terraform: fix module output handling. Fixes #474

terraform/context.go

@@ -523,7 +523,7 @@ func (c *walkContext) Walk() error {
 		// On Apply, we prune so that we don't do outputs if we destroyed
 		mod.prune()
 	}
-	if len(mod.Resources) == 0 {
+	if len(mod.Resources) == 0 && len(conf.Resources) != 0 {
 		mod.Outputs = nil
 		return nil
 	}

terraform/context_test.go

@@ -913,6 +913,35 @@ func TestContextApply(t *testing.T) {
 	}
 }
 
+func TestContextApply_emptyModule(t *testing.T) {
+	m := testModule(t, "apply-empty-module")
+	p := testProvider("aws")
+	p.ApplyFn = testApplyFn
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Module: m,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	if _, err := ctx.Plan(nil); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	state, err := ctx.Apply()
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(state.String())
+	actual = strings.Replace(actual, "  ", "", -1)
+	expected := strings.TrimSpace(testTerraformApplyEmptyModuleStr)
+	if actual != expected {
+		t.Fatalf("bad: \n%s\nexpect:\n%s", actual, expected)
+	}
+}
+
 func TestContextApply_createBeforeDestroy(t *testing.T) {
 	m := testModule(t, "apply-good-create-before")
 	p := testProvider("aws")

terraform/state.go

@@ -294,12 +294,12 @@ func (m *ModuleState) GoString() string {
 }
 
 func (m *ModuleState) String() string {
-	if len(m.Resources) == 0 {
-		return "<no state>"
-	}
-
 	var buf bytes.Buffer
 
+	if len(m.Resources) == 0 {
+		buf.WriteString("<no state>")
+	}
+
 	names := make([]string, 0, len(m.Resources))
 	for name, _ := range m.Resources {
 		names = append(names, name)

terraform/terraform_test.go

@@ -164,6 +164,21 @@ aws_instance.foo:
   type = aws_instance
 `
 
+const testTerraformApplyEmptyModuleStr = `
+<no state>
+Outputs:
+
+end = XXXX
+
+module.child:
+<no state>
+Outputs:
+
+aws_access_key = YYYYY
+aws_route53_zone_id = XXXX
+aws_secret_key = ZZZZ
+`
+
 const testTerraformApplyDependsCreateBeforeStr = `
 aws_instance.lb:
   ID = foo

terraform/test-fixtures/apply-empty-module/child/main.tf

@@ -0,0 +1,11 @@
+output "aws_route53_zone_id" {
+    value = "XXXX"
+}
+
+output "aws_access_key" {
+    value = "YYYYY"
+}
+
+output "aws_secret_key" {
+    value = "ZZZZ"
+}

terraform/test-fixtures/apply-empty-module/main.tf

@@ -0,0 +1,7 @@
+module "child" {
+    source = "./child"
+}
+
+output "end" {
+    value = "${module.child.aws_route53_zone_id}"
+}