terraform: modules are put into the graph

terraform/graph.go

@@ -50,6 +50,12 @@ type GraphOpts struct {
 // graph. This node is just a placemarker and has no associated functionality.
 const GraphRootNode = "root"
 
+// GraphNodeModule is a node type in the graph that represents a module
+// that will be created/managed.
+type GraphNodeModule struct {
+	Config *config.Module
+}
+
 // GraphNodeResource is a node type in the graph that represents a resource
 // that will be created or managed. Unlike the GraphNodeResourceMeta node,
 // this represents a _single_, _resource_ to be managed, not a set of resources
@@ -108,6 +114,9 @@ func Graph(opts *GraphOpts) (*depgraph.Graph, error) {
 	// and not "orphans" (that are in the state, but not in the config).
 	graphAddConfigResources(g, opts.Config, opts.State)
 
+	// Add the modules that are in the configuration.
+	graphAddConfigModules(g, opts)
+
 	// Add explicit dependsOn dependencies to the graph
 	graphAddExplicitDeps(g)
 
@@ -220,6 +229,33 @@ func graphInitState(s *State, g *depgraph.Graph) {
 	}
 }
 
+// graphAddConfigModules adds the modules from a configuration structure
+// into the graph, expanding each to their own sub-graph.
+func graphAddConfigModules(g *depgraph.Graph, opts *GraphOpts) {
+	c := opts.Config
+
+	// Just short-circuit the whole thing if we don't have modules
+	if len(c.Modules) == 0 {
+		return
+	}
+
+	// Build the list of nouns to add to the graph
+	nounsList := make([]*depgraph.Noun, 0, len(c.Modules))
+	for _, m := range c.Modules {
+		name := fmt.Sprintf("module.%s", m.Name)
+		n := &depgraph.Noun{
+			Name: name,
+			Meta: &GraphNodeModule{
+				Config: m,
+			},
+		}
+
+		nounsList = append(nounsList, n)
+	}
+
+	g.Nouns = append(g.Nouns, nounsList...)
+}
+
 // configGraph turns a configuration structure into a dependency graph.
 func graphAddConfigResources(
 	g *depgraph.Graph, c *config.Config, s *State) {
@@ -752,18 +788,21 @@ func graphAddRoot(g *depgraph.Graph) {
 // based on variable values.
 func graphAddVariableDeps(g *depgraph.Graph) {
 	for _, n := range g.Nouns {
-		var vars map[string]config.InterpolatedVariable
 		switch m := n.Meta.(type) {
+		case *GraphNodeModule:
+			vars := m.Config.RawConfig.Variables
+			nounAddVariableDeps(g, n, vars, false)
+
 		case *GraphNodeResource:
 			if m.Config != nil {
 				// Handle the resource variables
-				vars = m.Config.RawConfig.Variables
+				vars := m.Config.RawConfig.Variables
 				nounAddVariableDeps(g, n, vars, false)
 			}
 
 			// Handle the variables of the resource provisioners
 			for _, p := range m.Resource.Provisioners {
-				vars = p.RawConfig.Variables
+				vars := p.RawConfig.Variables
 				nounAddVariableDeps(g, n, vars, true)
 
 				vars = p.ConnInfo.Variables
@@ -771,10 +810,11 @@ func graphAddVariableDeps(g *depgraph.Graph) {
 			}
 
 		case *GraphNodeResourceProvider:
-			vars = m.Config.RawConfig.Variables
+			vars := m.Config.RawConfig.Variables
 			nounAddVariableDeps(g, n, vars, false)
 
 		default:
+			// Other node types don't have dependencies or we don't support it
 			continue
 		}
 	}
@@ -854,15 +894,20 @@ func nounAddVariableDeps(
 	n *depgraph.Noun,
 	vars map[string]config.InterpolatedVariable,
 	removeSelf bool) {
-	for _, v := range vars {
-		// Only resource variables impose dependencies
-		rv, ok := v.(*config.ResourceVariable)
-		if !ok {
-			continue
+	for _, rawV := range vars {
+		var name string
+		var target *depgraph.Noun
+
+		switch v := rawV.(type) {
+		case *config.ModuleVariable:
+			name = fmt.Sprintf("module.%s", v.Name)
+			target = g.Noun(name)
+		case *config.ResourceVariable:
+			name = v.ResourceId()
+			target = g.Noun(v.ResourceId())
+		default:
 		}
 
-		// Find the target
-		target := g.Noun(rv.ResourceId())
 		if target == nil {
 			continue
 		}
@@ -875,7 +920,7 @@ func nounAddVariableDeps(
 
 		// Build the dependency
 		dep := &depgraph.Dependency{
-			Name:   rv.ResourceId(),
+			Name:   name,
 			Source: n,
 			Target: target,
 		}

terraform/graph_test.go

@@ -81,6 +81,21 @@ func TestGraph_dependsOnCount(t *testing.T) {
 	}
 }
 
+func TestGraph_modules(t *testing.T) {
+	config := testConfig(t, "graph-modules")
+
+	g, err := Graph(&GraphOpts{Config: config})
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(g.String())
+	expected := strings.TrimSpace(testTerraformGraphModulesStr)
+	if actual != expected {
+		t.Fatalf("bad:\n\n%s", actual)
+	}
+}
+
 func TestGraph_state(t *testing.T) {
 	config := testConfig(t, "graph-basic")
 	state := &State{
@@ -767,6 +782,23 @@ root
   root -> aws_load_balancer.weblb
 `
 
+const testTerraformGraphModulesStr = `
+root: root
+aws_instance.web
+  aws_instance.web -> aws_security_group.firewall
+  aws_instance.web -> module.consul
+  aws_instance.web -> provider.aws
+aws_security_group.firewall
+  aws_security_group.firewall -> provider.aws
+module.consul
+  module.consul -> aws_security_group.firewall
+provider.aws
+root
+  root -> aws_instance.web
+  root -> aws_security_group.firewall
+  root -> module.consul
+`
+
 const testTerraformGraphStateStr = `
 root: root
 aws_instance.old

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

@@ -0,0 +1,15 @@
+module "consul" {
+    foo = "${aws_security_group.firewall.foo}"
+}
+
+provider "aws" {}
+
+resource "aws_security_group" "firewall" {}
+
+resource "aws_instance" "web" {
+    security_groups = [
+        "foo",
+        "${aws_security_group.firewall.foo}",
+        "${module.consul.security_group}"
+    ]
+}