terraform: expand modules in our builder

terraform/graph_builder.go

@@ -74,6 +74,13 @@ func (b *BuiltinGraphBuilder) Steps() []GraphTransformer {
 		&MissingProviderTransformer{Providers: b.Providers},
 		&ProviderTransformer{},
 		&PruneProviderTransformer{},
+		&VertexTransformer{
+			Transforms: []GraphVertexTransformer{
+				&ExpandTransform{
+					Builder: b,
+				},
+			},
+		},
 		&RootTransformer{},
 	}
 }

terraform/graph_builder_test.go

@@ -29,6 +29,24 @@ func TestBuiltinGraphBuilder(t *testing.T) {
 	}
 }
 
+// This test tests that the graph builder properly expands modules.
+func TestBuiltinGraphBuilder_modules(t *testing.T) {
+	b := &BuiltinGraphBuilder{
+		Root: testModule(t, "graph-builder-modules"),
+	}
+
+	g, err := b.Build(RootModulePath)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(testBuiltinGraphBuilderModuleStr)
+	if actual != expected {
+		t.Fatalf("bad: %s", actual)
+	}
+}
+
 const testBuiltinGraphBuilderBasicStr = `
 aws_instance.db
   provider.aws
@@ -37,3 +55,15 @@ aws_instance.web
   provider.aws
 provider.aws
 `
+
+const testBuiltinGraphBuilderModuleStr = `
+aws_instance.web
+  aws_security_group.firewall
+  module.consul (expanded)
+  provider.aws
+aws_security_group.firewall
+  provider.aws
+module.consul (expanded)
+  aws_security_group.firewall
+provider.aws
+`

terraform/test-fixtures/graph-builder-modules/consul/main.tf

@@ -0,0 +1,2 @@
+provider "aws" {}
+resource "aws_instance" "server" {}

terraform/test-fixtures/graph-builder-modules/main.tf

@@ -0,0 +1,16 @@
+module "consul" {
+    foo = "${aws_security_group.firewall.foo}"
+    source = "./consul"
+}
+
+provider "aws" {}
+
+resource "aws_security_group" "firewall" {}
+
+resource "aws_instance" "web" {
+    security_groups = [
+        "foo",
+        "${aws_security_group.firewall.foo}",
+        "${module.consul.security_group}"
+    ]
+}