Add inequality check to ignore redundant diff attributes

terraform/diff.go

@@ -396,6 +396,11 @@ type ResourceAttrDiff struct {
 	Type        DiffAttrType
 }
 
+// Modified returns the inequality of Old and New for this attr
+func (d *ResourceAttrDiff) Modified() bool {
+	return d.Old != d.New
+}
+
 // Empty returns true if the diff for this attr is neutral
 func (d *ResourceAttrDiff) Empty() bool {
 	return d.Old == d.New && !d.NewComputed && !d.NewRemoved

terraform/eval_diff.go

@@ -258,12 +258,14 @@ func (n *EvalDiff) processIgnoreChanges(diff *InstanceDiff) error {
 		for _, v := range containers {
 			if v.keepDiff() {
 				// At least one key has changes, so list all the sibling keys
-				// to keep in the diff.
+				// to keep in the diff if any values have changed
 				for k := range v {
+					if v[k].Modified() {
 						keep[k] = true
 					}
 				}
 			}
+		}
 
 		for k, v := range attrs {
 			if (v.Empty() || v.NewComputed) && !keep[k] {

terraform/eval_diff_test.go

@@ -3,6 +3,8 @@ package terraform
 import (
 	"reflect"
 	"testing"
+
+	"github.com/hashicorp/terraform/config"
 )
 
 func TestEvalFilterDiff(t *testing.T) {
@@ -76,3 +78,69 @@ func TestEvalFilterDiff(t *testing.T) {
 		}
 	}
 }
+
+func TestProcessIgnoreChangesOnResourceIgnoredWithRequiresNew(t *testing.T) {
+	var evalDiff *EvalDiff
+	var instanceDiff *InstanceDiff
+
+	var testDiffs = func(ignoreChanges []string, newAttribute string) (*EvalDiff, *InstanceDiff) {
+		return &EvalDiff{
+				Resource: &config.Resource{
+					Lifecycle: config.ResourceLifecycle{
+						IgnoreChanges: ignoreChanges,
+					},
+				},
+			},
+			&InstanceDiff{
+				Destroy: true,
+				Attributes: map[string]*ResourceAttrDiff{
+					"resource.changed": {
+						RequiresNew: true,
+						Type:        DiffAttrInput,
+						Old:         "old",
+						New:         "new",
+					},
+					"resource.unchanged": {
+						Old: "unchanged",
+						New: newAttribute,
+					},
+				},
+			}
+	}
+
+	evalDiff, instanceDiff = testDiffs([]string{"resource.changed"}, "unchanged")
+	err := evalDiff.processIgnoreChanges(instanceDiff)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if len(instanceDiff.Attributes) > 0 {
+		t.Fatalf("Expected all resources to be ignored, found %d", len(instanceDiff.Attributes))
+	}
+
+	evalDiff, instanceDiff = testDiffs([]string{}, "unchanged")
+	err = evalDiff.processIgnoreChanges(instanceDiff)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if len(instanceDiff.Attributes) != 2 {
+		t.Fatalf("Expected 2 resources to be found, found %d", len(instanceDiff.Attributes))
+	}
+
+	evalDiff, instanceDiff = testDiffs([]string{"resource.changed"}, "changed")
+	err = evalDiff.processIgnoreChanges(instanceDiff)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if len(instanceDiff.Attributes) != 1 {
+		t.Fatalf("Expected 1 resource to be found, found %d", len(instanceDiff.Attributes))
+	}
+
+	evalDiff, instanceDiff = testDiffs([]string{}, "changed")
+	err = evalDiff.processIgnoreChanges(instanceDiff)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+	if len(instanceDiff.Attributes) != 2 {
+		t.Fatalf("Expected 2 resource to be found, found %d", len(instanceDiff.Attributes))
+	}
+}

terraform/terraform_test.go

@@ -1675,10 +1675,7 @@ aws_instance.foo:
 const testTFPlanDiffIgnoreChangesWithFlatmaps = `
 UPDATE: aws_instance.foo
   lst.#:   "1" => "2"
-  lst.0:   "j" => "j"
   lst.1:   "" => "k"
-  set.#:   "1" => "1"
-  set.0.a: "1" => "1"
   set.0.b: "" => "2"
   type:    "" => "aws_instance"
 `