Merge pull request #10068 from hashicorp/b-destroy-edge

terraform: destroy edge must include resources through outputs

terraform/test-fixtures/transform-destroy-edge-module/child/main.tf

@@ -0,0 +1,5 @@
+resource "aws_instance" "b" {
+    value = "foo"
+}
+
+output "output" { value = "${aws_instance.b.value}" }

terraform/test-fixtures/transform-destroy-edge-module/main.tf

@@ -0,0 +1,7 @@
+resource "aws_instance" "a" {
+    value = "${module.child.output}"
+}
+
+module "child" {
+    source = "./child"
+}

terraform/transform_destroy_edge.go

@@ -116,8 +116,10 @@ func (t *DestroyEdgeTransformer) Transform(g *Graph) error {
 	// in the graph. BUT if resource A is just pure destroy, then only
 	// destroy A is in the graph, and create A is not.
 	steps := []GraphTransformer{
+		&OutputTransformer{Module: t.Module},
 		&AttachResourceConfigTransformer{Module: t.Module},
 		&AttachStateTransformer{State: t.State},
+		&ReferenceTransformer{},
 	}
 
 	// Go through all the nodes being destroyed and create a graph.
@@ -127,6 +129,7 @@ func (t *DestroyEdgeTransformer) Transform(g *Graph) error {
 	//   A, B (with no edges)
 	//
 	var tempG Graph
+	var tempDestroyed []dag.Vertex
 	for d, _ := range destroyers {
 		// d is what is being destroyed. We parse the resource address
 		// which it came from it is a panic if this fails.
@@ -140,6 +143,7 @@ func (t *DestroyEdgeTransformer) Transform(g *Graph) error {
 		// attach config and state transformers then ask for references.
 		node := &NodeAbstractResource{Addr: addr}
 		tempG.Add(node)
+		tempDestroyed = append(tempDestroyed, node)
 	}
 
 	// Run the graph transforms so we have the information we need to
@@ -150,14 +154,22 @@ func (t *DestroyEdgeTransformer) Transform(g *Graph) error {
 		}
 	}
 
-	// Create a reference map for easy lookup
-	refMap := NewReferenceMap(tempG.Vertices())
+	log.Printf("[TRACE] DestroyEdgeTransformer: reference graph: %s", tempG.String())
 
 	// Go through all the nodes in the graph and determine what they
 	// depend on.
-	for _, v := range tempG.Vertices() {
-		// Find all the references
-		refs, _ := refMap.References(v)
+	for _, v := range tempDestroyed {
+		// Find all ancestors of this to determine the edges we'll depend on
+		vs, err := tempG.Ancestors(v)
+		if err != nil {
+			return err
+		}
+
+		refs := make([]dag.Vertex, 0, vs.Len())
+		for _, raw := range vs.List() {
+			refs = append(refs, raw.(dag.Vertex))
+		}
+
 		log.Printf(
 			"[TRACE] DestroyEdgeTransformer: creation node %q references %v",
 			dag.VertexName(v), refs)

terraform/transform_destroy_edge_test.go

@@ -78,6 +78,24 @@ func TestDestroyEdgeTransformer_selfRef(t *testing.T) {
 	}
 }
 
+func TestDestroyEdgeTransformer_module(t *testing.T) {
+	g := Graph{Path: RootModulePath}
+	g.Add(&graphNodeDestroyerTest{AddrString: "module.child.aws_instance.b"})
+	g.Add(&graphNodeDestroyerTest{AddrString: "aws_instance.a"})
+	tf := &DestroyEdgeTransformer{
+		Module: testModule(t, "transform-destroy-edge-module"),
+	}
+	if err := tf.Transform(&g); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(testTransformDestroyEdgeModuleStr)
+	if actual != expected {
+		t.Fatalf("bad:\n\n%s", actual)
+	}
+}
+
 type graphNodeCreatorTest struct {
 	AddrString string
 }
@@ -125,6 +143,7 @@ test.B (destroy)
 const testTransformDestroyEdgeMultiStr = `
 test.A (destroy)
   test.B (destroy)
+  test.C (destroy)
 test.B (destroy)
   test.C (destroy)
 test.C (destroy)
@@ -133,3 +152,9 @@ test.C (destroy)
 const testTransformDestroyEdgeSelfRefStr = `
 test.A (destroy)
 `
+
+const testTransformDestroyEdgeModuleStr = `
+aws_instance.a (destroy)
+module.child.aws_instance.b (destroy)
+  aws_instance.a (destroy)
+`