Allow user to override chroot command.

builder/amazon/chroot/builder.go

@@ -30,6 +30,7 @@ type Config struct {
 	CopyFiles      []string   `mapstructure:"copy_files"`
 	DevicePath     string     `mapstructure:"device_path"`
 	MountCommand   string     `mapstructure:"mount_command"`
+	ChrootCommand  string     `mapstructure:"chroot_command"`
 	MountPath      string     `mapstructure:"mount_path"`
 	SourceAmi      string     `mapstructure:"source_ami"`
 	UnmountCommand string     `mapstructure:"unmount_command"`
@@ -82,6 +83,10 @@ func (b *Builder) Prepare(raws ...interface{}) error {
 		b.config.MountCommand = "mount"
 	}
 
+	if b.config.ChrootCommand == "" {
+		b.config.ChrootCommand = "chroot"
+	}
+
 	if b.config.MountPath == "" {
 		b.config.MountPath = "packer-amazon-chroot-volumes/{{.Device}}"
 	}
@@ -129,6 +134,7 @@ func (b *Builder) Prepare(raws ...interface{}) error {
 	templates := map[string]*string{
 		"device_path":     &b.config.DevicePath,
 		"mount_command":   &b.config.MountCommand,
+		"chroot_command":  &b.config.ChrootCommand,
 		"source_ami":      &b.config.SourceAmi,
 		"unmount_command": &b.config.UnmountCommand,
 	}

builder/amazon/chroot/communicator.go

@@ -14,15 +14,12 @@ import (
 // commands locally but within a chroot.
 type Communicator struct {
 	Chroot string
+    ChrootCommand string
 }
 
 func (c *Communicator) Start(cmd *packer.RemoteCmd) error {
-	chrootCmdPath, err := exec.LookPath("chroot")
-	if err != nil {
-		return err
-	}
 
-	localCmd := exec.Command(chrootCmdPath, c.Chroot, "/bin/sh", "-c", cmd.Command)
+	localCmd := exec.Command(c.ChrootCommand, c.Chroot, "/bin/sh", "-c", cmd.Command)
 	localCmd.Stdin = cmd.Stdin
 	localCmd.Stdout = cmd.Stdout
 	localCmd.Stderr = cmd.Stderr

builder/amazon/chroot/step_chroot_provision.go

@@ -14,11 +14,13 @@ type StepChrootProvision struct {
 func (s *StepChrootProvision) Run(state multistep.StateBag) multistep.StepAction {
 	hook := state.Get("hook").(packer.Hook)
 	mountPath := state.Get("mount_path").(string)
+	chrootCommand := state.Get("chroot_command").(string)
 	ui := state.Get("ui").(packer.Ui)
 
 	// Create our communicator
 	comm := &Communicator{
 		Chroot: mountPath,
+        ChrootCommand: chrootCommand,
 	}
 
 	// Provision