feature: add copy files step in chroot builder

builder/osc/chroot/builder.go

@@ -260,6 +260,7 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 			Commands: b.config.PostMountCommands,
 		},
 		&StepMountExtra{},
+		&StepCopyFiles{},
 	)
 
 	// Run!

builder/osc/chroot/step_copy_files.go

@@ -0,0 +1,91 @@
+package chroot
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"log"
+	"path/filepath"
+
+	"github.com/hashicorp/packer/helper/multistep"
+	"github.com/hashicorp/packer/packer"
+)
+
+// StepCopyFiles copies some files from the host into the chroot environment.
+//
+// Produces:
+//   copy_files_cleanup CleanupFunc - A function to clean up the copied files
+//   early.
+type StepCopyFiles struct {
+	files []string
+}
+
+func (s *StepCopyFiles) Run(_ context.Context, state multistep.StateBag) multistep.StepAction {
+	config := state.Get("config").(*Config)
+	mountPath := state.Get("mount_path").(string)
+	ui := state.Get("ui").(packer.Ui)
+	wrappedCommand := state.Get("wrappedCommand").(CommandWrapper)
+	stderr := new(bytes.Buffer)
+
+	s.files = make([]string, 0, len(config.CopyFiles))
+	if len(config.CopyFiles) > 0 {
+		ui.Say("Copying files from host to chroot...")
+		for _, path := range config.CopyFiles {
+			ui.Message(path)
+			chrootPath := filepath.Join(mountPath, path)
+			log.Printf("Copying '%s' to '%s'", path, chrootPath)
+
+			cmdText, err := wrappedCommand(fmt.Sprintf("cp --remove-destination %s %s", path, chrootPath))
+			if err != nil {
+				err := fmt.Errorf("Error building copy command: %s", err)
+				state.Put("error", err)
+				ui.Error(err.Error())
+				return multistep.ActionHalt
+			}
+
+			stderr.Reset()
+			cmd := ShellCommand(cmdText)
+			cmd.Stderr = stderr
+			if err := cmd.Run(); err != nil {
+				err := fmt.Errorf(
+					"Error copying file: %s\nnStderr: %s", err, stderr.String())
+				state.Put("error", err)
+				ui.Error(err.Error())
+				return multistep.ActionHalt
+			}
+
+			s.files = append(s.files, chrootPath)
+		}
+	}
+
+	state.Put("copy_files_cleanup", s)
+	return multistep.ActionContinue
+}
+
+func (s *StepCopyFiles) Cleanup(state multistep.StateBag) {
+	ui := state.Get("ui").(packer.Ui)
+	if err := s.CleanupFunc(state); err != nil {
+		ui.Error(err.Error())
+	}
+}
+
+func (s *StepCopyFiles) CleanupFunc(state multistep.StateBag) error {
+	wrappedCommand := state.Get("wrappedCommand").(CommandWrapper)
+	if s.files != nil {
+		for _, file := range s.files {
+			log.Printf("Removing: %s", file)
+			localCmdText, err := wrappedCommand(fmt.Sprintf("rm -f %s", file))
+			if err != nil {
+				return err
+			}
+
+			localCmd := ShellCommand(localCmdText)
+			if err := localCmd.Run(); err != nil {
+				return err
+			}
+		}
+	}
+
+	s.files = nil
+	return nil
+}