docker-machine-driver-xenserver/xenserver/xenserver.go

package xenserver

import (
	"archive/tar"
	"bytes"
	"crypto/rand"
	"crypto/tls"
	"errors"
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/docker/machine/libmachine/drivers"
	"github.com/docker/machine/libmachine/log"
	"github.com/docker/machine/libmachine/mcnflag"
	"github.com/docker/machine/libmachine/mcnutils"
	"github.com/docker/machine/libmachine/ssh"
	"github.com/docker/machine/libmachine/state"
	"github.com/nilshell/xmlrpc"
	"golang.org/x/net/context"

	xsclient "github.com/xenserver/go-xenserver-client"
)

const (
	isoFilename         = "boot2docker.iso"
	tarFilename         = "boot2docker.tar"
	B2D_USER            = "docker"
	B2D_PASS            = "tcuser"
)

type Driver struct {
	*drivers.BaseDriver

	Server              string
	Username            string
	Password            string
	Boot2DockerURL      string
	CPU                 uint
	Memory              uint
	DiskSize            uint
	SR                  string
	Network             string
	Host                string
	ISO                 string
	TAR                 string
	UploadTimeout       uint
	WaitTimeout         uint
	CaCertPath          string
	PrivateKeyPath      string
	osTemplateLabelName string

	xenAPIClient *XenAPIClient
}

// GetCreateFlags registers the flags this driver adds to
// "docker hosts create"
func (d *Driver) GetCreateFlags() []mcnflag.Flag {
	return []mcnflag.Flag{
		mcnflag.StringFlag{
			EnvVar: "XENSERVER_SERVER",
			Name:   "xenserver-server",
			Usage:  "XenServer server hostname/IP for docker VM",
		},
		mcnflag.StringFlag{
			EnvVar: "XENSERVER_USERNAME",
			Name:   "xenserver-username",
			Usage:  "XenServer username",
		},
		mcnflag.StringFlag{
			EnvVar: "XENSERVER_PASSWORD",
			Name:   "xenserver-password",
			Usage:  "XenServer password",
		},
		mcnflag.StringFlag{
			EnvVar: "XENSERVER_BOOT2DOCKER_URL",
			Name:   "xenserver-boot2docker-url",
			Usage:  "XenServer URL for boot2docker image",
		},
		mcnflag.IntFlag{
			EnvVar: "XENSERVER_VCPU_COUNT",
			Name:   "xenserver-vcpu-count",
			Usage:  "XenServer vCPU number for docker VM",
			Value:  1,
		},
		mcnflag.IntFlag{
			EnvVar: "XENSERVER_MEMORY_SIZE",
			Name:   "xenserver-memory-size",
			Usage:  "XenServer size of memory for docker VM (in MB)",
			Value:  1024,
		},
		mcnflag.IntFlag{
			EnvVar: "XENSERVER_DISK_SIZE",
			Name:   "xenserver-disk-size",
			Usage:  "XenServer size of disk for docker VM (in MB)",
			Value:  5120,
		},
		mcnflag.StringFlag{
			EnvVar: "XENSERVER_SR_LABEL",
			Name:   "xenserver-sr-label",
			Usage:  "XenServer SR label where the docker VM will be attached",
		},
		mcnflag.StringFlag{
			EnvVar: "XENSERVER_NETWORK_LABEL",
			Name:   "xenserver-network-label",
			Usage:  "XenServer network label where the docker VM will be attached",
		},
		mcnflag.StringFlag{
			EnvVar: "XENSERVER_HOST_LABEL",
			Name:   "xenserver-host-label",
			Usage:  "XenServer host label where the docker VM will be run",
		},
		mcnflag.IntFlag{
			EnvVar: "XENSERVER_UPLOAD_TIMEOUT",
			Name:   "xenserver-upload-timeout",
			Usage:  "XenServer upload VDI timeout(seconds)",
			Value:  5 * 60,
		},
		mcnflag.IntFlag{
			EnvVar: "XENSERVER_WAIT_TIMEOUT",
			Name:   "xenserver-wait-timeout",
			Usage:  "XenServer wait VM start timeout(seconds)",
			Value:  30 * 60,
		},
                mcnflag.StringFlag{
                        EnvVar: "XENSERVER_OS_TEMPLATE",
                        Name:   "xenserver-os-template",
                        Usage:  "XenServer OS Template Label Name",
			Value:  "Other install media",
                },

