Enable cache image for Windows

pkg/minikube/machine/cache_images.go

@@ -19,6 +19,7 @@ package machine
 import (
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"runtime"
 	"strings"
@@ -122,6 +123,32 @@ func hasWindowsDriveLetter(s string) bool {
 	return false
 }
 
+func getWindowsVolumeName(d string) (string, error) {
+	cmd := exec.Command("wmic", "volume", "where", "DriveLetter = '"+d+":'", "get", "DeviceID")
+
+	stdout, err := cmd.Output()
+	if err != nil {
+		return "", err
+	}
+
+	outs := strings.Split(strings.Replace(string(stdout), "\r", "", -1), "\n")
+
+	var vname string
+	for _, l := range outs {
+		s := strings.TrimSpace(l)
+		if strings.HasPrefix(s, `\\?\Volume{`) && strings.HasSuffix(s, `}\`) {
+			vname = s
+			break
+		}
+	}
+
+	if vname == "" {
+		return "", errors.New("failed to get a volume GUID")
+	}
+
+	return vname, nil
+}
+
 func LoadFromCacheBlocking(cmd bootstrapper.CommandRunner, src string) error {
 	glog.Infoln("Loading image from cache at ", src)
 	filename := filepath.Base(src)
@@ -162,6 +189,18 @@ func getSrcRef(image string) (types.ImageReference, error) {
 }
 
 func getDstRef(image, dst string) (types.ImageReference, error) {
+	if hasWindowsDriveLetter(dst) {
+		// ParseReference does not support a Windows drive letter.
+		// Therefore, will change the drive letter to a volume name.
+		vname, err := getWindowsVolumeName(dst[:1])
+		if err != nil {
+			return nil, errors.Wrap(err, "parsing docker archive dst ref: get Windows volume name")
+		}
+		dst = vname + dst[3:]
+		if _, err := os.Stat(filepath.Dir(dst)); err != nil {
+			return nil, errors.Wrap(err, "parsing docker archive dst ref: get Windows volume name")
+		}
+	}
 	dstRef, err := archive.ParseReference(dst + ":" + image)
 	if err != nil {
 		return nil, errors.Wrap(err, "parsing docker archive dst ref")
@@ -179,13 +218,6 @@ func CacheImage(image, dst string) error {
 		return errors.Wrapf(err, "making cache image directory: %s", dst)
 	}
 
-	// TODO: support Windows drive letter.
-	// L:164 ParseReference does not support Windows drive letter.
-	// If contains Windows drive letter, it disable cache image for now.
-	if hasWindowsDriveLetter(dst) {
-		return nil
-	}
-
 	srcRef, err := getSrcRef(image)
 	if err != nil {
 		return errors.Wrap(err, "creating docker image src ref")