Create new step ManualMountCommand and add to chroot builder

Author: dwc0011

builder/azure/chroot/builder.go

@@ -61,6 +61,10 @@ type Config struct {
 	// a command with sudo or so on. This is a configuration template where the `.Command` variable
 	// is replaced with the command to be run. Defaults to `{{.Command}}`.
 	CommandWrapper string `mapstructure:"command_wrapper"`
+	// Manual Mount Command that is executed to manually mount the
+	// root device and before the post mount commands. The device and
+	// mount path are provided by `{{.Device}}` and `{{.MountPath}}`.
+	ManualMountCommand string `mapstructure:"manual_mount_command" required:"false"`
 	// A series of commands to execute after attaching the root volume and before mounting the chroot.
 	// This is not required unless using `from_scratch`. If so, this should include any partitioning
 	// and filesystem creation commands. The path to the device is provided by `{{.Device}}`.
@@ -169,6 +173,7 @@ func (b *Builder) Prepare(raws ...interface{}) ([]string, []string, error) {
 				"command_wrapper",
 				"post_mount_commands",
 				"pre_mount_commands",
+				"manual_mount_command",
 				"mount_path",
 			},
 		},
@@ -611,11 +616,28 @@ func buildsteps(
 		&chroot.StepPreMountCommands{
 			Commands: config.PreMountCommands,
 		},
-		&StepMountDevice{
-			MountOptions:   config.MountOptions,
-			MountPartition: config.MountPartition,
-			MountPath:      config.MountPath,
-		},
+	)
+
+	if config.ManualMountCommand == "" {
+		addSteps(
+			&StepMountDevice{
+				MountOptions:   config.MountOptions,
+				MountPartition: config.MountPartition,
+				MountPath:      config.MountPath,
+			},
+		)
+	} else {
+		addSteps(
+			&StepManualMountCommand{
+				Command:        config.ManualMountCommand,
+				MountPartition: config.MountPartition,
+				MountPath:      config.MountPath,
+			},
+		)
+
+	}
+
+	addSteps(
 		&chroot.StepPostMountCommands{
 			Commands: config.PostMountCommands,
 		},

builder/azure/chroot/step_manual_mount_command.go

@@ -0,0 +1,110 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package chroot
+
+// mostly borrowed from ./builder/amazon/chroot/step_mount_device.go
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"path/filepath"
+	"runtime"
+
+	"github.com/hashicorp/packer-plugin-azure/builder/azure/common/log"
+
+	"github.com/hashicorp/packer-plugin-sdk/common"
+	"github.com/hashicorp/packer-plugin-sdk/multistep"
+	packersdk "github.com/hashicorp/packer-plugin-sdk/packer"
+	"github.com/hashicorp/packer-plugin-sdk/template/interpolate"
+)
+
+var _ multistep.Step = &StepManualMountCommand{}
+
+type StepManualMountCommand struct {
+	Command        string
+	MountPartition string
+	MountPath      string
+
+	mountPath string
+}
+
+func (s *StepManualMountCommand) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
+	ui := state.Get("ui").(packersdk.Ui)
+	device := state.Get("device").(string)
+	config := state.Get("config").(*Config)
+
+	ictx := config.ctx
+
+	ictx.Data = &struct{ Device string }{Device: filepath.Base(device)}
+	mountPath, err := interpolate.Render(s.MountPath, &ictx)
+
+	if err != nil {
+		err := fmt.Errorf("error preparing mount directory: %s", err)
+		state.Put("error", err)
+		ui.Error(err.Error())
+		return multistep.ActionHalt
+	}
+
+	mountPath, err = filepath.Abs(mountPath)
+	if err != nil {
+		err := fmt.Errorf("error preparing mount directory: %s", err)
+		state.Put("error", err)
+		ui.Error(err.Error())
+		return multistep.ActionHalt
+	}
+
+	log.Printf("Mount path: %s", mountPath)
+
+	var deviceMount string
+	switch runtime.GOOS {
+	case "freebsd":
+		deviceMount = fmt.Sprintf("%sp%s", device, s.MountPartition)
+	default:
+		deviceMount = fmt.Sprintf("%s%s", device, s.MountPartition)
+	}
+
+	state.Put("deviceMount", deviceMount)
+
+	ui.Say("Mounting the root device...")
+	stderr := new(bytes.Buffer)
+
+	log.Printf("[DEBUG] (step mount) mount command is %s", s.Command)
+	cmd := common.ShellCommand(fmt.Sprintf("%s %s", s.Command, mountPath))
+	cmd.Stderr = stderr
+	if err := cmd.Run(); err != nil {
+		err := fmt.Errorf(
+			"error mounting root volume: %s\nStderr: %s", err, stderr.String())
+		state.Put("error", err)
+		ui.Error(err.Error())
+		return multistep.ActionHalt
+	}
+
+	// Set the mount path so we remember to unmount it later
+	s.mountPath = mountPath
+	state.Put("mount_path", s.mountPath)
+	state.Put("mount_device_cleanup", s)
+
+	return multistep.ActionContinue
+}
+
+func (s *StepManualMountCommand) Cleanup(state multistep.StateBag) {
+	ui := state.Get("ui").(packersdk.Ui)
+	if err := s.CleanupFunc(state); err != nil {
+		ui.Error(err.Error())
+	}
+}
+
+func (s *StepManualMountCommand) CleanupFunc(state multistep.StateBag) error {
+	if s.mountPath == "" {
+		return nil
+	}
+
+	ui := state.Get("ui").(packersdk.Ui)
+
+	ui.Say("Skipping Unmounting the root device, it is manually unmounted via manual mount command script...")
+
+	s.mountPath = ""
+	return nil
+}