Add `debug_mode` to PowerShell provisioner (#8996)

provisioner/powershell/provisioner.go

@@ -78,6 +78,15 @@ type Config struct {
 
 	remoteCleanUpScriptPath string
 
+	// If set, sets PowerShell's [PSDebug mode](https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/set-psdebug?view=powershell-7)
+	//  in order to make script debugging easier. For instance, setting the
+	//    value to 1 results in adding this to the execute command:
+	//
+	//    ``` powershell
+	//    Set-PSDebug -Trace 1
+	//    ```
+	DebugMode int `mapstructure:"debug_mode"`
+
 	ctx interpolate.Context
 }
 
@@ -89,8 +98,13 @@ type Provisioner struct {
 
 func (p *Provisioner) defaultExecuteCommand() string {
 	baseCmd := `& { if (Test-Path variable:global:ProgressPreference)` +
-		`{set-variable -name variable:global:ProgressPreference -value 'SilentlyContinue'};` +
-		`. {{.Vars}}; &'{{.Path}}'; exit $LastExitCode }`
+		`{set-variable -name variable:global:ProgressPreference -value 'SilentlyContinue'};`
+
+	if p.config.DebugMode != 0 {
+		baseCmd += fmt.Sprintf(`Set-PsDebug -Trace %d;`, p.config.DebugMode)
+	}
+
+	baseCmd += `. {{.Vars}}; &'{{.Path}}'; exit $LastExitCode }`
 
 	if p.config.ExecutionPolicy == ExecutionPolicyNone {
 		return baseCmd
@@ -208,6 +222,10 @@ func (p *Provisioner) Prepare(raws ...interface{}) error {
 			`"unrestricted", "none".`))
 	}
 
+	if !(p.config.DebugMode >= 0 && p.config.DebugMode <= 2) {
+		errs = packer.MultiErrorAppend(errs, fmt.Errorf("%d is an invalid Trace level for `debug_mode`; valid values are 0, 1, and 2", p.config.DebugMode))
+	}
+
 	if errs != nil {
 		return errs
 	}

provisioner/powershell/provisioner.hcl2spec.go

@@ -33,6 +33,7 @@ type FlatConfig struct {
 	ElevatedUser           *string           `mapstructure:"elevated_user" cty:"elevated_user"`
 	ElevatedPassword       *string           `mapstructure:"elevated_password" cty:"elevated_password"`
 	ExecutionPolicy        *string           `mapstructure:"execution_policy" cty:"execution_policy"`
+	DebugMode              *int              `mapstructure:"debug_mode" cty:"debug_mode"`
 }
 
 // FlatMapstructure returns a new FlatConfig.
@@ -71,6 +72,7 @@ func (*FlatConfig) HCL2Spec() map[string]hcldec.Spec {
 		"elevated_user":              &hcldec.AttrSpec{Name: "elevated_user", Type: cty.String, Required: false},
 		"elevated_password":          &hcldec.AttrSpec{Name: "elevated_password", Type: cty.String, Required: false},
 		"execution_policy":           &hcldec.AttrSpec{Name: "execution_policy", Type: cty.String, Required: false},
+		"debug_mode":                 &hcldec.AttrSpec{Name: "debug_mode", Type: cty.Number, Required: false},
 	}
 	return s
 }

provisioner/powershell/provisioner_test.go

@@ -104,7 +104,38 @@ func TestProvisionerPrepare_Config(t *testing.T) {
 	if p.config.ElevatedPassword != "mypassword" {
 		t.Fatalf("Expected 'mypassword' for key `elevated_password`: %s", p.config.ElevatedPassword)
 	}
+}
 
+func TestProvisionerPrepare_DebugMode(t *testing.T) {
+	config := testConfig()
+	config["debug_mode"] = 1
+
+	var p Provisioner
+	err := p.Prepare(config)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	command := `powershell -executionpolicy bypass "& { if (Test-Path variable:global:ProgressPreference){set-variable -name variable:global:ProgressPreference -value 'SilentlyContinue'};Set-PsDebug -Trace 1;. {{.Vars}}; &'{{.Path}}'; exit $LastExitCode }"`
+	if p.config.ExecuteCommand != command {
+		t.Fatalf(fmt.Sprintf(`Expected command should be '%s' but got '%s'`, command, p.config.ExecuteCommand))
+	}
+}
+
+func TestProvisionerPrepare_InvalidDebugMode(t *testing.T) {
+	config := testConfig()
+	config["debug_mode"] = -1
+
+	var p Provisioner
+	err := p.Prepare(config)
+	if err == nil {
+		t.Fatalf("should have error")
+	}
+
+	message := "invalid Trace level for `debug_mode`; valid values are 0, 1, and 2"
+	if !strings.Contains(err.Error(), message) {
+		t.Fatalf("expected Prepare() error %q to contain %q", err.Error(), message)
+	}
 }
 
 func TestProvisionerPrepare_InvalidKey(t *testing.T) {

website/pages/docs/provisioners/powershell.mdx

@@ -33,6 +33,13 @@ The example below is fully functional.
 
 @include 'provisioners/shell-config.mdx'
 
+- `debug_mode` - If set, sets PowerShell's [PSDebug mode](https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/set-psdebug?view=powershell-7)
+   in order to make script debugging easier. For instance, setting the value to 1 results in adding this to the execute command:
+
+     ``` powershell
+     Set-PSDebug -Trace 1
+     ```
+
 - `elevated_execute_command` (string) - The command to use to execute the
   elevated script. By default this is as follows: