add reader_independent_scaling input

README.md

@@ -454,6 +454,7 @@ Available targets:
 | <a name="input_rds_ri_offering_type"></a> [rds\_ri\_offering\_type](#input\_rds\_ri\_offering\_type) | Offering type of reserved DB instances. Valid values are 'No Upfront', 'Partial Upfront', 'All Upfront'. | `string` | `""` | no |
 | <a name="input_rds_ri_reservation_id"></a> [rds\_ri\_reservation\_id](#input\_rds\_ri\_reservation\_id) | Customer-specified identifier to track the reservation of the reserved DB instance. | `string` | `null` | no |
 | <a name="input_reader_dns_name"></a> [reader\_dns\_name](#input\_reader\_dns\_name) | Name of the reader endpoint CNAME record to create in the parent DNS zone specified by `zone_id`. If left empty, the name will be auto-asigned using the format `replicas.var.name` | `string` | `""` | no |
+| <a name="input_reader_independent_scaling"></a> [reader\_independent\_scaling](#input\_reader\_independent\_scaling) | Whether to scale the readers independentl from the writer | `bool` | `false` | no |
 | <a name="input_regex_replace_chars"></a> [regex\_replace\_chars](#input\_regex\_replace\_chars) | Terraform regular expression (regex) string.<br/>Characters matching the regex will be removed from the ID elements.<br/>If not set, `"/[^a-zA-Z0-9-]/"` is used to remove all characters other than hyphens, letters and digits. | `string` | `null` | no |
 | <a name="input_replication_source_identifier"></a> [replication\_source\_identifier](#input\_replication\_source\_identifier) | ARN of a source DB cluster or DB instance if this DB cluster is to be created as a Read Replica | `string` | `""` | no |
 | <a name="input_restore_to_point_in_time"></a> [restore\_to\_point\_in\_time](#input\_restore\_to\_point\_in\_time) | List of point-in-time recovery options. Valid parameters are:<br/><br/>`source_cluster_identifier`<br/>  Identifier of the source database cluster from which to restore.<br/>`restore_type`:<br/>  Type of restore to be performed. Valid options are "full-copy" and "copy-on-write".<br/>`use_latest_restorable_time`:<br/>  Set to true to restore the database cluster to the latest restorable backup time. Conflicts with `restore_to_time`.<br/>`restore_to_time`:<br/>  Date and time in UTC format to restore the database cluster to. Conflicts with `use_latest_restorable_time`. | <pre>list(object({<br/>    source_cluster_identifier  = string<br/>    restore_type               = optional(string, "copy-on-write")<br/>    use_latest_restorable_time = optional(bool, true)<br/>    restore_to_time            = optional(string, null)<br/>  }))</pre> | `[]` | no |

docs/terraform.md

@@ -140,6 +140,7 @@
 | <a name="input_rds_ri_offering_type"></a> [rds\_ri\_offering\_type](#input\_rds\_ri\_offering\_type) | Offering type of reserved DB instances. Valid values are 'No Upfront', 'Partial Upfront', 'All Upfront'. | `string` | `""` | no |
 | <a name="input_rds_ri_reservation_id"></a> [rds\_ri\_reservation\_id](#input\_rds\_ri\_reservation\_id) | Customer-specified identifier to track the reservation of the reserved DB instance. | `string` | `null` | no |
 | <a name="input_reader_dns_name"></a> [reader\_dns\_name](#input\_reader\_dns\_name) | Name of the reader endpoint CNAME record to create in the parent DNS zone specified by `zone_id`. If left empty, the name will be auto-asigned using the format `replicas.var.name` | `string` | `""` | no |
+| <a name="input_reader_independent_scaling"></a> [reader\_independent\_scaling](#input\_reader\_independent\_scaling) | Whether to scale the readers independentl from the writer | `bool` | `false` | no |
 | <a name="input_regex_replace_chars"></a> [regex\_replace\_chars](#input\_regex\_replace\_chars) | Terraform regular expression (regex) string.<br/>Characters matching the regex will be removed from the ID elements.<br/>If not set, `"/[^a-zA-Z0-9-]/"` is used to remove all characters other than hyphens, letters and digits. | `string` | `null` | no |
 | <a name="input_replication_source_identifier"></a> [replication\_source\_identifier](#input\_replication\_source\_identifier) | ARN of a source DB cluster or DB instance if this DB cluster is to be created as a Read Replica | `string` | `""` | no |
 | <a name="input_restore_to_point_in_time"></a> [restore\_to\_point\_in\_time](#input\_restore\_to\_point\_in\_time) | List of point-in-time recovery options. Valid parameters are:<br/><br/>`source_cluster_identifier`<br/>  Identifier of the source database cluster from which to restore.<br/>`restore_type`:<br/>  Type of restore to be performed. Valid options are "full-copy" and "copy-on-write".<br/>`use_latest_restorable_time`:<br/>  Set to true to restore the database cluster to the latest restorable backup time. Conflicts with `restore_to_time`.<br/>`restore_to_time`:<br/>  Date and time in UTC format to restore the database cluster to. Conflicts with `use_latest_restorable_time`. | <pre>list(object({<br/>    source_cluster_identifier  = string<br/>    restore_type               = optional(string, "copy-on-write")<br/>    use_latest_restorable_time = optional(bool, true)<br/>    restore_to_time            = optional(string, null)<br/>  }))</pre> | `[]` | no |

main.tf

@@ -365,6 +365,7 @@ resource "aws_rds_cluster_instance" "default" {
   preferred_maintenance_window          = var.maintenance_window
   copy_tags_to_snapshot                 = var.copy_tags_to_snapshot
   ca_cert_identifier                    = var.ca_cert_identifier
+  promotion_tier                        = var.reader_independent_scaling ? 2 : 0
 
   dynamic "timeouts" {
     for_each = var.timeouts_configuration

variables.tf

@@ -378,6 +378,11 @@ variable "performance_insights_retention_period" {
   default     = null
 }
 
+variable "reader_independent_scaling" {
+  type        = bool
+  default     = false
+  description = "Whether to scale the readers independentl from the writer"
+}
 variable "autoscaling_enabled" {
   type        = bool
   default     = false