From 39edc5dc044999d5486cc342c8df79f39593aaf2 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Mon, 20 Oct 2014 14:23:06 -0700
Subject: [PATCH] helper/schema: diffing maps that are computed should not
 result in change

---
 helper/schema/schema.go      |  5 +++++
 helper/schema/schema_test.go | 21 +++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/helper/schema/schema.go b/helper/schema/schema.go
index 3650123d36..6905325288 100644
--- a/helper/schema/schema.go
+++ b/helper/schema/schema.go
@@ -580,6 +580,11 @@ func (m schemaMap) diffMap(
 		return fmt.Errorf("%s: %s", k, err)
 	}
 
+	// If the new map is nil and we're computed, then ignore it.
+	if n == nil && schema.Computed {
+		return nil
+	}
+
 	// Now we compare, preferring values from the config map
 	for k, v := range configMap {
 		old := stateMap[k]
diff --git a/helper/schema/schema_test.go b/helper/schema/schema_test.go
index 70388f5690..d5ee09a6c5 100644
--- a/helper/schema/schema_test.go
+++ b/helper/schema/schema_test.go
@@ -1191,6 +1191,27 @@ func TestSchemaMap_Diff(t *testing.T) {
 			Err: false,
 		},
 
+		{
+			Schema: map[string]*Schema{
+				"vars": &Schema{
+					Type:     TypeMap,
+					Computed: true,
+				},
+			},
+
+			State: &terraform.InstanceState{
+				Attributes: map[string]string{
+					"vars.foo": "bar",
+				},
+			},
+
+			Config: nil,
+
+			Diff: nil,
+
+			Err: false,
+		},
+
 		{
 			Schema: map[string]*Schema{
 				"config_vars": &Schema{