terraform: turn resource expand into graph

terraform/context.go

@@ -1259,35 +1259,14 @@ func (c *walkContext) genericWalkResource(
 	rc.interpolate(c, rn.Resource)
 
 	// Expand the node to the actual resources
-	ns, err := rn.Expand()
+	g, err := rn.Expand()
 	if err != nil {
 		return err
 	}
 
-	// Go through all the nouns and run them in parallel, collecting
-	// any errors.
-	var l sync.Mutex
-	var wg sync.WaitGroup
-	errs := make([]error, 0, len(ns))
-	for _, n := range ns {
-		wg.Add(1)
-
-		go func(n *depgraph.Noun) {
-			defer wg.Done()
-			if err := fn(n); err != nil {
-				l.Lock()
-				defer l.Unlock()
-				errs = append(errs, err)
-			}
-		}(n)
-	}
-
-	// Wait for the subgraph
-	wg.Wait()
-
-	// If there are errors, then we should return them
-	if len(errs) > 0 {
-		return &multierror.Error{Errors: errs}
+	// Walk the graph with our function
+	if err := g.Walk(fn); err != nil {
+		return err
 	}
 
 	return nil

terraform/graph.go

@@ -1016,12 +1016,7 @@ func graphAddConfigProviderConfigs(g *depgraph.Graph, c *config.Config) {
 func graphAddRoot(g *depgraph.Graph) {
 	root := &depgraph.Noun{Name: GraphRootNode}
 	for _, n := range g.Nouns {
-		switch m := n.Meta.(type) {
-		case *GraphNodeResource:
-			// If the resource is part of a group, we don't need to make a dep
-			if m.Index != -1 {
-				continue
-			}
+		switch n.Meta.(type) {
 		case *GraphNodeResourceProvider:
 			// ResourceProviders don't need to be in the root deps because
 			// they're always pointed to by some resource.
@@ -1554,6 +1549,27 @@ func graphMapResourceProvisioners(g *depgraph.Graph,
 	return nil
 }
 
+// grpahRemoveInvalidDeps goes through the graph and removes dependencies
+// that no longer exist.
+func graphRemoveInvalidDeps(g *depgraph.Graph) {
+	check := make(map[*depgraph.Noun]struct{})
+	for _, n := range g.Nouns {
+		check[n] = struct{}{}
+	}
+	for _, n := range g.Nouns {
+		deps := n.Deps
+		num := len(deps)
+		for i := 0; i < num; i++ {
+			if _, ok := check[deps[i].Target]; !ok {
+				deps[i], deps[num-1] = deps[num-1], nil
+				i--
+				num--
+			}
+		}
+		n.Deps = deps[:num]
+	}
+}
+
 // MergeConfig merges all the configurations in the proper order
 // to result in the final configuration to use to configure this
 // provider.
@@ -1599,7 +1615,7 @@ func (p *graphSharedProvider) MergeConfig(
 }
 
 // Expand will expand this node into a subgraph if Expand is set.
-func (n *GraphNodeResource) Expand() ([]*depgraph.Noun, error) {
+func (n *GraphNodeResource) Expand() (*depgraph.Graph, error) {
 	// Expand the count out, which should be interpolated at this point.
 	count, err := n.Config.Count()
 	if err != nil {
@@ -1627,7 +1643,7 @@ func (n *GraphNodeResource) Expand() ([]*depgraph.Noun, error) {
 	// If we're just expanding the apply, then filter those out and
 	// return them now.
 	if n.ExpandMode == ResourceExpandApply {
-		return n.finalizeNouns(g, false), nil
+		return n.finalizeGraph(g, false)
 	}
 
 	if n.State != nil {
@@ -1637,7 +1653,7 @@ func (n *GraphNodeResource) Expand() ([]*depgraph.Noun, error) {
 		graphAddTainted(g, n.State)
 	}
 
-	return n.finalizeNouns(g, true), nil
+	return n.finalizeGraph(g, true)
 }
 
 // expand expands this resource and adds the resources to the graph. It
@@ -1759,8 +1775,8 @@ func (n *GraphNodeResource) copyResource(id string) *Resource {
 	return &resource
 }
 
