updated code structure

backend/cmd/api.go

@@ -10,12 +10,12 @@ func init() {
 }
 
 var apiCmd = &cobra.Command{
-	Use:   "api",
-	Short: "Start API server",
-	Long:  `Start API server of Crawlab which serves data to frontend`,
+	Use:     "api",
+	Aliases: []string{"A"},
+	Short:   "Start API server",
+	Long:    `Start API server of Crawlab which serves data to frontend`,
 	Run: func(cmd *cobra.Command, args []string) {
 		api := apps.NewApi()
-		api.Init()
-		api.Run()
+		apps.Start(api)
 	},
 }

backend/cmd/handler.go

@@ -10,13 +10,13 @@ func init() {
 }
 
 var handlerCmd = &cobra.Command{
-	Use:   "handler",
-	Short: "Start task handler",
-	Long: `Start task handler service (worker) of Crawlab 
-which runs tasks assigned by master node`,
+	Use:     "handler",
+	Aliases: []string{"H"},
+	Short:   "Start handler",
+	Long: `Start a handler instance of Crawlab 
+which runs tasks with given parameters`,
 	Run: func(cmd *cobra.Command, args []string) {
 		handler := apps.NewHandler()
-		handler.Init()
-		handler.Run()
+		apps.Start(handler)
 	},
 }

backend/cmd/master.go

@@ -0,0 +1,22 @@
+package cmd
+
+import (
+	"crawlab/apps"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(masterCmd)
+}
+
+var masterCmd = &cobra.Command{
+	Use:     "master",
+	Aliases: []string{"M"},
+	Short:   "Start master",
+	Long: `Start a master instance of Crawlab 
+which runs api and assign tasks to worker nodes`,
+	Run: func(cmd *cobra.Command, args []string) {
+		master := apps.NewMaster()
+		apps.Start(master)
+	},
+}

backend/cmd/worker.go

@@ -0,0 +1,23 @@
+package cmd
+
+import (
+	"crawlab/apps"
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	rootCmd.AddCommand(workerCmd)
+}
+
+var workerCmd = &cobra.Command{
+	Use:     "worker",
+	Aliases: []string{"W"},
+	Short:   "Start worker",
+	Long: `Start a worker instance of Crawlab 
+serving in the worker node and executes tasks
+assigned by the master node`,
+	Run: func(cmd *cobra.Command, args []string) {
+		worker := apps.NewWorker()
+		apps.Start(worker)
+	},
+}