use aws helper method

builder/amazon/common/step_modify_ebs_instance.go

@@ -3,6 +3,7 @@ package common
 import (
 	"fmt"
 
+	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/service/ec2"
 	"github.com/mitchellh/multistep"
 	"github.com/mitchellh/packer/packer"
@@ -22,12 +23,12 @@ func (s *StepModifyEBSBackedInstance) Run(state multistep.StateBag) multistep.St
 		// As of February 2017, this applies to C3, C4, D2, I2, R3, and M4 (excluding m4.16xlarge)
 		ui.Say("Enabling Enhanced Networking (SR-IOV)...")
 		simple := "simple"
-		_, err_iov := ec2conn.ModifyInstanceAttribute(&ec2.ModifyInstanceAttributeInput{
+		_, err := ec2conn.ModifyInstanceAttribute(&ec2.ModifyInstanceAttributeInput{
 			InstanceId:      instance.InstanceId,
 			SriovNetSupport: &ec2.AttributeValue{Value: &simple},
 		})
-		if err_iov != nil {
+		if err != nil {
-			err := fmt.Errorf("Error enabling Enhanced Networking (SR-IOV) on %s: %s", *instance.InstanceId, err_iov)
+			err := fmt.Errorf("Error enabling Enhanced Networking (SR-IOV) on %s: %s", *instance.InstanceId, err)
 			state.Put("error", err)
 			ui.Error(err.Error())
 			return multistep.ActionHalt
@@ -36,13 +37,12 @@ func (s *StepModifyEBSBackedInstance) Run(state multistep.StateBag) multistep.St
 		// Set EnaSupport to true.
 		// As of February 2017, this applies to C5, I3, P2, R4, X1, and m4.16xlarge
 		ui.Say("Enabling Enhanced Networking (ENA)...")
-		truthy := true
+		_, err = ec2conn.ModifyInstanceAttribute(&ec2.ModifyInstanceAttributeInput{
-		_, err_ena := ec2conn.ModifyInstanceAttribute(&ec2.ModifyInstanceAttributeInput{
 			InstanceId: instance.InstanceId,
-			EnaSupport: &ec2.AttributeBooleanValue{Value: &truthy},
+			EnaSupport: &ec2.AttributeBooleanValue{Value: aws.Bool(true)},
 		})
-		if err_ena != nil {
+		if err != nil {
-			err := fmt.Errorf("Error enabling Enhanced Networking (ENA) on %s: %s", *instance.InstanceId, err_ena)
+			err := fmt.Errorf("Error enabling Enhanced Networking (ENA) on %s: %s", *instance.InstanceId, err)
 			state.Put("error", err)
 			ui.Error(err.Error())
 			return multistep.ActionHalt