Add logout command to CLI (yorkie-team#571)

cmd/yorkie/config/config.go

@@ -122,3 +122,18 @@ func Save(config *Config) error {
 
 	return nil
 }
+
+// Delete deletes the configuration file.
+func Delete() error {
+	configPathValue, err := configPath()
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "get config path: %w", err)
+		os.Exit(1)
+	}
+
+	if err := os.Remove(filepath.Clean(configPathValue)); err != nil {
+		return fmt.Errorf("remove config file: %w", err)
+	}
+
+	return nil
+}

cmd/yorkie/logout.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/spf13/cobra"
+
+	"github.com/yorkie-team/yorkie/cmd/yorkie/config"
+)
+
+var (
+	flagForce bool
+)
+
+func newLogoutCmd() *cobra.Command {
+	return &cobra.Command{
+		Use:   "logout",
+		Short: "Log out from the Yorkie server",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			conf, err := config.Load()
+			if err != nil {
+				return err
+			}
+			if flagForce {
+				return config.Delete()
+			}
+			if config.RPCAddr == "" {
+				return errors.New("you must specify the server address to log out")
+			}
+			if _, ok := conf.Auths[config.RPCAddr]; !ok {
+				return fmt.Errorf("you are not logged in to %s", config.RPCAddr)
+			}
+			if len(conf.Auths) <= 1 {
+				return config.Delete()
+			}
+			delete(conf.Auths, config.RPCAddr)
+			return config.Save(conf)
+		},
+	}
+}
+
+func init() {
+	cmd := newLogoutCmd()
+	cmd.Flags().BoolVar(
+		&flagForce,
+		"force",
+		false,
+		"force log out from all servers",
+	)
+	rootCmd.AddCommand(cmd)
+}