Enable use of separate temp path for Hyper-V VHD

.gitignore

@@ -22,3 +22,4 @@ packer-test*.log
 .idea/
 *.iml
 Thumbs.db
+/packer.exe

builder/hyperv/common/driver.go

@@ -64,7 +64,7 @@ type Driver interface {
 
 	DeleteVirtualSwitch(string) error
 
-	CreateVirtualMachine(string, string, int64, int64, string, uint) error
+	CreateVirtualMachine(string, string, string, int64, int64, string, uint) error
 
 	DeleteVirtualMachine(string) error
 

builder/hyperv/common/driver_ps_4.go

@@ -166,8 +166,8 @@ func (d *HypervPS4Driver) CreateVirtualSwitch(switchName string, switchType stri
 	return hyperv.CreateVirtualSwitch(switchName, switchType)
 }
 
-func (d *HypervPS4Driver) CreateVirtualMachine(vmName string, path string, ram int64, diskSize int64, switchName string, generation uint) error {
+func (d *HypervPS4Driver) CreateVirtualMachine(vmName string, path string, vhdPath string, ram int64, diskSize int64, switchName string, generation uint) error {
-	return hyperv.CreateVirtualMachine(vmName, path, ram, diskSize, switchName, generation)
+	return hyperv.CreateVirtualMachine(vmName, path, vhdPath, ram, diskSize, switchName, generation)
 }
 
 func (d *HypervPS4Driver) DeleteVirtualMachine(vmName string) error {

builder/hyperv/common/step_create_tempdir.go

@@ -11,6 +11,7 @@ import (
 
 type StepCreateTempDir struct {
 	TempPath    string
+	VhdTempPath string
 	dirPath     string
 }
 
@@ -34,6 +35,22 @@ func (s *StepCreateTempDir) Run(state multistep.StateBag) multistep.StepAction {
 	s.dirPath = packerTempDir
 	state.Put("packerTempDir", packerTempDir)
 
+	if s.VhdTempPath == "" {
+		// Fall back to regular temp dir if no separate VHD temp dir set.
+		state.Put("packerVhdTempDir", packerTempDir)
+	} else {
+		packerVhdTempDir, err := ioutil.TempDir(s.VhdTempPath, "packerhv-vhd")
+		if err != nil {
+			err := fmt.Errorf("Error creating temporary VHD directory: %s", err)
+			state.Put("error", err)
+			ui.Error(err.Error())
+			return multistep.ActionHalt
+		}
+
+		s.dirPath = packerVhdTempDir
+		state.Put("packerVhdTempDir", packerVhdTempDir)
+	}
+
 	//	ui.Say("packerTempDir = '" + packerTempDir + "'")
 
 	return multistep.ActionContinue

builder/hyperv/common/step_create_vm.go

@@ -30,12 +30,13 @@ func (s *StepCreateVM) Run(state multistep.StateBag) multistep.StepAction {
 	ui.Say("Creating virtual machine...")
 
 	path := state.Get("packerTempDir").(string)
+	vhdPath := state.Get("packerVhdTempDir").(string)
 
 	// convert the MB to bytes
 	ramSize := int64(s.RamSize * 1024 * 1024)
 	diskSize := int64(s.DiskSize * 1024 * 1024)
 
-	err := driver.CreateVirtualMachine(s.VMName, path, ramSize, diskSize, s.SwitchName, s.Generation)
+	err := driver.CreateVirtualMachine(s.VMName, path, vhdPath, ramSize, diskSize, s.SwitchName, s.Generation)
 	if err != nil {
 		err := fmt.Errorf("Error creating virtual machine: %s", err)
 		state.Put("error", err)

builder/hyperv/iso/builder.go

@@ -82,6 +82,11 @@ type Config struct {
 	EnableVirtualizationExtensions bool     `mapstructure:"enable_virtualization_extensions"`
 	TempPath                       string   `mapstructure:"temp_path"`
 
+	// A separate path can be used for storing the VM's disk image. The purpose is to enable
+	// reading and writing to take place on different physical disks (read from VHD temp path
+	// write to regular temp path while exporting the VM) to eliminate a single-disk bottleneck.
+	VhdTempPath string `mapstructure:"vhd_temp_path"`
+
 	Communicator string `mapstructure:"communicator"`
 
 	SkipCompaction bool `mapstructure:"skip_compaction"`
@@ -297,6 +302,7 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 	steps := []multistep.Step{
 		&hypervcommon.StepCreateTempDir{
 			TempPath:    b.config.TempPath,
+			VhdTempPath: b.config.VhdTempPath,
 		},
 		&hypervcommon.StepOutputDir{
 			Force: b.config.PackerForce,

common/powershell/hyperv/hyperv.go

@@ -187,27 +187,27 @@ Set-VMFloppyDiskDrive -VMName $vmName -Path $null
 	return err
 }
 
-func CreateVirtualMachine(vmName string, path string, ram int64, diskSize int64, switchName string, generation uint) error {
+func CreateVirtualMachine(vmName string, path string, vhdRoot string, ram int64, diskSize int64, switchName string, generation uint) error {
 
 	if generation == 2 {
 		var script = `
-param([string]$vmName, [string]$path, [long]$memoryStartupBytes, [long]$newVHDSizeBytes, [string]$switchName, [int]$generation)
+param([string]$vmName, [string]$path, [string]$vhdRoot, [long]$memoryStartupBytes, [long]$newVHDSizeBytes, [string]$switchName, [int]$generation)
 $vhdx = $vmName + '.vhdx'
-$vhdPath = Join-Path -Path $path -ChildPath $vhdx
+$vhdPath = Join-Path -Path $vhdRoot -ChildPath $vhdx
 New-VM -Name $vmName -Path $path -MemoryStartupBytes $memoryStartupBytes -NewVHDPath $vhdPath -NewVHDSizeBytes $newVHDSizeBytes -SwitchName $switchName -Generation $generation
 `
 		var ps powershell.PowerShellCmd
-		err := ps.Run(script, vmName, path, strconv.FormatInt(ram, 10), strconv.FormatInt(diskSize, 10), switchName, strconv.FormatInt(int64(generation), 10))
+		err := ps.Run(script, vmName, path, vhdRoot, strconv.FormatInt(ram, 10), strconv.FormatInt(diskSize, 10), switchName, strconv.FormatInt(int64(generation), 10))
 		return err
 	} else {
 		var script = `
-param([string]$vmName, [string]$path, [long]$memoryStartupBytes, [long]$newVHDSizeBytes, [string]$switchName)
+param([string]$vmName, [string]$path, [string]$vhdRoot, [long]$memoryStartupBytes, [long]$newVHDSizeBytes, [string]$switchName)
 $vhdx = $vmName + '.vhdx'
-$vhdPath = Join-Path -Path $path -ChildPath $vhdx
+$vhdPath = Join-Path -Path $vhdRoot -ChildPath $vhdx
 New-VM -Name $vmName -Path $path -MemoryStartupBytes $memoryStartupBytes -NewVHDPath $vhdPath -NewVHDSizeBytes $newVHDSizeBytes -SwitchName $switchName
 `
 		var ps powershell.PowerShellCmd
-		err := ps.Run(script, vmName, path, strconv.FormatInt(ram, 10), strconv.FormatInt(diskSize, 10), switchName)
+		err := ps.Run(script, vmName, path, vhdRoot, strconv.FormatInt(ram, 10), strconv.FormatInt(diskSize, 10), switchName)
 
 		if err != nil {
 			return err