Create new network namespace without any process member

newNetworkNamespace.go

func MountNewNetworkNamespace(nsTarget string) (filesystem.Unmounter, error) {
	_, err := os.OpenFile(nsTarget, syscall.O_RDONLY|syscall.O_CREAT|syscall.O_EXCL, 0644)
	if err != nil {
		return nil, errors.Wrap(err, "unable to create target file")
	}

	// store current network namespace
	file, err = os.OpenFile("/proc/self/ns/net", os.O_RDONLY, 0)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	if err := syscall.Unshare(syscall.CLONE_NEWNET); err != nil {
		return nil, errors.Wrap(err, "unshare syscall failed")
	}
	mountPoint := filesystem.MountOption{
		Source: "/proc/self/ns/net",
		Target: nsTarget,
		Type:   "bind",
		Flag:   syscall.MS_BIND,
	}
	unmount, err := filesystem.Mount(mountPoint)
	if err != nil {
		return unmount, err
	}

	// reset previous network namespace
	if err := unix.Setns(int(file.Fd()), syscall.CLONE_NEWNET); err != nil {
		return unmount, errors.Wrap(err, "setns syscall failed: ")
	}

	return unmount, nil
}