	}
}

func NewDriver() *Driver {
	return &Driver{}
}

func (d *Driver) GetMachineName() string {
	return d.MachineName
}

func (d *Driver) GetSSHHostname() (string, error) {
	return d.GetIP()
}

func (d *Driver) GetSSHKeyPath() string {
	return filepath.Join(d.StorePath, "id_rsa")
}

func (d *Driver) GetSSHPort() (int, error) {
	if d.SSHPort == 0 {
		d.SSHPort = 22
	}

	return d.SSHPort, nil
}

func (d *Driver) GetSSHUsername() string {
	if d.SSHUser == "" {
		d.SSHUser = B2D_USER
	}

	return d.SSHUser
}

func (d *Driver) DriverName() string {
	return "xenserver"
}

func (d *Driver) SetConfigFromFlags(flags drivers.DriverOptions) error {
	d.SSHUser = B2D_USER
	d.SSHPort = 22
	d.Server = flags.String("xenserver-server")
	d.Username = flags.String("xenserver-username")
	d.Password = flags.String("xenserver-password")
	d.Boot2DockerURL = flags.String("xenserver-boot2docker-url")
	d.CPU = uint(flags.Int("xenserver-vcpu-count"))
	d.Memory = uint(flags.Int("xenserver-memory-size"))
	d.DiskSize = uint(flags.Int("xenserver-disk-size"))
	d.SR = flags.String("xenserver-sr-label")
	d.Network = flags.String("xenserver-network-label")
	d.Host = flags.String("xenserver-host-label")
	d.UploadTimeout = uint(flags.Int("xenserver-upload-timeout"))
	d.WaitTimeout = uint(flags.Int("xenserver-wait-timeout"))
	d.SwarmMaster = flags.Bool("swarm-master")
	d.SwarmHost = flags.String("swarm-host")
	d.SwarmDiscovery = flags.String("swarm-discovery")
	d.ISO = d.ResolveStorePath(isoFilename)
	d.TAR = d.ResolveStorePath(tarFilename)
	d.osTemplateLabelName = flags.String("xenserver-os-template")

	return nil
}

func (d *Driver) GetURL() (string, error) {
	ip, _ := d.GetIP()
	if ip == "" {
		return "", nil
	}
	return fmt.Sprintf("tcp://%s:2376", ip), nil
}

func (d *Driver) GetIP() (string, error) {
	status, err := d.GetState()
	if err != nil {
		return "", err
	}
	if status != state.Running {
		return "", fmt.Errorf("Docker VM(%v) is not running", d.MachineName)
	}

	// Need Login first if it is a fresh session
	c, err := d.GetXenAPIClient()
	if err != nil {
		return "", err
	}

	// Get doker machine by label name
	vm, err := c.GetUniqueVMByNameLabel(d.MachineName)
	if err != nil {
		return "", err
	}

	// Get docker machine VM metrics
	metrics, err := vm.GetGuestMetrics()
	if err != nil {
		return "", err
	}

	// Get networks metrics
	networks, ok := metrics["networks"]
	if !ok {
		return "", fmt.Errorf("Docker VM(%v) get network metrics error: \"networks\" not presented", d.MachineName)
	}

	net, ok := networks.(xmlrpc.Struct)
	if !ok {
		return "", fmt.Errorf("Docker VM(%v) get network metrics error: \"networks\" is not a xmlrpc.Struct instance", d.MachineName)
	}

	for i := 0; i < len(net); i++ {
		ip, ok := net[fmt.Sprintf("%d/ip", i)]
		if ok && ip != "" {
			return ip.(string), nil
		}
	}

	return "", fmt.Errorf("Docker VM(%v) get ipaddr error", d.MachineName)
}

func (d *Driver) GetState() (state.State, error) {
	var err error

	// Need Login first if it is a fresh session
	c, err := d.GetXenAPIClient()
	if err != nil {
		return state.None, err
	}

	// Get docker machine VM by label name
	vm, err := c.GetUniqueVMByNameLabel(d.MachineName)
	if err != nil {
		return state.None, err
	}

