From b335918c3c49c24455904328c0c59251a919a796 Mon Sep 17 00:00:00 2001
From: Alisdair McDiarmid <alisdair@users.noreply.github.com>
Date: Mon, 2 Nov 2020 10:22:37 -0500
Subject: [PATCH] backend: Only show root module output changes

When rendering planned output changes, we need to filter the plan's
output changes to ensure that only root module outputs which have
changed are rendered. Otherwise we will render changes for submodule
outputs, and (with concise diff disabled) render unchanged outputs also.
---
 backend/local/backend_plan.go                      | 14 ++++++++++++--
 .../local/testdata/plan-outputs-changed/main.tf    |  4 ++++
 .../plan-outputs-changed/submodule/main.tf         |  3 +++
 3 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 backend/local/testdata/plan-outputs-changed/submodule/main.tf

diff --git a/backend/local/backend_plan.go b/backend/local/backend_plan.go
index 0fbb0b58a..a5733473c 100644
--- a/backend/local/backend_plan.go
+++ b/backend/local/backend_plan.go
@@ -314,8 +314,18 @@ func RenderPlan(plan *plans.Plan, baseState *states.State, schemas *terraform.Sc
 
 	// If there is at least one planned change to the root module outputs
 	// then we'll render a summary of those too.
-	if len(plan.Changes.Outputs) > 0 {
-		ui.Output(colorize.Color("[reset]\n[bold]Changes to Outputs:[reset]" + format.OutputChanges(plan.Changes.Outputs, colorize)))
+	var changedRootModuleOutputs []*plans.OutputChangeSrc
+	for _, output := range plan.Changes.Outputs {
+		if !output.Addr.Module.IsRoot() {
+			continue
+		}
+		if output.ChangeSrc.Action == plans.NoOp {
+			continue
+		}
+		changedRootModuleOutputs = append(changedRootModuleOutputs, output)
+	}
+	if len(changedRootModuleOutputs) > 0 {
+		ui.Output(colorize.Color("[reset]\n[bold]Changes to Outputs:[reset]" + format.OutputChanges(changedRootModuleOutputs, colorize)))
 	}
 }
 
diff --git a/backend/local/testdata/plan-outputs-changed/main.tf b/backend/local/testdata/plan-outputs-changed/main.tf
index c1686a89e..1df236ff4 100644
--- a/backend/local/testdata/plan-outputs-changed/main.tf
+++ b/backend/local/testdata/plan-outputs-changed/main.tf
@@ -1,3 +1,7 @@
+module "submodule" {
+  source = "./submodule"
+}
+
 output "changed" {
   value = "after"
 }
diff --git a/backend/local/testdata/plan-outputs-changed/submodule/main.tf b/backend/local/testdata/plan-outputs-changed/submodule/main.tf
new file mode 100644
index 000000000..ae32f8aa1
--- /dev/null
+++ b/backend/local/testdata/plan-outputs-changed/submodule/main.tf
@@ -0,0 +1,3 @@
+output "foo" {
+  value = "bar"
+}