Merge pull request #23399 from hashicorp/jbardin/cbd-cycle

CBD GraphNodeCreators cannot depend on GraphNodeDestroyers

terraform/context_apply_test.go

@@ -11099,3 +11099,121 @@ func TestContext2Apply_taintedDestroyFailure(t *testing.T) {
 		t.Fatalf("unexpected attrs for c: %q\n", c.Current.AttrsJSON)
 	}
 }
+
+func TestContext2Apply_cbdCycle(t *testing.T) {
+	m, snap := testModuleWithSnapshot(t, "apply-cbd-cycle")
+	p := testProvider("test")
+	p.ApplyFn = testApplyFn
+	p.DiffFn = testDiffFn
+
+	state := states.NewState()
+	root := state.EnsureModule(addrs.RootModuleInstance)
+	root.SetResourceInstanceCurrent(
+		addrs.Resource{
+			Mode: addrs.ManagedResourceMode,
+			Type: "test_instance",
+			Name: "a",
+		}.Instance(addrs.NoKey),
+		&states.ResourceInstanceObjectSrc{
+			Status:    states.ObjectReady,
+			AttrsJSON: []byte(`{"id":"a","require_new":"old","foo":"b"}`),
+			Dependencies: []addrs.AbsResource{
+				addrs.AbsResource{
+					Resource: addrs.Resource{
+						Mode: addrs.ManagedResourceMode,
+						Type: "test_instance",
+						Name: "b",
+					},
+					Module: addrs.RootModuleInstance,
+				},
+				addrs.AbsResource{
+					Resource: addrs.Resource{
+						Mode: addrs.ManagedResourceMode,
+						Type: "test_instance",
+						Name: "c",
+					},
+					Module: addrs.RootModuleInstance,
+				},
+			},
+		},
+		addrs.ProviderConfig{
+			Type: "test",
+		}.Absolute(addrs.RootModuleInstance),
+	)
+	root.SetResourceInstanceCurrent(
+		addrs.Resource{
+			Mode: addrs.ManagedResourceMode,
+			Type: "test_instance",
+			Name: "b",
+		}.Instance(addrs.NoKey),
+		&states.ResourceInstanceObjectSrc{
+			Status:    states.ObjectReady,
+			AttrsJSON: []byte(`{"id":"b","require_new":"old","foo":"c"}`),
+			Dependencies: []addrs.AbsResource{
+				addrs.AbsResource{
+					Resource: addrs.Resource{
+						Mode: addrs.ManagedResourceMode,
+						Type: "test_instance",
+						Name: "c",
+					},
+					Module: addrs.RootModuleInstance,
+				},
+			},
+		},
+		addrs.ProviderConfig{
+			Type: "test",
+		}.Absolute(addrs.RootModuleInstance),
+	)
+	root.SetResourceInstanceCurrent(
+		addrs.Resource{
+			Mode: addrs.ManagedResourceMode,
+			Type: "test_instance",
+			Name: "c",
+		}.Instance(addrs.NoKey),
+		&states.ResourceInstanceObjectSrc{
+			Status:    states.ObjectReady,
+			AttrsJSON: []byte(`{"id":"c","require_new":"old"}`),
+		},
+		addrs.ProviderConfig{
+			Type: "test",
+		}.Absolute(addrs.RootModuleInstance),
+	)
+
+	providerResolver := providers.ResolverFixed(
+		map[string]providers.Factory{
+			"test": testProviderFuncFixed(p),
+		},
+	)
+
+	hook := &testHook{}
+	ctx := testContext2(t, &ContextOpts{
+		Config:           m,
+		ProviderResolver: providerResolver,
+		State:            state,
+		Hooks:            []Hook{hook},
+	})
+
+	plan, diags := ctx.Plan()
+	diags.HasErrors()
+	if diags.HasErrors() {
+		t.Fatalf("diags: %s", diags.Err())
+	}
+
+	// We'll marshal and unmarshal the plan here, to ensure that we have
+	// a clean new context as would be created if we separately ran
+	// terraform plan -out=tfplan && terraform apply tfplan
+	ctxOpts, err := contextOptsForPlanViaFile(snap, state, plan)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ctxOpts.ProviderResolver = providerResolver
+	ctx, diags = NewContext(ctxOpts)
+	if diags.HasErrors() {
+		t.Fatalf("failed to create context for plan: %s", diags.Err())
+	}
+
+	_, diags = ctx.Apply()
+	if diags.HasErrors() {
+		t.Fatalf("diags: %s", diags.Err())
+	}
+}

