feat:db master and replica update solution for mysql

examples/mysql-ha/main.tf

@@ -80,6 +80,7 @@ module "mysql" {
 
   // Read replica configurations
   read_replica_name_suffix = "-test"
+  replica_database_version = "MYSQL_5_7"
   read_replicas = [
     {
       name                  = "0"

modules/mysql/README.md

@@ -40,6 +40,7 @@ Note: CloudSQL provides [disk autoresize](https://cloud.google.com/sql/docs/mysq
 | read\_replica\_name\_suffix | The optional suffix to add to the read instance name | `string` | `""` | no |
 | read\_replicas | List of read replicas to create. Encryption key is required for replica in different region. For replica in same region as master set encryption\_key\_name = null | <pre>list(object({<br>    name                  = string<br>    tier                  = string<br>    zone                  = string<br>    availability_type     = string<br>    disk_type             = string<br>    disk_autoresize       = bool<br>    disk_autoresize_limit = number<br>    disk_size             = string<br>    user_labels           = map(string)<br>    database_flags = list(object({<br>      name  = string<br>      value = string<br>    }))<br>    ip_configuration = object({<br>      authorized_networks = list(map(string))<br>      ipv4_enabled        = bool<br>      private_network     = string<br>      require_ssl         = bool<br>      allocated_ip_range  = string<br>    })<br>    encryption_key_name = string<br>  }))</pre> | `[]` | no |
 | region | The region of the Cloud SQL resources | `string` | `"us-central1"` | no |
+| replica\_database\_version | The read replica database version to use. This var should only be used during a database update. The update sequence 1. read-replica 2. master, setting this to an updated version will cause the replica to update, then you may update the master with the var database\_version and remove this field after update is complete | `string` | `""` | no |
 | secondary\_zone | The preferred zone for the secondary/failover instance, it should be something like: `us-central1-a`, `us-east1-c`. | `string` | `null` | no |
 | tier | The tier for the master instance. | `string` | `"db-n1-standard-1"` | no |
 | update\_timeout | The optional timout that is applied to limit long database updates. | `string` | `"10m"` | no |

modules/mysql/read_replica.tf

@@ -25,7 +25,7 @@ resource "google_sql_database_instance" "replicas" {
   for_each             = local.replicas
   project              = var.project_id
   name                 = "${local.master_instance_name}-replica${var.read_replica_name_suffix}${each.value.name}"
-  database_version     = var.database_version
+  database_version     = var.replica_database_version != "" ? var.replica_database_version : var.database_version
   region               = join("-", slice(split("-", lookup(each.value, "zone", var.zone)), 0, 2))
   master_instance_name = google_sql_database_instance.default.name
   deletion_protection  = var.read_replica_deletion_protection

modules/mysql/variables.tf

@@ -30,6 +30,12 @@ variable "random_instance_name" {
   default     = false
 }
 
+variable "replica_database_version" {
+  description = "The read replica database version to use. This var should only be used during a database update. The update sequence 1. read-replica 2. master, setting this to an updated version will cause the replica to update, then you may update the master with the var database_version and remove this field after update is complete"
+  type        = string
+  default     = ""
+}
+
 // required
 variable "database_version" {
   description = "The database version to use"