	// Get doker machine VM power state
	powerState, err := vm.GetPowerState()
	if err != nil {
		return state.None, err
	}

	// https://github.com/xapi-project/xen-api/blob/cacbb2d3c5996efbf4cf117ab862439271a8cecd/ocaml/client_records/record_util.ml#L20
	switch strings.ToLower(powerState) {
	case "halted":
		return state.Stopped, nil
	case "paused":
		return state.Paused, nil
	case "running":
		return state.Running, nil
	case "suspended":
		return state.Paused, nil
	case "shutting down":
		return state.Stopping, nil
	case "migrating":
		return state.Running, nil
	}

	return state.None, nil
}

func (d *Driver) PreCreateCheck() error {
	// Downloading boot2docker to cache should be done here to make sure
	// that a download failure will not leave a machine half created.
	b2dutils := mcnutils.NewB2dUtils(d.StorePath)
	if err := b2dutils.UpdateISOCache(d.Boot2DockerURL); err != nil {
		return err
	}

	return nil
}

func (d *Driver) Create() error {
	var err error

	d.setMachineNameIfNotSet()

	b2dutils := mcnutils.NewB2dUtils(d.StorePath)
	if err := b2dutils.CopyIsoToMachineDir(d.Boot2DockerURL, d.MachineName); err != nil {
		return err
	}

	log.Infof("Logging into XenServer %s...", d.Server)
	c, err := d.GetXenAPIClient()
	if err != nil {
		return err
	}

	// Generate SSH Keys
	log.Infof("Creating SSH key...")

	if err := ssh.GenerateSSHKey(d.sshKeyPath()); err != nil {
		return err
	}

	// Only upload ISO image if using Other install media, otherwise use existing VM template
	var sr *xsclient.SR
	var isoVdi,diskVdi *xsclient.VDI
	var isoVdiUuid,diskVdiUuid string

	if d.osTemplateLabelName == "Other install media" {

		log.Infof("Creating ISO VDI...")

		// Get the SR
		if d.SR == "" {
			sr, err = c.GetDefaultSR()
			if sr.Ref == "OpaqueRef:NULL" {
				err := errors.New("No default SR found. Please configure a " +
					"default or specify the SR explicitly using " +
					"--xenserver-sr-label.")
				log.Errorf("%v", err)
				return err
			}
		} else {
			sr, err = c.GetUniqueSRByNameLabel(d.SR)
		}
		if err != nil {
			return err
		}

		isoFileInfo, err := os.Stat(d.ISO)
		if err != nil {
			return err
		}

		// Create the VDI
		isoVdi, err = sr.CreateVdi(isoFilename, isoFileInfo.Size())
		if err != nil {
			log.Errorf("Unable to create ISO VDI '%s': %v", isoFilename, err)
			return err
		}

		// Import the VDI
		if err = d.importVdi(isoVdi, d.ISO, time.Duration(d.UploadTimeout)*time.Second); err != nil {
			return err
		}

		isoVdiUuid, err = isoVdi.GetUuid()
		if err != nil {
			return err
		}

		log.Infof("Creating Disk VDI...")
		err = d.generateDiskImage()
		if err != nil {
			return err
		}

		// Create the VDI
		diskVdi, err = sr.CreateVdi("bootdocker disk", int64(d.DiskSize)*1024*1024)
		if err != nil {
			log.Errorf("Unable to create ISO VDI '%s': %v", "bootdocker disk", err)
			return err
		}
		if err = d.importVdi(diskVdi, d.TAR, time.Duration(d.UploadTimeout)*time.Second); err != nil {
			return err
		}

		diskVdiUuid, err = diskVdi.GetUuid()
		if err != nil {
			return err
		}

	}

	log.Infof("Creating VM...")

	vm0, err := c.GetUniqueVMByNameLabel(d.osTemplateLabelName)
	if err != nil {
		return err
	}

