Refactor the export step for Hyper-V ISO and VMCX builders

* Fixes a bug that caused the build to error if users did not
  explicitly set `skip_compaction:true` when setting `skip_export:
  true`. See #6392.
* Improves the efficiency of the compaction and export process by
  reordering the compaction and export steps.
* Further improves the efficiency of the compacting step through
  compacting the vmd* file directly rather than creating and then
  operating on a copy.
* The changes mean the export process now stores the exported machine
  files and folders under a folder with name 'vm_name' in the output
  directory. Previously the exported machine files and folders were
  stored directly in the output directory.

builder/hyperv/common/driver.go

@@ -94,7 +94,7 @@ type Driver interface {
 
 	ExportVirtualMachine(string, string) error
 
-	CompactDisks(string, string) error
+	CompactDisks(string) error
 
 	CopyExportedVirtualMachine(string, string, string, string) error
 

builder/hyperv/common/driver_mock.go

@@ -187,8 +187,7 @@ type DriverMock struct {
 	ExportVirtualMachine_Err    error
 
 	CompactDisks_Called bool
-	CompactDisks_ExpPath string
-	CompactDisks_VhdDir  string
+	CompactDisks_Path   string
 	CompactDisks_Err    error
 
 	CopyExportedVirtualMachine_Called     bool
@@ -489,10 +488,9 @@ func (d *DriverMock) ExportVirtualMachine(vmName string, path string) error {
 	return d.ExportVirtualMachine_Err
 }
 
-func (d *DriverMock) CompactDisks(expPath string, vhdDir string) error {
+func (d *DriverMock) CompactDisks(path string) error {
 	d.CompactDisks_Called = true
-	d.CompactDisks_ExpPath = expPath
-	d.CompactDisks_VhdDir = vhdDir
+	d.CompactDisks_Path = path
 	return d.CompactDisks_Err
 }
 

builder/hyperv/common/driver_ps_4.go

@@ -219,8 +219,8 @@ func (d *HypervPS4Driver) ExportVirtualMachine(vmName string, path string) error
 	return hyperv.ExportVirtualMachine(vmName, path)
 }
 
-func (d *HypervPS4Driver) CompactDisks(expPath string, vhdDir string) error {
-	return hyperv.CompactDisks(expPath, vhdDir)
+func (d *HypervPS4Driver) CompactDisks(path string) error {
+	return hyperv.CompactDisks(path)
 }
 
 func (d *HypervPS4Driver) CopyExportedVirtualMachine(expPath string, outputPath string, vhdDir string, vmDir string) error {

builder/hyperv/common/step_export_vm.go

@@ -3,18 +3,11 @@ package common
 import (
 	"context"
 	"fmt"
-	"io/ioutil"
-	"path/filepath"
 
 	"github.com/hashicorp/packer/helper/multistep"
 	"github.com/hashicorp/packer/packer"
 )
 
-const (
-	vhdDir string = "Virtual Hard Disks"
-	vmDir  string = "Virtual Machines"
-)
-
 type StepExportVm struct {
 	OutputDir      string
 	SkipCompaction bool
@@ -24,63 +17,48 @@ type StepExportVm struct {
 func (s *StepExportVm) Run(_ context.Context, state multistep.StateBag) multistep.StepAction {
 	driver := state.Get("driver").(Driver)
 	ui := state.Get("ui").(packer.Ui)
-	var err error
-	var errorMsg string
 
-	vmName := state.Get("vmName").(string)
-	tmpPath := state.Get("packerTempDir").(string)
-	outputPath := s.OutputDir
-	expPath := s.OutputDir
-
-	// create temp path to export vm
-	errorMsg = "Error creating temp export path: %s"
-	vmExportPath, err := ioutil.TempDir(tmpPath, "export")
-	if err != nil {
-		err := fmt.Errorf(errorMsg, err)
-		state.Put("error", err)
-		ui.Error(err.Error())
-		return multistep.ActionHalt
+	// Get the VM name; Get the temp directory used to store the VMs files
+	// during the build process
+	var vmName, tmpPath string
+	if v, ok := state.GetOk("vmName"); ok {
+		vmName = v.(string)
 	}
-	if !s.SkipExport {
-		ui.Say("Exporting vm...")
-
-		err = driver.ExportVirtualMachine(vmName, vmExportPath)
-		if err != nil {
-			errorMsg = "Error exporting vm: %s"
-			err := fmt.Errorf(errorMsg, err)
-			state.Put("error", err)
-			ui.Error(err.Error())
-			return multistep.ActionHalt
-		}
-		// copy to output dir
-		expPath = filepath.Join(vmExportPath, vmName)
+	if v, ok := state.GetOk("packerTempDir"); ok {
+		tmpPath = v.(string)
 	}
 
+	// Compact disks first so the export process has less to do
 	if s.SkipCompaction {
 		ui.Say("Skipping disk compaction...")
 	} else {
 		ui.Say("Compacting disks...")
-		err = driver.CompactDisks(expPath, vhdDir)
+		err := driver.CompactDisks(tmpPath)
 		if err != nil {
-			errorMsg = "Error compacting disks: %s"
-			err := fmt.Errorf(errorMsg, err)
+			err := fmt.Errorf("Error compacting disks: %s", err)
 			state.Put("error", err)
 			ui.Error(err.Error())
 			return multistep.ActionHalt
 		}
 	}
 
-	if !s.SkipExport {
-		ui.Say("Copying to output dir...")
-		err = driver.CopyExportedVirtualMachine(expPath, outputPath, vhdDir, vmDir)
+	if s.SkipExport {
+		ui.Say("Skipping export of virtual machine...")
+		return multistep.ActionContinue
+	}
+
+	ui.Say("Exporting virtual machine...")
+	// The export process exports the VM to a folder named 'vmName' under
+	// the output directory. This contains the usual 'Snapshots', 'Virtual
+	// Hard Disks' and 'Virtual Machines' directories.
+	err := driver.ExportVirtualMachine(vmName, s.OutputDir)
 	if err != nil {
-			errorMsg = "Error exporting vm: %s"
-			err := fmt.Errorf(errorMsg, err)
+		err = fmt.Errorf("Error exporting vm: %s", err)
 		state.Put("error", err)
 		ui.Error(err.Error())
 		return multistep.ActionHalt
 	}
-	}
+
 	return multistep.ActionContinue
 }
 

common/powershell/hyperv/hyperv.go

@@ -665,16 +665,16 @@ if (Test-Path -Path ([IO.Path]::Combine($path, $vmName, 'Virtual Machines', '*.V
 	return err
 }
 
-func CompactDisks(expPath string, vhdDir string) error {
+func CompactDisks(path string) error {
 	var script = `
-param([string]$srcPath, [string]$vhdDirName)
-Get-ChildItem "$srcPath/$vhdDirName" -Filter *.vhd* | %{
+param([string]$srcPath)
+Get-ChildItem "$srcPath" -Filter *.vhd* | %{
     Optimize-VHD -Path $_.FullName -Mode Full
 }
 `
 
 	var ps powershell.PowerShellCmd
-	err := ps.Run(script, expPath, vhdDir)
+	err := ps.Run(script, path)
 	return err
 }