Merge pull request #23435 from hashicorp/jbardin/cbd-deps

fix CreateBeforeDestroy de-duplication

terraform/testdata/transform-destroy-cbd-edge-multi/main.tf

@@ -0,0 +1,15 @@
+resource "test_object" "A" {
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+
+resource "test_object" "B" {
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+
+resource "test_object" "C" {
+  test_string = "${test_object.A.id}-${test_object.B.id}"
+}

terraform/transform_destroy_cbd.go

@@ -259,7 +259,9 @@ func (t *CBDEdgeTransformer) depMap(g *Graph, destroyMap map[string][]dag.Vertex
 	// Build the list of destroy nodes that each resource address should depend
 	// on. For example, when we find B, we map the address of B to A_d in the
 	// "depMap" variable below.
-	depMap := make(map[string][]dag.Vertex)
+
+	// Use a nested map to remove duplicate edges.
+	depMap := make(map[string]map[dag.Vertex]struct{})
 	for _, v := range g.Vertices() {
 		// We're looking for resources.
 		rn, ok := v.(GraphNodeResource)
@@ -294,12 +296,24 @@ func (t *CBDEdgeTransformer) depMap(g *Graph, destroyMap map[string][]dag.Vertex
 			// needs to depend on.
 			key := rn.ResourceAddr().String()
 
-			// we only need to record the same dns once
-			if _, ok := depMap[key]; !ok {
-				depMap[key] = append(depMap[key], dns...)
+			deps, ok := depMap[key]
+			if !ok {
+				deps = make(map[dag.Vertex]struct{})
 			}
+
+			for _, d := range dns {
+				deps[d] = struct{}{}
+			}
+			depMap[key] = deps
 		}
 	}
 
-	return depMap, nil
+	result := map[string][]dag.Vertex{}
+	for k, m := range depMap {
+		for v := range m {
+			result[k] = append(result[k], v)
+		}
+	}
+
+	return result, nil
 }

terraform/transform_destroy_cbd_test.go

@@ -95,6 +95,53 @@ test_object.B
 	}
 }
 
+func TestCBDEdgeTransformerMulti(t *testing.T) {
+	changes := &plans.Changes{
+		Resources: []*plans.ResourceInstanceChangeSrc{
+			{
+				Addr: mustResourceInstanceAddr("test_object.A"),
+				ChangeSrc: plans.ChangeSrc{
+					Action: plans.CreateThenDelete,
+				},
+			},
+			{
+				Addr: mustResourceInstanceAddr("test_object.B"),
+				ChangeSrc: plans.ChangeSrc{
+					Action: plans.CreateThenDelete,
+				},
+			},
+			{
+				Addr: mustResourceInstanceAddr("test_object.C"),
+				ChangeSrc: plans.ChangeSrc{
+					Action: plans.Update,
+				},
+			},
+		},
+	}
+
+	g := cbdTestGraph(t, "transform-destroy-cbd-edge-multi", changes)
+	g = filterInstances(g)
+
+	actual := strings.TrimSpace(g.String())
+	expected := regexp.MustCompile(strings.TrimSpace(`
+(?m)test_object.A
+test_object.A \(destroy deposed \w+\)
+  test_object.A
+  test_object.C
+test_object.B
+test_object.B \(destroy deposed \w+\)
+  test_object.B
+  test_object.C
+test_object.C
+  test_object.A
+  test_object.B
+`))
+
+	if !expected.MatchString(actual) {
+		t.Fatalf("wrong result\n\ngot:\n%s\n\nwant:\n%s", actual, expected)
+	}
+}
+
 func TestCBDEdgeTransformer_depNonCBDCount(t *testing.T) {
 	changes := &plans.Changes{
 		Resources: []*plans.ResourceInstanceChangeSrc{