	// Clone VM from VM template
	vm, err := vm0.Clone(fmt.Sprintf("__gui__%s", d.MachineName))
	if err != nil {
		return err
	}

	vmMacSeed, err := pseudoUuid()
	if err != nil {
		return err
	}

	hostname, err := os.Hostname()
	if err != nil {
		log.Errorf("Unable get local hostname")
	}

	otherConfig := map[string]string{
		"base_template_name":     d.osTemplateLabelName,
		"install-methods":        "cdrom,nfs,http,ftp",
		"linux_template":         "true",
		"mac_seed":               vmMacSeed,
		"docker-machine-creator": hostname,
	}
	err = vm.SetOtherConfig(otherConfig)
	if err != nil {
		return err
	}

	log.Infof("Provision VM...")
	err = vm.Provision()
	if err != nil {
		return err
	}

	// Set machine name
	err = vm.SetNameLabel(d.MachineName)
	if err != nil {
		return err
	}

	// Set vCPU number
	err = vm.SetVCPUsMax(d.CPU)
	if err != nil {
		return err
	}

	err = vm.SetVCPUsAtStartup(d.CPU)
	if err != nil {
		return err
	}

	platform_params := map[string]string{
		"acpi":             "1",
		"apic":             "true",
		"cores-per-socket": "1",
		"device_id":        "0001",
		"nx":               "true",
		"pae":              "true",
		"vga":              "std",
		"videoram":         "8",
		"viridian":         "false",
	}
	err = vm.SetPlatform(platform_params)
	if err != nil {
		return err
	}

	// Set machine memory size
	err = vm.SetStaticMemoryRange(uint64(d.Memory)*1024*1024, uint64(d.Memory)*1024*1024)
	if err != nil {
		return err
	}

	if d.osTemplateLabelName == "Other install media" {
		log.Infof("Add ISO VDI to VM...")
		diskVdi, err = c.GetVdiByUuid(isoVdiUuid)
		if err != nil {
			return err
		}

		err = vm.ConnectVdi(diskVdi, xsclient.Disk, "0")
		if err != nil {
			return err
		}

		log.Infof("Add Disk VDI to VM...")
		diskVdi, err = c.GetVdiByUuid(diskVdiUuid)
		if err != nil {
			return err
		}

		err = vm.ConnectVdi(diskVdi, xsclient.Disk, "1")
		if err != nil {
			return err
		}
	}

	log.Infof("Add Network to VM...")
	var networks []*xsclient.Network
	if d.Network == "" {
		networks1, err := c.GetNetworks()
		if err != nil {
			return err
		}
		for _, network := range networks1 {
			otherConfig, err := network.GetOtherConfig()
			if err != nil {
				return err
			}
			isInternal, ok := otherConfig["is_host_internal_management_network"]
			if ok && isInternal == "true" {
				continue
			}
			automaitc, ok := otherConfig["automatic"]
			if ok && automaitc == "false" {
				continue
			}
			networks = append(networks, network)
		}
	} else {
		network, err := c.GetUniqueNetworkByNameLabel(d.Network)
		if err != nil {
			return err
		}
		networks = append(networks, network)
	}
	if len(networks) == 0 {
		return fmt.Errorf("Unable get available networks for %v", d.MachineName)
	}

	vifDevices, err := vm.GetAllowedVIFDevices()
	if err != nil {
		return err
	}
	if len(vifDevices) < len(networks) {
		log.Warnf("VM(%s) networks number is limited to %d.", d.MachineName, len(vifDevices))
		networks = networks[:len(vifDevices)]
	}

	for i, network := range networks {
		_, err = vm.ConnectNetwork(network, vifDevices[i])
		if err != nil {
			return err
		}
	}

	log.Infof("Starting VM...")
	if d.Host == "" {
		if err = vm.Start(false, false); err != nil {
			return err
		}
	} else {
		host, err := c.GetUniqueHostByNameLabel(d.Host)
		if err != nil {
			return err
		}
		if err = vm.StartOn(host, false, false); err != nil {
			return err
		}
	}

	if err := d.wait(time.Duration(d.WaitTimeout) * time.Second); err != nil {
		return err
	}

	log.Infof("VM Created.")

	return nil
}

func (d *Driver) wait(timeout time.Duration) (err error) {
	log.Infof("Waiting for VM to start...")

