Add function logs support (#53) (#131)

Add function log aggregation and persistence using Fluentd and InfluxDB.

Fluentd and a helper sidecar run as a daemonset.  The poolmgr sets up logging for each function pod, using the helper sidecar. Fluentd forwards logs to InfluxDB, which is run as a deployment and service. The client CLI directly queries InfluxDB for logs.

Fluentd supports many outputs besides InfluxDB, so we aren't very tied to InfluxDB.

The setup is somewhat manual, which we should be able to improve by integrating this into the helm chart.

Diagram of component interactions: https://cloud.githubusercontent.com/assets/202578/23100399/b0e3ea00-f6ba-11e6-8f2f-6588cfef2e84.png

fission-bundle/main.go

@@ -7,6 +7,7 @@ import (
 	"github.com/docopt/docopt-go"
 	"github.com/fission/fission/controller"
 	"github.com/fission/fission/kubewatcher"
+	"github.com/fission/fission/logger"
 	"github.com/fission/fission/poolmgr"
 	"github.com/fission/fission/router"
 )
@@ -47,6 +48,11 @@ func runKubeWatcher(controllerUrl, routerUrl string) {
 	}
 }
 
+func runLogger() {
+	logger.Start()
+	log.Fatalf("Error: Logger exited.")
+}
+
 func getPort(portArg interface{}) int {
 	portArgStr := portArg.(string)
 	port, err := strconv.Atoi(portArgStr)
@@ -80,6 +86,7 @@ Usage:
   fission-bundle --routerPort=<port> [--controllerUrl=<url> --poolmgrUrl=<url>]
   fission-bundle --poolmgrPort=<port> [--controllerUrl=<url> --namespace=<namespace>]
   fission-bundle --kubewatcher [--controllerUrl=<url> --routerUrl=<url>]
+  fission-bundle --logger
 Options:
   --controllerPort=<port>  Port that the controller should listen on.
   --routerPort=<port>      Port that the router should listen on.
@@ -91,6 +98,7 @@ Options:
   --filepath=<filepath>    Directory to store functions in.
   --namespace=<namespace>  Kubernetes namespace in which to run function containers. Defaults to 'fission-function'.
   --kubewatcher            Start Kubernetes events watcher.
+  --logger                 Start logger.
 `
 	arguments, err := docopt.Parse(usage, nil, true, "fission-bundle", false)
 	if err != nil {
@@ -123,5 +131,9 @@ Options:
 		runKubeWatcher(controllerUrl, routerUrl)
 	}
 
+	if arguments["--logger"] == true {
+		runLogger()
+	}
+
 	select {}
 }