terraform: outputs connect properly

terraform/graph_config_node_module.go

@@ -27,7 +27,7 @@ func (n *GraphNodeConfigModule) DependableName() []string {
 	result := make([]string, 1, len(config.Outputs)+1)
 	result[0] = n.Name()
 	for _, o := range config.Outputs {
-		result = append(result, fmt.Sprintf("%s.%s", n.Name(), o.Name))
+		result = append(result, fmt.Sprintf("%s.output.%s", n.Name(), o.Name))
 	}
 
 	return result
@@ -116,6 +116,16 @@ func (n *graphNodeModuleExpanded) ConfigType() GraphNodeConfigType {
 	return GraphNodeConfigTypeModule
 }
 
+// GraphNodeDependable
+func (n *graphNodeModuleExpanded) DependableName() []string {
+	return n.Original.DependableName()
+}
+
+// GraphNodeDependent
+func (n *graphNodeModuleExpanded) DependentOn() []string {
+	return n.Original.DependentOn()
+}
+
 // GraphNodeDotter impl.
 func (n *graphNodeModuleExpanded) DotNode(name string, opts *GraphDotOpts) *dot.Node {
 	return dot.NewNode(name, map[string]string{

terraform/test-fixtures/transform-flatten/child/main.tf

@@ -3,3 +3,7 @@ variable "var" {}
 resource "aws_instance" "child" {
     value = "${var.var}"
 }
+
+output "output" {
+    value = "${aws_instance.child.value}"
+}

terraform/test-fixtures/transform-flatten/main.tf

@@ -6,3 +6,7 @@ module "child" {
 resource "aws_instance" "parent" {
     value = "foo"
 }
+
+resource "aws_instance" "parent-output" {
+    value = "${module.child.output}"
+}

terraform/transform_config.go

@@ -105,7 +105,7 @@ func (t *ConfigTransformer) Transform(g *Graph) error {
 func varNameForVar(raw config.InterpolatedVariable) string {
 	switch v := raw.(type) {
 	case *config.ModuleVariable:
-		return fmt.Sprintf("module.%s.%s", v.Name, v.Field)
+		return fmt.Sprintf("module.%s.output.%s", v.Name, v.Field)
 	case *config.ResourceVariable:
 		return v.ResourceId()
 	case *config.UserVariable:

terraform/transform_flatten.go

@@ -1,5 +1,9 @@
 package terraform
 
+import (
+	"github.com/hashicorp/terraform/dag"
+)
+
 // GraphNodeFlattenable must be implemented by nodes that can be flattened
 // into the graph.
 type GraphNodeFlattenable interface {
@@ -24,6 +28,17 @@ func (t *FlattenTransformer) Transform(g *Graph) error {
 			continue
 		}
 
+		// Get all the things that depend on this node. We'll re-connect
+		// dependents later. We have to copy these here since the UpEdges
+		// value will be deleted after the Remove below.
+		dependents := make([]dag.Vertex, 0, 5)
+		for _, v := range g.UpEdges(v).List() {
+			dependents = append(dependents, v)
+		}
+
+		// Remove the old node
+		g.Remove(v)
+
 		// Flatten the subgraph into this one. Keep any existing
 		// connections that existed.
 		for _, sv := range subgraph.Vertices() {
@@ -33,14 +48,18 @@ func (t *FlattenTransformer) Transform(g *Graph) error {
 			g.Connect(se)
 		}
 
-		// Remove the old node
-		g.Remove(v)
-
 		// Connect the dependencies for all the new nodes that we added.
 		// This will properly connect variables to their sources, for example.
 		for _, sv := range subgraph.Vertices() {
 			g.ConnectDependent(sv)
 		}
+
+		// Re-connect all the things that dependend on the graph
+		// we just flattened. This should connect them back into the
+		// correct nodes if their DependentOn() is setup correctly.
+		for _, v := range dependents {
+			g.ConnectDependent(v)
+		}
 	}
 
 	return nil

terraform/transform_flatten_test.go

@@ -37,8 +37,12 @@ func TestFlattenTransformer(t *testing.T) {
 
 const testTransformFlattenStr = `
 aws_instance.parent
+aws_instance.parent-output
+  module.child.output.output
 module.child.aws_instance.child
   module.child.var.var
+module.child.output.output
+  module.child.aws_instance.child
 module.child.var.var
   aws_instance.parent
 `