Windows: Default to Hyper-V Containers on client

Signed-off-by: John Howard <jhoward@microsoft.com>

system/syscall_windows.go

@@ -3,10 +3,13 @@ package system
 import (
 	"syscall"
 	"unsafe"
+
+	"github.com/Sirupsen/logrus"
 )
 
 var (
-	ntuserApiset = syscall.NewLazyDLL("ext-ms-win-ntuser-window-l1-1-0")
+	ntuserApiset      = syscall.NewLazyDLL("ext-ms-win-ntuser-window-l1-1-0")
+	procGetVersionExW = modkernel32.NewProc("GetVersionExW")
 )
 
 // OSVersion is a wrapper for Windows version information
@@ -18,6 +21,21 @@ type OSVersion struct {
 	Build        uint16
 }
 
+// https://msdn.microsoft.com/en-us/library/windows/desktop/ms724833(v=vs.85).aspx
+type osVersionInfoEx struct {
+	OSVersionInfoSize uint32
+	MajorVersion      uint32
+	MinorVersion      uint32
+	BuildNumber       uint32
+	PlatformID        uint32
+	CSDVersion        [128]uint16
+	ServicePackMajor  uint16
+	ServicePackMinor  uint16
+	SuiteMask         uint16
+	ProductType       byte
+	Reserve           byte
+}
+
 // GetOSVersion gets the operating system version on Windows. Note that
 // docker.exe must be manifested to get the correct version information.
 func GetOSVersion() OSVersion {
@@ -34,6 +52,18 @@ func GetOSVersion() OSVersion {
 	return osv
 }
 
+// IsWindowsClient returns true if the SKU is client
+func IsWindowsClient() bool {
+	osviex := &osVersionInfoEx{OSVersionInfoSize: 284}
+	r1, _, err := procGetVersionExW.Call(uintptr(unsafe.Pointer(osviex)))
+	if r1 == 0 {
+		logrus.Warnf("GetVersionExW failed - assuming server SKU: %v", err)
+		return false
+	}
+	const verNTWorkstation = 0x00000001
+	return osviex.ProductType == verNTWorkstation
+}
+
 // Unmount is a platform-specific helper function to call
 // the unmount syscall. Not supported on Windows
 func Unmount(dest string) error {