2-2. Namespace

Let's make a low-leveled container runtime!

package main

import (
	"log"
	"os"
	"os/exec"
	"runtime"

	"github.com/k1LoW/errors"
	"golang.org/x/sys/unix"
)

func main() {
	switch os.Args[1] {
	case "run":
		if err := run(os.Args[2:]); err != nil {
			log.Fatalln(errors.StackTraces(err))
		}

	default:
		log.Fatalf("unknown command: %s", os.Args[1])
	}
}

func run(command []string) error {
	runtime.LockOSThread() 
	defer runtime.UnlockOSThread() 

	if err := unix.Unshare(unix.CLONE_NEWUTS); err != nil { 
		return errors.WithStack(err) 
	} 

	path, err := exec.LookPath(command[0])
	if err != nil {
		return errors.WithStack(err)
	}

	if err := unix.Exec(path, command, os.Environ()); err != nil {
		return errors.WithStack(err)
	}

	return nil
}