Allow upgrade major version on RDS Aurora when use custom parameter groups

.changelog/18820.txt

@@ -0,0 +1,7 @@
+```release-notes:bug
+resource/aws_rds_cluster_instance: Remove `force new resource` on the `engine_version` parameter to allow upgrade without remove instances.
+```
+
+```release-notes:enhancement
+resource/aws_rds_cluster: Add `db_instance_parameter_group_name` attribute to allow major version upgrade when use custom parameter groups.
+```

aws/resource_aws_rds_cluster.go

@@ -117,6 +117,12 @@ func resourceAwsRDSCluster() *schema.Resource {
 				Computed: true,
 			},
 
+			"db_instance_parameter_group_name": {
+				Type:     schema.TypeString,
+				Optional: true,
+				Computed: true,
+			},
+
 			"deletion_protection": {
 				Type:     schema.TypeBool,
 				Optional: true,
@@ -1197,6 +1203,11 @@ func resourceAwsRDSClusterUpdate(d *schema.ResourceData, meta interface{}) error
 		requestUpdate = true
 	}
 
+	if d.HasChange("db_instance_parameter_group_name") {
+		req.DBInstanceParameterGroupName = aws.String(d.Get("db_instance_parameter_group_name").(string))
+		requestUpdate = true
+	}
+
 	if d.HasChange("deletion_protection") {
 		req.DeletionProtection = aws.Bool(d.Get("deletion_protection").(bool))
 		requestUpdate = true

aws/resource_aws_rds_cluster_instance.go

@@ -102,7 +102,6 @@ func resourceAwsRDSClusterInstance() *schema.Resource {
 			"engine_version": {
 				Type:     schema.TypeString,
 				Optional: true,
-				ForceNew: true,
 				Computed: true,
 			},
 

aws/resource_aws_rds_cluster_test.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"log"
 	"regexp"
+	"strings"
 	"testing"
 	"time"
 
@@ -209,6 +210,58 @@ func TestAccAWSRDSCluster_AllowMajorVersionUpgrade(t *testing.T) {
 	})
 }
 
+func TestAccAWSRDSCluster_AllowMajorVersionUpgradeWithCustomParameters(t *testing.T) {
+	var dbCluster1, dbCluster2 rds.DBCluster
+	rName := acctest.RandomWithPrefix("tf-acc-test")
+	resourceName := "aws_rds_cluster.test"
+	// If these hardcoded versions become a maintenance burden, use DescribeDBEngineVersions
+	// either by having a new data source created or implementing the testing similar
+	// to TestAccAWSDmsReplicationInstance_EngineVersion
+	engine := "aurora-postgresql"
+	engineVersion1 := "11.9"
+	engineVersion2 := "12.4"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		ErrorCheck:   testAccErrorCheck(t, rds.EndpointsID),
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckAWSClusterDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAWSClusterConfig_AllowMajorVersionUpgradeWithCustomParameters(rName, true, engine, engineVersion1),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSClusterExists(resourceName, &dbCluster1),
+					resource.TestCheckResourceAttr(resourceName, "allow_major_version_upgrade", "true"),
+					resource.TestCheckResourceAttr(resourceName, "engine", engine),
+					resource.TestCheckResourceAttr(resourceName, "engine_version", engineVersion1),
+				),
+			},
+			{
+				ResourceName:      resourceName,
+				ImportState:       true,
+				ImportStateVerify: true,
+				ImportStateVerifyIgnore: []string{
+					"allow_major_version_upgrade",
+					"apply_immediately",
+					"cluster_identifier_prefix",
+					"master_password",
+					"skip_final_snapshot",
+					"db_instance_parameter_group_name",
+				},
+			},
+			{
+				Config: testAccAWSClusterConfig_AllowMajorVersionUpgradeWithCustomParameters(rName, true, engine, engineVersion2),
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckAWSClusterExists(resourceName, &dbCluster2),
+					resource.TestCheckResourceAttr(resourceName, "allow_major_version_upgrade", "true"),
+					resource.TestCheckResourceAttr(resourceName, "engine", engine),
+					resource.TestCheckResourceAttr(resourceName, "engine_version", engineVersion2),
+				),
+			},
+		},
+	})
+}
+
 func TestAccAWSRDSCluster_OnlyMajorVersion(t *testing.T) {
 	var dbCluster1 rds.DBCluster
 	rName := acctest.RandomWithPrefix("tf-acc-test")
@@ -2569,6 +2622,60 @@ resource "aws_rds_cluster_instance" "test" {
 `, allowMajorVersionUpgrade, rName, engine, engineVersion)
 }
 
