options:
 		runTimer(controllerUrl, routerUrl)
 	}
 
+	if arguments["--mqt"] == true {
+		runMessageQueueMgr(controllerUrl, routerUrl)
+	}
+
 	select {}
 }