Initial support for getting the leader from Zookeeper.

Some tests included for making sure the JSON blob pulled from Zookeeper
is correct.

Updated client to be able to take Zookeeper json cluster config that is
currently being used in aurora (clusters.json usually located at
/etc/aurora/cluster.json).

Changed error messages to no longer have a period at the end as that was
throwing off printing of the error.

Modified samuel's ZK library slightly to stop verbose logging using a
NoOpLogger from stackoverflow.

examples/client.go

@@ -28,15 +28,33 @@ func main() {
 	cmd := flag.String("cmd", "", "Job request type to send to Aurora Scheduler")
 	executor := flag.String("executor", "thermos", "Executor to use")
 	url := flag.String("url", "", "URL at which the Aurora Scheduler exists as [url]:[port]")
+	clustersConfig := flag.String("clusters", "", "Location of the clusters.json file used by aurora.")
 	updateId := flag.String("updateId", "", "Update ID to operate on")
 	username := flag.String("username", "aurora", "Username to use for authorization")
 	password := flag.String("password", "secret", "Password to use for authorization")
 	flag.Parse()
 
+	// Attempt to load leader from zookeeper
+	if *clustersConfig != "" {
+		clusters, err := realis.LoadClusters(*clustersConfig)
+		if err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+
+		cluster, _ := clusters["devcluster"]
+
+		*url, err = realis.LeaderFromZK(cluster)
+		if err != nil {
+			fmt.Println(err)
+			os.Exit(1)
+		}
+	}
+
 	//Create new configuration with default transport layer
 	config, err := realis.NewDefaultConfig(*url)
 	if err != nil {
-		fmt.Print(err)
+		fmt.Println(err)
 		os.Exit(1)
 	}
 
@@ -51,7 +69,7 @@ func main() {
 	case "thermos":
 		payload, err := ioutil.ReadFile("examples/thermos_payload.json")
 		if err != nil {
-			fmt.Print("Error reading json config file: ", err)
+			fmt.Println("Error reading json config file: ", err)
 			os.Exit(1)
 		}
 
@@ -94,41 +112,41 @@ func main() {
 		fmt.Println("Creating job")
 		response, err := r.CreateJob(job)
 		if err != nil {
-			fmt.Print(err)
+			fmt.Println(err)
 			os.Exit(1)
 		}
 
-		fmt.Print(response.String())
+		fmt.Println(response.String())
 		break
 	case "kill":
 		fmt.Println("Killing job")
 
 		response, err := r.KillJob(job.JobKey())
 		if err != nil {
-			fmt.Print(err)
+			fmt.Println(err)
 			os.Exit(1)
 		}
 
-		fmt.Print(response.String())
+		fmt.Println(response.String())
 		break
 	case "restart":
 		fmt.Println("Restarting job")
 		response, err := r.RestartJob(job.JobKey())
 		if err != nil {
-			fmt.Print(err)
+			fmt.Println(err)
 			os.Exit(1)
 		}
 
-		fmt.Print(response.String())
+		fmt.Println(response.String())
 		break
 	case "flexUp":
 		fmt.Println("Flexing up job")
 		response, err := r.AddInstances(&aurora.InstanceKey{job.JobKey(), 0}, 5)
 		if err != nil {
-			fmt.Print(err)
+			fmt.Println(err)
 			os.Exit(1)
 		}
-		fmt.Print(response.String())
+		fmt.Println(response.String())
 		break
 	case "update":
 		fmt.Println("Updating a job with a new name")
@@ -138,19 +156,19 @@ func main() {
 
 		resposne, err := r.StartJobUpdate(updateJob, "")
 		if err != nil {
-			fmt.Print(err)
+			fmt.Println(err)
 			os.Exit(1)
 		}
-		fmt.Print(resposne.String())
+		fmt.Println(resposne.String())
 		break
 	case "abortUpdate":
 		fmt.Println("Abort update")
 		response, err := r.AbortJobUpdate(job.JobKey(), *updateId, "")
 		if err != nil {
-			fmt.Print(err)
+			fmt.Println(err)
 			os.Exit(1)
 		}
-		fmt.Print(response.String())
+		fmt.Println(response.String())
 		break
 	default:
 		fmt.Println("Only create, kill, restart, flexUp, update, and abortUpdate are supported now")

examples/clusters.json

@@ -0,0 +1,8 @@
+[{
+  "name": "devcluster",
+  "zk": "192.168.33.7",
+  "scheduler_zk_path": "/aurora/scheduler",
+  "auth_mechanism": "UNAUTHENTICATED",
+  "slave_run_directory": "latest",
+  "slave_root": "/var/lib/mesos"
+}]