terraform: introduce EvalApplyPre so that PreApply is called even for

destroy provisioners.

terraform/eval_apply.go

@@ -52,16 +52,6 @@ func (n *EvalApply) Eval(ctx EvalContext) (interface{}, error) {
 		*n.CreateNew = state.ID == "" && !diff.GetDestroy() || diff.RequiresNew()
 	}
 
-	{
-		// Call pre-apply hook
-		err := ctx.Hook(func(h Hook) (HookAction, error) {
-			return h.PreApply(n.Info, state, diff)
-		})
-		if err != nil {
-			return nil, err
-		}
-	}
-
 	// With the completed diff, apply!
 	log.Printf("[DEBUG] apply: %s: executing Apply", n.Info.Id)
 	state, err := provider.Apply(n.Info, state, diff)
@@ -104,6 +94,37 @@ func (n *EvalApply) Eval(ctx EvalContext) (interface{}, error) {
 	return nil, nil
 }
 
+// EvalApplyPre is an EvalNode implementation that does the pre-Apply work
+type EvalApplyPre struct {
+	Info  *InstanceInfo
+	State **InstanceState
+	Diff  **InstanceDiff
+}
+
+// TODO: test
+func (n *EvalApplyPre) Eval(ctx EvalContext) (interface{}, error) {
+	state := *n.State
+	diff := *n.Diff
+
+	// If the state is nil, make it non-nil
+	if state == nil {
+		state = new(InstanceState)
+	}
+	state.init()
+
+	{
+		// Call post-apply hook
+		err := ctx.Hook(func(h Hook) (HookAction, error) {
+			return h.PreApply(n.Info, state, diff)
+		})
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return nil, nil
+}
+
 // EvalApplyPost is an EvalNode implementation that does the post-Apply work
 type EvalApplyPost struct {
 	Info  *InstanceInfo

terraform/node_resource_apply.go

@@ -298,6 +298,12 @@ func (n *NodeApplyableResource) evalTreeManagedResource(
 				Name:   stateId,
 				Output: &state,
 			},
+			// Call pre-apply hook
+			&EvalApplyPre{
+				Info:  info,
+				State: &state,
+				Diff:  &diffApply,
+			},
 			&EvalApply{
 				Info:      info,
 				State:     &state,

terraform/node_resource_destroy.go

@@ -172,6 +172,13 @@ func (n *NodeDestroyResource) EvalTree() EvalNode {
 					State: &state,
 				},
 
+				// Call pre-apply hook
+				&EvalApplyPre{
+					Info:  info,
+					State: &state,
+					Diff:  &diffApply,
+				},
+
 				// Run destroy provisioners if not tainted
 				&EvalIf{
 					If: func(ctx EvalContext) (bool, error) {

terraform/terraform_test.go

@@ -179,6 +179,10 @@ func (h *HookRecordApplyOrder) PreApply(
 	info *InstanceInfo,
 	s *InstanceState,
 	d *InstanceDiff) (HookAction, error) {
+	if d.Empty() {
+		return HookActionContinue, nil
+	}
+
 	if h.Active {
 		h.l.Lock()
 		defer h.l.Unlock()

terraform/transform_deposed.go

@@ -127,6 +127,12 @@ func (n *graphNodeDeposedResource) EvalTree() EvalNode {
 					State:  &state,
 					Output: &diff,
 				},
+				// Call pre-apply hook
+				&EvalApplyPre{
+					Info:  info,
+					State: &state,
+					Diff:  &diff,
+				},
 				&EvalApply{
 					Info:     info,
 					State:    &state,

terraform/transform_orphan.go

@@ -321,6 +321,11 @@ func (n *graphNodeOrphanResource) managedResourceEvalNodes(info *InstanceInfo) [
 					Name:   n.ResourceKey.String(),
 					Output: &state,
 				},
+				&EvalApplyPre{
+					Info:  info,
+					State: &state,
+					Diff:  &diff,
+				},
 				&EvalApply{
 					Info:     info,
 					State:    &state,

terraform/transform_resource.go

@@ -500,6 +500,11 @@ func (n *graphNodeExpandedResource) managedResourceEvalNodes(resource *Resource,
 					Name:   n.stateId(),
 					Output: &state,
 				},
+				&EvalApplyPre{
+					Info:  info,
+					State: &state,
+					Diff:  &diffApply,
+				},
 				&EvalApply{
 					Info:      info,
 					State:     &state,