	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()

	out := make(chan error, 1)
	go func(ctx context.Context, out chan<- error) {
		var ip string
		for {
			ip, _ = d.GetIP()
			if ip != "" {
				break
			}
			if t, ok := ctx.Deadline(); ok && time.Now().After(t) {
				out <- fmt.Errorf("Wait GetIP timed out")
				return
			}
			time.Sleep(1 * time.Second)
		}

		port, err := d.GetSSHPort()
		if err != nil {
			out <- err
			return
		}

		addr := fmt.Sprintf("%s:%d", ip, port)
		log.Infof("Got VM address(%v), Now waiting for SSH", addr)
		out <- drivers.WaitForSSH(d)
	}(ctx, out)

	select {
	case err := <-out:
		return err
	case <-ctx.Done():
		return fmt.Errorf("Wait for VM to start timed out: %v", ctx.Err())
	}

	return nil
}

func (d *Driver) Start() error {
	var err error

	c, err := d.GetXenAPIClient()
	if err != nil {
		return err
	}

	vm, err := c.GetUniqueVMByNameLabel(d.MachineName)
	if err != nil {
		return err
	}

	if err = vm.Start(false, true); err != nil {
		return err
	}
	if err = d.wait(time.Duration(d.WaitTimeout) * time.Second); err != nil {
		return err
	}

	return nil
}

func (d *Driver) Stop() error {
	var err error

	c, err := d.GetXenAPIClient()
	if err != nil {
		return err
	}

	vm, err := c.GetUniqueVMByNameLabel(d.MachineName)
	if err != nil {
		return err
	}

	if err = vm.CleanShutdown(); err != nil {
		return err
	}

	return nil
}

func (d *Driver) Remove() error {
	var err error

	c, err := d.GetXenAPIClient()
	if err != nil {
		return err
	}

	vm, err := c.GetUniqueVMByNameLabel(d.MachineName)
	if err != nil {
		return err
	}

	vmState, err := d.GetState()
	if err != nil {
		return err
	}

	switch vmState {
	case state.None:
		return fmt.Errorf("Unable get VM(%v) state.", d.MachineName)
	case state.Stopping:
		return fmt.Errorf("VM(%v) state is stopping, please wait.", d.MachineName)
	case state.Stopped:
		break
	case state.Paused:
		if err = vm.HardShutdown(); err != nil {
			return err
		}
	default:
		if err = vm.CleanShutdown(); err != nil {
			if err = vm.HardShutdown(); err != nil {
				return err
			}
		}
	}

	disks, err := vm.GetDisks()
	if err != nil {
		return err
	}

	for _, disk := range disks {
		if err = disk.Destroy(); err != nil {
			return err
		}
	}

	if err = vm.Destroy(); err != nil {
		return err
	}

	return nil
}

func (d *Driver) Restart() error {
	if err := d.Stop(); err != nil {
		return err
	}

	return d.Start()
}

func (d *Driver) Kill() error {
	var err error

	c, err := d.GetXenAPIClient()
	if err != nil {
		return err
	}

	vm, err := c.GetUniqueVMByNameLabel(d.MachineName)
	if err != nil {
		return err
	}

	if err = vm.HardShutdown(); err != nil {
		return err
	}
	return nil
}

func (d *Driver) setMachineNameIfNotSet() {
	if d.MachineName == "" {
		d.MachineName = fmt.Sprintf("docker-machine-unknown")
	}
}

func (d *Driver) sshKeyPath() string {
	return filepath.Join(d.StorePath, "id_rsa")
}

func (d *Driver) publicSSHKeyPath() string {
	return d.sshKeyPath() + ".pub"
}

// Make a boot2docker VM disk image.
func (d *Driver) generateDiskImage() error {
	magicString := "boot2docker, please format-me"

	buf := new(bytes.Buffer)
	tw := tar.NewWriter(buf)