terraform/context_refresh_test.go

@@ -1978,6 +1978,17 @@ func TestRefresh_updateDependencies(t *testing.T) {
 		&states.ResourceInstanceObjectSrc{
 			Status:    states.ObjectReady,
 			AttrsJSON: []byte(`{"id":"foo"}`),
+			Dependencies: []addrs.AbsResource{
+				// Existing dependencies should not be removed during refresh
+				{
+					Module: addrs.RootModuleInstance,
+					Resource: addrs.Resource{
+						Mode: addrs.ManagedResourceMode,
+						Type: "aws_instance",
+						Name: "baz",
+					},
+				},
+			},
 		},
 		addrs.ProviderConfig{
 			Type: "aws",
@@ -1992,17 +2003,6 @@ func TestRefresh_updateDependencies(t *testing.T) {
 		&states.ResourceInstanceObjectSrc{
 			Status:    states.ObjectReady,
 			AttrsJSON: []byte(`{"id":"bar","foo":"foo"}`),
-			Dependencies: []addrs.AbsResource{
-				// Existing dependencies should not be removed during refresh
-				{
-					Module: addrs.RootModuleInstance,
-					Resource: addrs.Resource{
-						Mode: addrs.ManagedResourceMode,
-						Type: "aws_instance",
-						Name: "baz",
-					},
-				},
-			},
 		},
 		addrs.ProviderConfig{
 			Type: "aws",
@@ -2045,11 +2045,13 @@ aws_instance.bar:
   foo = foo
 
   Dependencies:
-    aws_instance.baz
     aws_instance.foo
 aws_instance.foo:
   ID = foo
   provider = provider.aws
+
+  Dependencies:
+    aws_instance.baz
 `)
 
 	checkStateString(t, result, expect)

terraform/eval_state.go

@@ -508,8 +508,13 @@ func (n *EvalRefreshDependencies) Eval(ctx EvalContext) (interface{}, error) {
 		depMap[d.String()] = d
 	}
 
-	for _, d := range state.Dependencies {
-		depMap[d.String()] = d
+	// We have already dependencies in state, so we need to trust those for
+	// refresh. We can't write out new dependencies until apply time in case
+	// the configuration has been changed in a manner the conflicts with the
+	// stored dependencies.
+	if len(state.Dependencies) > 0 {
+		*n.Dependencies = state.Dependencies
+		return nil, nil
 	}
 
 	deps := make([]addrs.AbsResource, 0, len(depMap))

terraform/testdata/apply-cbd-cycle/main.tf

@@ -0,0 +1,19 @@
+resource "test_instance" "a" {
+  foo = test_instance.b.id
+  require_new = "changed"
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+
+resource "test_instance" "b" {
+  foo = test_instance.c.id
+  require_new = "changed"
+}
+
+
+resource "test_instance" "c" {
+  require_new = "changed"
+}
+

terraform/transform_destroy_cbd.go

@@ -160,14 +160,11 @@ func (t *CBDEdgeTransformer) Transform(g *Graph) error {
 			continue
 		}
 
-		// Find the destroy edge. There should only be one.
+		// Find the resource edges
 		for _, e := range g.EdgesTo(v) {
-			// Not a destroy edge, ignore it
-			de, ok := e.(*DestroyEdge)
-			if !ok {
-				continue
-			}
-
+			switch de := e.(type) {
+			case *DestroyEdge:
+				// we need to invert the destroy edge from the create node
 				log.Printf("[TRACE] CBDEdgeTransformer: inverting edge: %s => %s",
 					dag.VertexName(de.Source()), dag.VertexName(de.Target()))
 
@@ -176,7 +173,14 @@ func (t *CBDEdgeTransformer) Transform(g *Graph) error {
 				applyNode := de.Source()
 				destroyNode := de.Target()
 				g.Connect(&DestroyEdge{S: destroyNode, T: applyNode})
-			break
+			default:
+				// We cannot have any direct dependencies from creators when
+				// the node is CBD without inducing a cycle.
+				if _, ok := e.Source().(GraphNodeCreator); ok {
+					log.Printf("[TRACE] CBDEdgeTransformer: removing non DestroyEdge to CBD destroy node: %s => %s", dag.VertexName(e.Source()), dag.VertexName(e.Target()))
+					g.RemoveEdge(e)
+				}
+			}
 		}
 
 		// If the address has an index, we strip that. Our depMap creation
@@ -289,9 +293,13 @@ func (t *CBDEdgeTransformer) depMap(g *Graph, destroyMap map[string][]dag.Vertex
 			// Keep track of the destroy nodes that this address
 			// 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...)
 			}
 		}
+	}
 
 	return depMap, nil
 }

terraform/transform_destroy_edge.go

@@ -122,6 +122,12 @@ func (t *DestroyEdgeTransformer) Transform(g *Graph) error {
 
 		for _, resAddr := range ri.StateDependencies() {
 			for _, desDep := range destroyersByResource[resAddr.String()] {
+				// TODO: don't connect this if c is CreateBeforeDestroy.
+				//       This will require getting the actual change action at
+				//       this point, since the lifecycle may have been forced
+				//       by a dependent. This should prevent needing to prune
+				//       the edge back out in CBDEdgeTransformer, and allow
+				//       non-CBD nodes to depend on CBD destroys directly.
 				log.Printf("[TRACE] DestroyEdgeTransformer: %s has stored dependency of %s\n", dag.VertexName(c), dag.VertexName(desDep))
 				g.Connect(dag.BasicEdge(c, desDep))