terraform: computed input variables work to modules

terraform/context.go

@@ -889,6 +889,11 @@ func (c *walkContext) genericWalkFn(cb genericWalkFunc) depgraph.WalkFunc {
 				for k, v := range rc.Config {
 					wc.Variables[k] = v.(string)
 				}
+				for k, _ := range rc.Raw {
+					if _, ok := wc.Variables[k]; !ok {
+						wc.Variables[k] = config.UnknownVariableValue
+					}
+				}
 			}
 
 			return wc.Walk()

terraform/context_test.go

@@ -1474,6 +1474,29 @@ func TestContextPlan_moduleInput(t *testing.T) {
 	}
 }
 
+func TestContextPlan_moduleInputComputed(t *testing.T) {
+	m := testModule(t, "plan-module-input-computed")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Module: m,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	plan, err := ctx.Plan(nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	actual := strings.TrimSpace(plan.String())
+	expected := strings.TrimSpace(testTerraformPlanModuleInputComputedStr)
+	if actual != expected {
+		t.Fatalf("bad:\n%s", actual)
+	}
+}
+
 func TestContextPlan_moduleInputFromVar(t *testing.T) {
 	m := testModule(t, "plan-module-input-var")
 	p := testProvider("aws")

terraform/terraform_test.go

@@ -528,6 +528,23 @@ STATE:
 <no state>
 `
 
+const testTerraformPlanModuleInputComputedStr = `
+DIFF:
+
+CREATE: aws_instance.bar
+  foo:  "" => "<computed>"
+  type: "" => "aws_instance"
+
+module.child:
+  CREATE: aws_instance.foo
+    foo:  "" => "<computed>"
+    type: "" => "aws_instance"
+
+STATE:
+
+<no state>
+`
+
 const testTerraformPlanModuleInputVarStr = `
 DIFF:
 

terraform/test-fixtures/plan-module-input-computed/child/main.tf

@@ -0,0 +1,5 @@
+variable "input" {}
+
+resource "aws_instance" "foo" {
+    foo = "${var.input}"
+}

terraform/test-fixtures/plan-module-input-computed/main.tf

@@ -0,0 +1,8 @@
+module "child" {
+    input = "${aws_instance.bar.foo}"
+    source = "./child"
+}
+
+resource "aws_instance" "bar" {
+    compute = "foo"
+}