Go CLI with Cobra

package main

import (
	"fmt"
	"os"

	"github.com/spf13/cobra"
)

var rootCmd = &cobra.Command{
	Use:   "mytool",
	Short: "A helpful CLI tool",
	Long:  `mytool is a CLI application built with Cobra.`,
}

var serveCmd = &cobra.Command{
	Use:   "serve",
	Short: "Start the HTTP server",
	RunE: func(cmd *cobra.Command, args []string) error {
		port, _ := cmd.Flags().GetInt("port")
		fmt.Printf("Starting server on :%d\n", port)
		// server logic here
		return nil
	},
}

var versionCmd = &cobra.Command{
	Use:   "version",
	Short: "Print the version",
	Run: func(cmd *cobra.Command, args []string) {
		fmt.Println("mytool v1.0.0")
	},
}

func init() {
	serveCmd.Flags().IntP("port", "p", 8080, "Port to listen on")
	rootCmd.AddCommand(serveCmd, versionCmd)
}

func main() {
	if err := rootCmd.Execute(); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}