Migration to sub command

application/config.go

@@ -91,6 +91,11 @@ func (c *Configuration) Set(path string) error {
 	return yaml.NewDecoder(bytes.NewReader(data)).Decode(c)
 }
 
+// Type returns value type of itself
+func (c *Configuration) Type() string {
+	return "string"
+}
+
 // Addr returns a string of server port
 func (c *Configuration) Addr() string {
 	return fmt.Sprintf(":%d", c.Server.Port)

application/config_test.go

@@ -109,6 +109,16 @@ func TestConfiguration_Set(t *testing.T) {
 	})
 }
 
+func TestConfiguration_Type(t *testing.T) {
+	// when
+	actual := application.Config.Type()
+
+	// expect
+	if actual != "string" {
+		t.Errorf("type should equal string, but got %+v", actual)
+	}
+}
+
 func TestConfiguration_Addr(t *testing.T) {
 	// given
 	application.Config.Server.Port = 8823

go.mod

@@ -45,6 +45,8 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/sergi/go-diff v1.0.0 // indirect
 	github.com/sirupsen/logrus v1.0.6 // indirect
+	github.com/spf13/cobra v0.0.3
+	github.com/spf13/pflag v1.0.3 // indirect
 	github.com/src-d/gcfg v1.3.0 // indirect
 	github.com/stretchr/testify v1.2.2 // indirect
 	github.com/syndtr/goleveldb v0.0.0-20180815032940-ae2bd5eed72d

main.go

@@ -1,21 +1,34 @@
 package main
 
 import (
-	"flag"
 	"github.com/duck8823/duci/application"
 	"github.com/duck8823/duci/application/semaphore"
 	"github.com/duck8823/duci/infrastructure/logger"
 	"github.com/duck8823/duci/presentation/router"
 	"github.com/google/uuid"
+	"github.com/spf13/cobra"
 	"net/http"
 	"os"
 )
 
 func main() {
-	mainID := uuid.New()
+	serverCmd := &cobra.Command{
+		Use: "server",
+		Run: serverCmd,
+	}
+	serverCmd.PersistentFlags().VarP(application.Config, "config", "c", "configuration file path")
+
+	rootCmd := &cobra.Command{Use: "duci"}
+	rootCmd.AddCommand(serverCmd)
+
+	if err := rootCmd.Execute(); err != nil {
+		logger.Errorf(uuid.New(), "Failed to execute command.\n%+v", err)
+		os.Exit(1)
+	}
+}
 
-	flag.Var(application.Config, "c", "configuration file path")
-	flag.Parse()
+func serverCmd(cmd *cobra.Command, _ []string) {
+	mainID := uuid.New()
 
 	if err := semaphore.Make(); err != nil {
 		logger.Errorf(mainID, "Failed to initialize a semaphore.\n%+v", err)