builder/amazon-chroot: add root_volume_size to resize chroot root volume

builder/amazon/chroot/builder.go

@@ -34,6 +34,7 @@ type Config struct {
 	DevicePath     string     `mapstructure:"device_path"`
 	MountPath      string     `mapstructure:"mount_path"`
 	SourceAmi      string     `mapstructure:"source_ami"`
+	RootVolumeSize int64      `mapstructure:"root_volume_size"`
 
 	ctx interpolate.Context
 }
@@ -159,7 +160,9 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 		&StepCheckRootDevice{},
 		&StepFlock{},
 		&StepPrepareDevice{},
-		&StepCreateVolume{},
+		&StepCreateVolume{
+			RootVolumeSize: b.config.RootVolumeSize,
+		},
 		&StepAttachVolume{},
 		&StepEarlyUnflock{},
 		&StepMountDevice{},
@@ -172,7 +175,9 @@ func (b *Builder) Run(ui packer.Ui, hook packer.Hook, cache packer.Cache) (packe
 			ForceDeregister: b.config.AMIForceDeregister,
 			AMIName:         b.config.AMIName,
 		},
-		&StepRegisterAMI{},
+		&StepRegisterAMI{
+			RootVolumeSize: b.config.RootVolumeSize,
+		},
 		&awscommon.StepAMIRegionCopy{
 			AccessConfig: &b.config.AccessConfig,
 			Regions:      b.config.AMIRegions,

builder/amazon/chroot/step_create_volume.go

@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"log"
 
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/awsutil"
 	"github.com/aws/aws-sdk-go/service/ec2"
 	"github.com/mitchellh/multistep"
 	awscommon "github.com/mitchellh/packer/builder/amazon/common"
@@ -17,6 +19,7 @@ import (
 //   volume_id string - The ID of the created volume
 type StepCreateVolume struct {
 	volumeId       string
+	RootVolumeSize int64
 }
 
 func (s *StepCreateVolume) Run(state multistep.StateBag) multistep.StepAction {
@@ -43,14 +46,18 @@ func (s *StepCreateVolume) Run(state multistep.StateBag) multistep.StepAction {
 	}
 
 	ui.Say("Creating the root volume...")
+	vs := *rootDevice.EBS.VolumeSize
+	if s.RootVolumeSize > *rootDevice.EBS.VolumeSize {
+		vs = s.RootVolumeSize
+	}
 	createVolume := &ec2.CreateVolumeInput{
 		AvailabilityZone: instance.Placement.AvailabilityZone,
-		Size:             rootDevice.EBS.VolumeSize,
+		Size:             aws.Long(vs),
 		SnapshotID:       rootDevice.EBS.SnapshotID,
 		VolumeType:       rootDevice.EBS.VolumeType,
 		IOPS:             rootDevice.EBS.IOPS,
 	}
-	log.Printf("Create args: %#v", createVolume)
+	log.Printf("Create args: %s", awsutil.StringValue(createVolume))
 
 	createVolumeResp, err := ec2conn.CreateVolume(createVolume)
 	if err != nil {

builder/amazon/chroot/step_register_ami.go

@@ -11,7 +11,9 @@ import (
 )
 
 // StepRegisterAMI creates the AMI.
-type StepRegisterAMI struct{}
+type StepRegisterAMI struct {
+	RootVolumeSize int64
+}
 
 func (s *StepRegisterAMI) Run(state multistep.StateBag) multistep.StepAction {
 	config := state.Get("config").(*Config)
@@ -30,6 +32,10 @@ func (s *StepRegisterAMI) Run(state multistep.StateBag) multistep.StepAction {
 			} else {
 				newDevice.EBS = &ec2.EBSBlockDevice{SnapshotID: aws.String(snapshotId)}
 			}
+
+			if s.RootVolumeSize > *newDevice.EBS.VolumeSize {
+				newDevice.EBS.VolumeSize = aws.Long(s.RootVolumeSize)
+			}
 		}
 
 		// assume working from a snapshot, so we unset the Encrypted field if set,