+func testAccAWSClusterConfig_AllowMajorVersionUpgradeWithCustomParameters(rName string, allowMajorVersionUpgrade bool, engine string, engineVersion string) string {
+	return fmt.Sprintf(`
+resource "aws_rds_cluster" "test" {
+  allow_major_version_upgrade      = %[1]t
+  apply_immediately                = true
+  cluster_identifier               = %[2]q
+  engine                           = %[3]q
+  engine_version                   = %[4]q
+  master_password                  = "mustbeeightcharaters"
+  master_username                  = "test"
+  db_cluster_parameter_group_name  = aws_rds_cluster_parameter_group.cluster_parameters.name
+  db_instance_parameter_group_name = aws_db_parameter_group.db_parameters.name
+  skip_final_snapshot              = true
+}
+
+data "aws_rds_orderable_db_instance" "test" {
+  engine                     = aws_rds_cluster.test.engine
+  engine_version             = aws_rds_cluster.test.engine_version
+  preferred_instance_classes = ["db.t3.medium", "db.r5.large", "db.r6g.large"]
+}
+
+# Upgrading requires a healthy primary instance
+resource "aws_rds_cluster_instance" "test" {
+  apply_immediately       = true
+  cluster_identifier      = aws_rds_cluster.test.id
+  engine                  = data.aws_rds_orderable_db_instance.test.engine
+  engine_version          = data.aws_rds_orderable_db_instance.test.engine_version
+  identifier              = %[2]q
+  instance_class          = data.aws_rds_orderable_db_instance.test.instance_class
+  db_parameter_group_name = aws_db_parameter_group.db_parameters.name
+}
+
+# Custom cluster parameter group
+resource "aws_rds_cluster_parameter_group" "cluster_parameters" {
+  name_prefix = %[2]q
+  family      = %[5]q
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+
+# Custom instance parameter group
+resource "aws_db_parameter_group" "db_parameters" {
+  name_prefix = %[2]q
+  family      = %[5]q
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+`, allowMajorVersionUpgrade, rName, engine, engineVersion, engine+strings.Split(engineVersion, ".")[0])
+}
+
 func testAccAWSClusterConfig_MajorVersionOnly(rName string, allowMajorVersionUpgrade bool, engine string, engineVersion string) string {
 	return fmt.Sprintf(`
 resource "aws_rds_cluster" "test" {

website/docs/r/rds_cluster.html.markdown

@@ -98,7 +98,10 @@ resource "aws_rds_cluster" "example" {
 ## Argument Reference
 
 For more detailed documentation about each argument, refer to
-the [AWS official documentation](https://docs.aws.amazon.com/cli/latest/reference/rds/create-db-cluster.html).
+the AWS official documentation :
+
+* [create-db-cluster](https://docs.aws.amazon.com/cli/latest/reference/rds/create-db-cluster.html).
+* [modify-db-cluster](https://docs.aws.amazon.com/cli/latest/reference/rds/modify-db-cluster.html)
 
 The following arguments are supported:
 
@@ -112,6 +115,7 @@ The following arguments are supported:
 * `copy_tags_to_snapshot` – (Optional, boolean) Copy all Cluster `tags` to snapshots. Default is `false`.
 * `database_name` - (Optional) Name for an automatically created database on cluster creation. There are different naming restrictions per database engine: [RDS Naming Constraints][5]
 * `db_cluster_parameter_group_name` - (Optional) A cluster parameter group to associate with the cluster.
+* `db_instance_parameter_group_name` - (Optional) An instance parameter group to associate to all instances of the DB cluster. This parameter is only valid in combination with the `allow_major_version_upgrade` parameter.
 * `db_subnet_group_name` - (Optional) A DB subnet group to associate with this DB instance. **NOTE:** This must match the `db_subnet_group_name` specified on every [`aws_rds_cluster_instance`](/docs/providers/aws/r/rds_cluster_instance.html) in the cluster.
 * `deletion_protection` - (Optional) If the DB instance should have deletion protection enabled. The database can't be deleted when this value is set to `true`. The default is `false`.
 * `enable_http_endpoint` - (Optional) Enable HTTP endpoint (data API). Only valid when `engine_mode` is set to `serverless`.

website/docs/r/rds_cluster_instance.html.markdown

@@ -58,7 +58,7 @@ The following arguments are supported:
 For information on the difference between the available Aurora MySQL engines
 see [Comparison between Aurora MySQL 1 and Aurora MySQL 2](https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/AuroraMySQL.Updates.20180206.html)
 in the Amazon RDS User Guide.
-* `engine_version` - (Optional, Forces new resource) The database engine version. When managing the engine version in the cluster, it is recommended to add the [lifecycle `ignore_changes` configuration](https://www.terraform.io/docs/configuration/meta-arguments/lifecycle.html#ignore_changes) for this argument to prevent Terraform from proposing changes to the instance engine version directly.
+* `engine_version` - (Optional) The database engine version.
 * `instance_class` - (Required) The instance class to use. For details on CPU
 and memory, see [Scaling Aurora DB Instances][4]. Aurora uses `db.*` instance classes/types. Please see [AWS Documentation][7] for currently available instance classes and complete details.
 * `publicly_accessible` - (Optional) Bool to control if instance is publicly accessible.