Use const for statebag key

builder/azure/chroot/const.go

@@ -0,0 +1,5 @@
+package chroot
+
+const (
+	stateBagKey_OSDiskResourceID = "os_disk_resource_id"
+)

builder/azure/chroot/step_attach_disk.go

@@ -20,7 +20,7 @@ type StepAttachDisk struct {
 func (s *StepAttachDisk) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
 	azcli := state.Get("azureclient").(client.AzureClientSet)
 	ui := state.Get("ui").(packer.Ui)
-	diskResourceID := state.Get("os_disk_resource_id").(string)
+	diskResourceID := state.Get(stateBagKey_OSDiskResourceID).(string)
 
 	ui.Say(fmt.Sprintf("Attaching disk '%s'", diskResourceID))
 
@@ -67,7 +67,7 @@ func (s *StepAttachDisk) CleanupFunc(state multistep.StateBag) error {
 	if s.attached {
 		azcli := state.Get("azureclient").(client.AzureClientSet)
 		ui := state.Get("ui").(packer.Ui)
-		diskResourceID := state.Get("os_disk_resource_id").(string)
+		diskResourceID := state.Get(stateBagKey_OSDiskResourceID).(string)
 
 		ui.Say(fmt.Sprintf("Detaching disk '%s'", diskResourceID))
 

builder/azure/chroot/step_attach_disk_test.go

@@ -78,7 +78,7 @@ func TestStepAttachDisk_Run(t *testing.T) {
 			state := new(multistep.BasicStateBag)
 			state.Put("azureclient", &client.AzureClientSetMock{})
 			state.Put("ui", ui)
-			state.Put("os_disk_resource_id", "/subscriptions/12345/resourceGroups/group1/providers/Microsoft.Compute/disks/disk1")
+			state.Put(stateBagKey_OSDiskResourceID, "/subscriptions/12345/resourceGroups/group1/providers/Microsoft.Compute/disks/disk1")
 
 			got := s.Run(context.TODO(), state)
 			if !reflect.DeepEqual(got, tt.want) {

builder/azure/chroot/step_create_image.go

@@ -28,7 +28,7 @@ type StepCreateImage struct {
 func (s *StepCreateImage) Run(ctx context.Context, state multistep.StateBag) multistep.StepAction {
 	azcli := state.Get("azureclient").(client.AzureClientSet)
 	ui := state.Get("ui").(packer.Ui)
-	diskResourceID := state.Get("os_disk_resource_id").(string)
+	diskResourceID := state.Get(stateBagKey_OSDiskResourceID).(string)
 
 	ui.Say(fmt.Sprintf("Creating image %s\n   using %s for os disk.",
 		s.ImageResourceID,