terraform: destroy node should not create

terraform/eval_diff.go

@@ -238,6 +238,38 @@ func (n *EvalDiffTainted) Eval(ctx EvalContext) (interface{}, error) {
 	return nil, nil
 }
 
+// EvalFilterDiff is an EvalNode implementation that filters the diff
+// according to some filter.
+type EvalFilterDiff struct {
+	// Input and output
+	Diff   **InstanceDiff
+	Output **InstanceDiff
+
+	// Destroy, if true, will only include a destroy diff if it is set.
+	Destroy bool
+}
+
+func (n *EvalFilterDiff) Eval(ctx EvalContext) (interface{}, error) {
+	if *n.Diff == nil {
+		return nil, nil
+	}
+
+	input := *n.Diff
+	result := new(InstanceDiff)
+
+	if n.Destroy {
+		if input.Destroy || input.RequiresNew() {
+			result.Destroy = true
+		}
+	}
+
+	if n.Output != nil {
+		*n.Output = result
+	}
+
+	return nil, nil
+}
+
 // EvalReadDiff is an EvalNode implementation that writes the diff to
 // the full diff.
 type EvalReadDiff struct {
@@ -275,7 +307,10 @@ func (n *EvalWriteDiff) Eval(ctx EvalContext) (interface{}, error) {
 	diff, lock := ctx.Diff()
 
 	// The diff to write, if its empty it should write nil
-	diffVal := *n.Diff
+	var diffVal *InstanceDiff
+	if n.Diff != nil {
+		diffVal = *n.Diff
+	}
 	if diffVal.Empty() {
 		diffVal = nil
 	}

terraform/eval_diff_test.go

@@ -0,0 +1,78 @@
+package terraform
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestEvalFilterDiff(t *testing.T) {
+	ctx := new(MockEvalContext)
+
+	cases := []struct {
+		Node   *EvalFilterDiff
+		Input  *InstanceDiff
+		Output *InstanceDiff
+	}{
+		// With no settings, it returns an empty diff
+		{
+			&EvalFilterDiff{},
+			&InstanceDiff{Destroy: true},
+			&InstanceDiff{},
+		},
+
+		// Destroy
+		{
+			&EvalFilterDiff{Destroy: true},
+			&InstanceDiff{Destroy: false},
+			&InstanceDiff{Destroy: false},
+		},
+		{
+			&EvalFilterDiff{Destroy: true},
+			&InstanceDiff{Destroy: true},
+			&InstanceDiff{Destroy: true},
+		},
+		{
+			&EvalFilterDiff{Destroy: true},
+			&InstanceDiff{
+				Destroy: true,
+				Attributes: map[string]*ResourceAttrDiff{
+					"foo": &ResourceAttrDiff{},
+				},
+			},
+			&InstanceDiff{Destroy: true},
+		},
+		{
+			&EvalFilterDiff{Destroy: true},
+			&InstanceDiff{
+				Attributes: map[string]*ResourceAttrDiff{
+					"foo": &ResourceAttrDiff{
+						RequiresNew: true,
+					},
+				},
+			},
+			&InstanceDiff{Destroy: true},
+		},
+		{
+			&EvalFilterDiff{Destroy: true},
+			&InstanceDiff{
+				Attributes: map[string]*ResourceAttrDiff{
+					"foo": &ResourceAttrDiff{},
+				},
+			},
+			&InstanceDiff{Destroy: false},
+		},
+	}
+
+	for i, tc := range cases {
+		var output *InstanceDiff
+		tc.Node.Diff = &tc.Input
+		tc.Node.Output = &output
+		if _, err := tc.Node.Eval(ctx); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+
+		if !reflect.DeepEqual(output, tc.Output) {
+			t.Fatalf("bad: %d\n\n%#v", i, output)
+		}
+	}
+}

terraform/eval_state.go

@@ -43,10 +43,9 @@ func (n *EvalReadState) Eval(ctx EvalContext) (interface{}, error) {
 		if idx < 0 {
 			idx = len(rs.Tainted) - 1
 		}
-
+		if idx >= 0 && idx < len(rs.Tainted) {
-		if idx < len(rs.Tainted) {
 			// Return the proper tainted resource
-			result = rs.Tainted[n.TaintedIndex]
+			result = rs.Tainted[idx]
 		}
 	}
 
@@ -58,6 +57,25 @@ func (n *EvalReadState) Eval(ctx EvalContext) (interface{}, error) {
 	return result, nil
 }
 
+// EvalRequireState is an EvalNode implementation that early exits
+// if the state doesn't have an ID.
+type EvalRequireState struct {
+	State **InstanceState
+}
+
+func (n *EvalRequireState) Eval(ctx EvalContext) (interface{}, error) {
+	if n.State == nil {
+		return nil, EvalEarlyExitError{}
+	}
+
+	state := *n.State
+	if state == nil || state.ID == "" {
+		return nil, EvalEarlyExitError{}
+	}
+
+	return nil, nil
+}
+
 // EvalUpdateStateHook is an EvalNode implementation that calls the
 // PostStateUpdate hook with the current state.
 type EvalUpdateStateHook struct{}

terraform/eval_state_test.go

@@ -5,6 +5,47 @@ import (
 	"testing"
 )
 
+func TestEvalRequireState(t *testing.T) {
+	ctx := new(MockEvalContext)
+
+	cases := []struct {
+		State *InstanceState
+		Exit  bool
+	}{
+		{
+			nil,
+			true,
+		},
+		{
+			&InstanceState{},
+			true,
+		},
+		{
+			&InstanceState{ID: "foo"},
+			false,
+		},
+	}
+
+	var exitVal EvalEarlyExitError
+	for _, tc := range cases {
+		node := &EvalRequireState{State: &tc.State}
+		_, err := node.Eval(ctx)
+		if tc.Exit {
+			if err != exitVal {
+				t.Fatalf("should've exited: %#v", tc.State)
+			}
+
+			continue
+		}
+		if !tc.Exit && err != nil {
+			t.Fatalf("shouldn't exit: %#v", tc.State)
+		}
+		if err != nil {
+			t.Fatalf("err: %s", err)
+		}
+	}
+}
+
 func TestEvalUpdateStateHook(t *testing.T) {
 	mockHook := new(MockHook)
 

terraform/transform_resource.go

@@ -386,6 +386,15 @@ func (n *graphNodeExpandedResource) EvalTree() EvalNode {
 						Name: n.stateId(),
 					},
 				},
+
+				// We clear the diff out here so that future nodes
+				// don't see a diff that is already complete. There
+				// is no longer a diff!
+				&EvalWriteDiff{
+					Name: n.stateId(),
+					Diff: nil,
+				},
+
 				&EvalWriteState{
 					Name:                n.stateId(),
 					ResourceType:        n.Resource.Type,
@@ -455,6 +464,13 @@ func (n *graphNodeExpandedResourceDestroy) EvalTree() EvalNode {
 					Diff: &diffApply,
 				},
 
+				// Filter the diff so we only get the destroy
+				&EvalFilterDiff{
+					Diff:    &diffApply,
+					Output:  &diffApply,
+					Destroy: true,
+				},
+
 				// If we're not destroying, then compare diffs
 				&EvalIf{
 					If: func(ctx EvalContext) (bool, error) {
@@ -477,6 +493,9 @@ func (n *graphNodeExpandedResourceDestroy) EvalTree() EvalNode {
 					Tainted:      n.Resource.Lifecycle.CreateBeforeDestroy,
 					TaintedIndex: -1,
 				},
+				&EvalRequireState{
+					State: &state,
+				},
 				&EvalApply{
 					Info:     info,
 					State:    &state,