	log.Infof("Generate Disk Image...")
	// magicString first so the automount script knows to format the disk
	file := &tar.Header{Name: magicString, Size: int64(len(magicString))}
	if err := tw.WriteHeader(file); err != nil {
		return err
	}
	if _, err := tw.Write([]byte(magicString)); err != nil {
		return err
	}
	// .ssh/key.pub => authorized_keys
	file = &tar.Header{Name: ".ssh", Typeflag: tar.TypeDir, Mode: 0700}
	if err := tw.WriteHeader(file); err != nil {
		return err
	}
	pubKey, err := ioutil.ReadFile(d.publicSSHKeyPath())
	if err != nil {
		return err
	}
	file = &tar.Header{Name: ".ssh/authorized_keys", Size: int64(len(pubKey)), Mode: 0644}
	if err := tw.WriteHeader(file); err != nil {
		return err
	}
	if _, err := tw.Write([]byte(pubKey)); err != nil {
		return err
	}
	file = &tar.Header{Name: ".ssh/authorized_keys2", Size: int64(len(pubKey)), Mode: 0644}
	if err := tw.WriteHeader(file); err != nil {
		return err
	}
	if _, err := tw.Write([]byte(pubKey)); err != nil {
		return err
	}
	if err := tw.Close(); err != nil {
		return err
	}
	if err := ioutil.WriteFile(d.TAR, buf.Bytes(), 0644); err != nil {
		return err
	}
	return nil
}

func (d *Driver) GetXenAPIClient() (*XenAPIClient, error) {
	if d.xenAPIClient == nil {
		c := NewXenAPIClient(d.Server, d.Username, d.Password)
		if err := c.Login(); err != nil {
			return nil, err
		}
		d.xenAPIClient = &c
	}
	return d.xenAPIClient, nil
}

func (d *Driver) importVdi(vdi *xsclient.VDI, filename string, timeout time.Duration) error {
	f, err := os.Open(filename)
	if err != nil {
		log.Errorf("Unable to open disk image '%s': %v", filename, err)
		return err
	}

	// Get file length
	fi, err := f.Stat()
	if err != nil {
		log.Errorf("Unable to stat disk image '%s': %v", filename, err)
		return err
	}

	task, err := vdi.Client.CreateTask()
	if err != nil {
		return fmt.Errorf("Unable to create task: %v", err)
	}
	urlStr := fmt.Sprintf("https://%s/import_raw_vdi?vdi=%s&session_id=%s&task_id=%s",
		vdi.Client.Host, vdi.Ref, vdi.Client.Session.(string), task.Ref)

	// Define a new http Transport which allows self-signed certs
	tr := &http.Transport{
		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
	}

	req, err := http.NewRequest("PUT", urlStr, f)
	if err != nil {
		return err
	}
	req.ContentLength = fi.Size()

	resp, err := tr.RoundTrip(req)
	if err != nil {
		log.Errorf("Unable to upload VDI: %v", err)
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		msg, _ := ioutil.ReadAll(resp.Body)
		err = fmt.Errorf("xenserver reply %s: %v", resp.Status, string(msg))
		log.Errorf("Unable to upload VDI: %v", err)
		return err
	}

	log.Infof("Waiting Upload VDI task(%v) to complete...", task.Ref)
	if err = d.waitTask(task, timeout); err != nil {
		return err
	}
	return nil
}

func (d *Driver) waitTask(task *xsclient.Task, timeout time.Duration) error {
	timeout_at := time.Now().Add(timeout)

	for {
		status, err := task.GetStatus()
		if err != nil {
			return fmt.Errorf("Failed to get task status: %s", err.Error())
		}

		if status == xsclient.Success {
			log.Infof("Upload VDI task(%s) completed", task.Ref)
			break
		}

		switch status {
		case xsclient.Pending:
			progress, err := task.GetProgress()
			if err != nil {
				return fmt.Errorf("Failed to get progress: %s", err.Error())
			}
			log.Debugf("Upload %.0f%% complete", progress*100)
			log.Infof("Uploading...")
		case xsclient.Failure:
			errorInfo, err := task.GetErrorInfo()
			if err != nil {
				errorInfo = []string{fmt.Sprintf("furthermore, failed to get error info: %s", err.Error())}
			}
			return fmt.Errorf("Task failed: %s", errorInfo)
		case xsclient.Cancelling, xsclient.Cancelled:
			return fmt.Errorf("Task Cancelled")
		default:
			return fmt.Errorf("Unknown task status %v", status)
		}

		if time.Now().After(timeout_at) {
			return fmt.Errorf("Upload VDI task(%s) timed out", task.Ref)
		}

		time.Sleep(5 * time.Second)
	}

	return nil
}

func pseudoUuid() (string, error) {
	b := make([]byte, 16)
	_, err := io.ReadFull(rand.Reader, b)
	if err != nil {
		return "", err
	}
	uuid := fmt.Sprintf("%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
	return uuid, nil
}