azurerm_postgresql_flexible_server - move the error check for storage_mb from CustomizeDiff to Create/Update func

[neil-yechenwei]

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Description

I run tf apply against below tf config 1 and the resources are created successfully. Then I update name of azurerm_postgresql_flexible_server and change storage_mb from 65536 to 32768 like below tf config 2 and run tf apply again. I expect that TF would re-create the resource successfully but it failed with below error. What is happening is that the validation in the customized diff is catching the error because the validation doesn't know that it is going to be destroyed and re-created. So this error check would always check if new storage_mb is lower than old storage_mb. Hence, we have to move the error check for storage_mb from CustomizeDiff to Create/Update func.

Error Message:

Planning failed. Terraform encountered an error while generating this plan.
╷
│ Error: 1 error occurred:
│       * 'storage_mb' can only be scaled up, expected the new 'storage_mb' value (32768) to be larger than the previous 'storage_mb' value (65536)
│
│
│
│   with azurerm_postgresql_flexible_server.test,
│   on main.tf line 23, in resource "azurerm_postgresql_flexible_server" "test":
│   23: resource "azurerm_postgresql_flexible_server" "test" {

The tf config 1 for the first apply:

provider "azurerm" {
  features {}
}
 
resource "azurerm_resource_group" "test" {
  name     = "acctestRG-postgresql-test01373"
  location = "eastus"
}
 
resource "azurerm_postgresql_flexible_server" "test" {
  name                   = "acctest-fs-test01373"
  resource_group_name    = azurerm_resource_group.test.name
  location               = azurerm_resource_group.test.location
  administrator_login    = "adminTerraform"
  administrator_password = "QAZwsx123"
  sku_name               = "GP_Standard_D2s_v3"
  version                = "12"
  zone                   = 2
  storage_tier           = "P6"
  storage_mb             = 65536
}

The tf config 2 for the second apply:

provider "azurerm" {
  features {}
}
 
resource "azurerm_resource_group" "test" {
  name     = "acctestRG-postgresql-test01373"
  location = "eastus"
}
 
resource "azurerm_postgresql_flexible_server" "test" {
  name                   = "acctest-newfs-test01373"
  resource_group_name    = azurerm_resource_group.test.name
  location               = azurerm_resource_group.test.location
  administrator_login    = "adminTerraform"
  administrator_password = "QAZwsx123"
  sku_name               = "GP_Standard_D2s_v3"
  version                = "12"
  zone                   = 2
  storage_tier           = "P6"
  storage_mb             = 32768
}

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• azurerm_postgresql_flexible_server - move the error check for storage_mb from CustomizeDiff to Create/Update func

This is a (please select all that apply):

• Bug Fix
• New Feature (ie adding a service, resource, or data source)
• Enhancement
• Breaking Change

Note

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[katbyte]

is it not possible to also detect that something has changed forcing a new resoruce to be created and just not throw the error?

[neil-yechenwei]

@katbyte , Unfortunately, I didn't find any way to ask terraform if the resource is going to be destroyed or not, I assume that bit is only known by the core runtime. And I didn't find any way to judge if the resource is going to be destroyed per the condition combination. So I have to move it to create/update func.

[katbyte]

👍

[neil-yechenwei]

@katbyte , thanks for the comment. Please take another look.

[katbyte]

LGTM 🌻

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