-func (n *GraphNodeResource) finalizeNouns(
-	g *depgraph.Graph, destroy bool) []*depgraph.Noun {
+func (n *GraphNodeResource) finalizeGraph(
+	g *depgraph.Graph, destroy bool) (*depgraph.Graph, error) {
 	result := make([]*depgraph.Noun, 0, len(g.Nouns))
 	for _, n := range g.Nouns {
 		rn, ok := n.Meta.(*GraphNodeResource)
@@ -1802,7 +1818,22 @@ func (n *GraphNodeResource) finalizeNouns(
 			result = append(result, n)
 		}
 	}
-	return result
+
+	// Set the nouns to be only those we care about
+	g.Nouns = result
+
+	// Remove the dependencies that don't exist
+	graphRemoveInvalidDeps(g)
+
+	// Build the root so that we have a single valid root
+	graphAddRoot(g)
+
+	// Validate
+	if err := g.Validate(); err != nil {
+		return nil, err
+	}
+
+	return g, nil
 }
 
 // matchingPrefixes takes a resource type and a set of resource

terraform/graph_test.go

@@ -980,6 +980,98 @@ func TestGraph_orphanDependenciesModules(t *testing.T) {
 	}
 }
 
+func TestGraphNodeResourceExpand(t *testing.T) {
+	m := testModule(t, "graph-resource-expand")
+
+	g, err := Graph(&GraphOpts{Module: m})
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Get the resource we care about expanding
+	n := g.Noun("aws_instance.web")
+	if n == nil {
+		t.Fatal("could not find")
+	}
+	rn := n.Meta.(*GraphNodeResource)
+
+	g, err = rn.Expand()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(testTerraformGraphResourceExpandStr)
+	if actual != expected {
+		t.Fatalf("bad:\n\nactual:\n%s\n\nexpected:\n%s", actual, expected)
+	}
+}
+
+/*
+func TestGraphNodeResourceExpand_tainted(t *testing.T) {
+	m := testModule(t, "graph-resource-expand")
+	state := &State{
+		Modules: []*ModuleState{
+			&ModuleState{
+				Path: rootModulePath,
+
+				Resources: map[string]*ResourceState{
+					"aws_instance.web.0": &ResourceState{
+						Type: "aws_instance",
+						Tainted: []*InstanceState{
+							&InstanceState{
+								ID: "bar",
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	g, err := Graph(&GraphOpts{Module: m, State: state})
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	// Get the resource we care about expanding
+	n := g.Noun("aws_instance.web")
+	if n == nil {
+		t.Fatal("could not find")
+	}
+	rn := n.Meta.(*GraphNodeResource)
+
+	g, err = rn.Expand()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(testTerraformGraphResourceExpandTaintStr)
+	if actual != expected {
+		t.Fatalf("bad:\n\nactual:\n%s\n\nexpected:\n%s", actual, expected)
+	}
+
+	// Check the destruction noun
+	n = g.Noun("aws_instance.web (destroy)")
+	if n == nil {
+		t.Fatal("could not find")
+	}
+	rn = n.Meta.(*GraphNodeResource)
+
+	g, err = rn.Expand()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual = strings.TrimSpace(g.String())
+	expected = strings.TrimSpace(testTerraformGraphResourceExpandStr)
+	if actual != expected {
+		t.Fatalf("bad:\n\nactual:\n%s\n\nexpected:\n%s", actual, expected)
+	}
+}
+*/
+
 const testTerraformGraphStr = `
 root: root
 aws_instance.web
@@ -1277,3 +1369,25 @@ root
   root -> aws_security_group.firewall
   root -> module.consul
 `
+
+const testTerraformGraphResourceExpandStr = `
+root: root
+aws_instance.web.0
+aws_instance.web.1
+aws_instance.web.2
+root
+  root -> aws_instance.web.0
+  root -> aws_instance.web.1
+  root -> aws_instance.web.2
+`
+
+const testTerraformGraphResourceExpandTaintStr = `
+root: root
+aws_instance.web.0
+aws_instance.web.1
+aws_instance.web.2
+root
+  root -> aws_instance.web.0
+  root -> aws_instance.web.1
+  root -> aws_instance.web.2
+`

terraform/test-fixtures/graph-resource-expand/main.tf

@@ -0,0 +1,3 @@
+resource "aws_instance" "web" {
+    count = 3
+}