terraform: module input to another module doesn't error [GH-659]

CHANGELOG.md

@@ -20,6 +20,8 @@ BUG FIXES:
       diffing lists. [GH-661]
   * core: fix crash where module inputs weren't strings, and add more
       validation around invalid types here. [GH-624]
+  * core: fix error when using a computed module output as an input to
+      another module. [GH-659]
   * provider/aws: Fix crash case when internet gateway is not attached
       to any VPC. [GH-664]
   * provider/aws: `vpc_id` is no longer required. [GH-667]

terraform/context.go

@@ -1623,10 +1623,7 @@ func (c *walkContext) computeModuleVariable(
 	// Get that module from our state
 	mod := c.Context.state.ModuleByPath(path)
 	if mod == nil {
-		return "", fmt.Errorf(
+		return "", nil
-			"Module '%s' not found for variable '%s'",
-			strings.Join(path[1:], "."),
-			v.FullKey())
 	}
 
 	value, ok := mod.Outputs[v.Field]

terraform/context_test.go

@@ -4362,6 +4362,22 @@ func TestContextRefresh_moduleInputComputedOutput(t *testing.T) {
 	}
 }
 
+func TestContextRefresh_moduleVarModule(t *testing.T) {
+	m := testModule(t, "refresh-module-var-module")
+	p := testProvider("aws")
+	p.DiffFn = testDiffFn
+	ctx := testContext(t, &ContextOpts{
+		Module: m,
+		Providers: map[string]ResourceProviderFactory{
+			"aws": testProviderFuncFixed(p),
+		},
+	})
+
+	if _, err := ctx.Refresh(); err != nil {
+		t.Fatalf("err: %s", err)
+	}
+}
+
 // GH-70
 func TestContextRefresh_noState(t *testing.T) {
 	p := testProvider("aws")