dynamodb/table: Fix ability to disable dynamodb table ttl

.changelog/40046.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+resource/aws_dynamodb_table: Allow table TTL to be disabled by allowing `ttl[0].attribute_name` to be set when `ttl[0].enabled` is false
+```

internal/service/dynamodb/table.go

@@ -473,6 +473,14 @@ func resourceTable() *schema.Resource {
 						"attribute_name": {
 							Type:     schema.TypeString,
 							Optional: true,
+							DiffSuppressFunc: func(k, old, new string, d *schema.ResourceData) bool {
+								// AWS requires the attribute name to be set when disabling TTL but
+								// does not return it so it causes a diff.
+								if old == "" && new != "" && !d.Get("ttl.0.enabled").(bool) {
+									return true
+								}
+								return false
+							},
 						},
 						names.AttrEnabled: {
 							Type:     schema.TypeBool,
@@ -2628,13 +2636,9 @@ func ttlPlantimeValidate(ttlPath cty.Path, ttl cty.Value, diags *diag.Diagnostic
 				errs.PathString(ttlPath.GetAttr("attribute_name")),
 			))
 		}
-	} else {
-		if !(attribute.IsNull() || attribute.AsString() == "") {
-			*diags = append(*diags, errs.NewAttributeConflictsWhenError(
-				ttlPath.GetAttr("attribute_name"),
-				ttlPath.GetAttr(names.AttrEnabled),
-				"false",
-			))
-		}
 	}
+
+	// !! Not a validation error for attribute_name to be set when enabled is false !!
+	// AWS *requires* attribute_name to be set when disabling TTL but does not return it, causing a diff.
+	// The diff is handled by DiffSuppressFunc of attribute_name.
 }

internal/service/dynamodb/table_test.go

@@ -10,6 +10,7 @@ import (
 	"reflect"
 	"regexp"
 	"testing"
+	"time"
 
 	"github.com/YakDriver/regexache"
 	"github.com/aws/aws-sdk-go-v2/aws"
@@ -1557,7 +1558,7 @@ func TestAccDynamoDBTable_TTL_disabled(t *testing.T) {
 
 // TTL tests must be split since it can only be updated once per hour
 // ValidationException: Time to live has been modified multiple times within a fixed interval
-func TestAccDynamoDBTable_TTL_update(t *testing.T) {
+func TestAccDynamoDBTable_TTL_updateEnable(t *testing.T) {
 	ctx := acctest.Context(t)
 	var table awstypes.TableDescription
 	resourceName := "aws_dynamodb_table.test"
@@ -1606,6 +1607,83 @@ func TestAccDynamoDBTable_TTL_update(t *testing.T) {
 	})
 }
 
+// TestAccDynamoDBTable_TTL_updateDisable takes an hour because AWS does not allow disabling TTL
+// for an hour after it was enabled. Otherwise, it will return the following error:
+// ValidationException: Time to live has been modified multiple times within a fixed interval
+// https://github.com/hashicorp/terraform-provider-aws/issues/39195
+func TestAccDynamoDBTable_TTL_updateDisable(t *testing.T) {
+	ctx := acctest.Context(t)
+	if testing.Short() {
+		t.Skip("skipping long-running test in short mode")
+	}
+
+	var table awstypes.TableDescription
+	resourceName := "aws_dynamodb_table.test"
+	rName := sdkacctest.RandomWithPrefix(acctest.ResourcePrefix)
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:                 func() { acctest.PreCheck(ctx, t) },
+		ErrorCheck:               acctest.ErrorCheck(t, names.DynamoDBServiceID),
+		ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories,
+		CheckDestroy:             testAccCheckTableDestroy(ctx),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccTableConfig_timeToLive(rName, rName, true),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					testAccCheckInitialTableExists(ctx, resourceName, &table),
+				),
+				ConfigStateChecks: []statecheck.StateCheck{
+					statecheck.ExpectKnownValue(resourceName, tfjsonpath.New("ttl"), knownvalue.ListExact([]knownvalue.Check{
+						knownvalue.ObjectExact(map[string]knownvalue.Check{
+							"attribute_name":  knownvalue.StringExact(rName),
+							names.AttrEnabled: knownvalue.Bool(true),
+						}),
+					})),
+				},
+			},
+			{
+				ResourceName:      resourceName,
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+			{
+				PreConfig: func() {
+					// AWS does not allow disabling TTL for an hour after it was enabled. Otherwise, it
+					// will return the following error: ValidationException: Time to live has been
+					// modified multiple times within a fixed interval
+					time.Sleep(60 * time.Minute)
+				},
+				Config: testAccTableConfig_timeToLive(rName, rName, false), // can't disable without attribute_name (2nd arg)
+				Check: resource.ComposeAggregateTestCheckFunc(
+					testAccCheckInitialTableExists(ctx, resourceName, &table),
+				),
+				ConfigStateChecks: []statecheck.StateCheck{
+					statecheck.ExpectKnownValue(resourceName, tfjsonpath.New("ttl"), knownvalue.ListExact([]knownvalue.Check{
+						knownvalue.ObjectExact(map[string]knownvalue.Check{
+							"attribute_name":  knownvalue.StringExact(""), // set attribute_name, but returned empty; diff suppressed
+							names.AttrEnabled: knownvalue.Bool(false),
+						}),
+					})),
+				},
+			},
+			{
+				Config: testAccTableConfig_timeToLive(rName, rName, false),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					testAccCheckInitialTableExists(ctx, resourceName, &table),
+				),
+				ConfigStateChecks: []statecheck.StateCheck{
+					statecheck.ExpectKnownValue(resourceName, tfjsonpath.New("ttl"), knownvalue.ListExact([]knownvalue.Check{
+						knownvalue.ObjectExact(map[string]knownvalue.Check{
+							"attribute_name":  knownvalue.StringExact(""),
+							names.AttrEnabled: knownvalue.Bool(false),
+						}),
+					})),
+				},
+			},
+		},
+	})
+}
+
 func TestAccDynamoDBTable_TTL_validate(t *testing.T) {
 	ctx := acctest.Context(t)
 	rName := sdkacctest.RandomWithPrefix(acctest.ResourcePrefix)