azurerm_mysql_flexible_server suggests in-place update for storage size down-scale

[sigv]

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Terraform Version

1.7.4

AzureRM Provider Version

3.93.0

Affected Resource(s)/Data Source(s)

azurerm_mysql_flexible_server

Terraform Configuration Files

# https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/mysql_flexible_server
# Example from documentation, with additional `storage` block.

resource "azurerm_resource_group" "example" {
  name     = "example-resources"
  location = "West Europe"
}

resource "azurerm_virtual_network" "example" {
  name                = "example-vn"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name
  address_space       = ["10.0.0.0/16"]
}

resource "azurerm_subnet" "example" {
  name                 = "example-sn"
  resource_group_name  = azurerm_resource_group.example.name
  virtual_network_name = azurerm_virtual_network.example.name
  address_prefixes     = ["10.0.2.0/24"]
  service_endpoints    = ["Microsoft.Storage"]
  delegation {
    name = "fs"
    service_delegation {
      name = "Microsoft.DBforMySQL/flexibleServers"
      actions = [
        "Microsoft.Network/virtualNetworks/subnets/join/action",
      ]
    }
  }
}

resource "azurerm_private_dns_zone" "example" {
  name                = "example.mysql.database.azure.com"
  resource_group_name = azurerm_resource_group.example.name
}

resource "azurerm_private_dns_zone_virtual_network_link" "example" {
  name                  = "exampleVnetZone.com"
  private_dns_zone_name = azurerm_private_dns_zone.example.name
  virtual_network_id    = azurerm_virtual_network.example.id
  resource_group_name   = azurerm_resource_group.example.name
}

resource "azurerm_mysql_flexible_server" "example" {
  name                   = "example-fs"
  resource_group_name    = azurerm_resource_group.example.name
  location               = azurerm_resource_group.example.location
  administrator_login    = "psqladmin"
  administrator_password = "H@Sh1CoR3!"
  backup_retention_days  = 7
  delegated_subnet_id    = azurerm_subnet.example.id
  private_dns_zone_id    = azurerm_private_dns_zone.example.id
  sku_name               = "GP_Standard_D2ds_v4"

  storage {
    size_gb = 30 # attribute to change
  }

  depends_on = [azurerm_private_dns_zone_virtual_network_link.example]
}

Debug Output/Panic Output

N/A.

Expected Behaviour

When reducing storage.size_gb in configuration, the azurerm_mysql_flexible_server resource should be destroyed and re-created.

The same applies when auto-grow has increased the actual size_gb value, resulting in configuration drift.

Actual Behaviour

Terraform suggests an in-place update.

  # azurerm_mysql_flexible_server.example will be updated in-place
  ~ resource "azurerm_mysql_flexible_server" "main" {
      ~ storage {
          ~ size_gb            = 40 -> 30
        }
    }

Steps to Reproduce

1. terraform apply
2. Decrease storage.size_gb from 30 to 20.
3. terraform apply

Important Factoids

N/A.

References

Azure Database for MySQL - Flexible Server service tiers: Storage explicitly notes:

Storage can only be scaled up, not down.

[rcskosir]

Thank you for taking the time to open this issue. Please subscribe to PR #25074 created by @neil-yechenwei for this issue.

[github-actions]

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