Undocumented breaking change in 4.x with azurerm_kusto_cluster language_extensions

[Costo]

Is there an existing issue for this?

• I have searched the existing issues

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Terraform Version

1.9.4

AzureRM Provider Version

4.4.0

Affected Resource(s)/Data Source(s)

azurerm_kusto_cluster

Terraform Configuration Files

resource "azurerm_kusto_cluster" "cluster" {
  name                = "kustocluster"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name

  language_extensions {
      name  = "PYTHON"
      image = "Python3_6_5"
  }

  sku {
    name     = "Standard_D13_v2"
    capacity = 2
  }
}

Debug Output/Panic Output

2024-10-07T21:07:37.3981446Z 2024-10-07T21:07:37.395Z [DEBUG] ReferenceTransformer: "azurerm_kusto_cluster.cluster" references: []
2024-10-07T21:07:37.3982371Z 2024-10-07T21:07:37.396Z [DEBUG] UpgradeResourceState: attribute "engine" no longer present in schema
2024-10-07T21:07:37.3983882Z 2024-10-07T21:07:37.396Z [ERROR] provider.terraform-provider-azurerm_v4.4.0_x5.exe: Response contains error diagnostic: tf_req_id=2486e30f-1f3a-6b21-5d25-96b6b60dc5f6 @caller=github.com/hashicorp/terraform-plugin-go@v0.23.0/tfprotov5/internal/diag/diagnostics.go:58 diagnostic_attribute="AttributeName(\"language_extensions\").ElementKeyInt(0)" diagnostic_detail="" diagnostic_summary="missing expected {" tf_provider_addr=registry.terraform.io/hashicorp/azurerm tf_resource_type=azurerm_kusto_cluster tf_rpc=UpgradeResourceState @module=sdk.proto diagnostic_severity=ERROR tf_proto_version=5.6 timestamp=2024-10-07T21:07:37.396Z
2024-10-07T21:07:37.3984931Z 2024-10-07T21:07:37.397Z [ERROR] vertex "azurerm_kusto_cluster.cluster" error: missing expected {
2024-10-07T21:07:37.3985501Z 2024-10-07T21:07:37.397Z [ERROR] vertex "azurerm_kusto_cluster.cluster (expand)" error: missing expected {

...

╷
│ Error: missing expected {
│ 
│   with azurerm_kusto_cluster.cluster,
│   on kusto.tf line 1, in resource "azurerm_kusto_cluster" "cluster":
│    1: resource "azurerm_kusto_cluster" "cluster" {
│ 
╵
##[error]Error: Terraform Plan failed with exit code: 1

Expected Behaviour

Terraform plan should succeed

Actual Behaviour

Terraform plan fails with error

│ Error: missing expected {
│ 
│   with azurerm_kusto_cluster.cluster,
│   on kusto.tf line 1, in resource "azurerm_kusto_cluster" "cluster":
│    1: resource "azurerm_kusto_cluster" "cluster" {
│ 

Steps to Reproduce

Upgrading from AzureRM 3.61.0 to 4.4.0, the language_extensions block changed from:

language_extensions = ["PYTHON"]

to:

language_extensions {
      name  = "PYTHON"
      image = "Python3_6_5"
}

But this change is incompatible with existing state and terraform plan fails after loading state.

This change was introduced by this PR: #21961
The new block name was supposed to be language_extension singular, but the name remained language_extensions plural.

Important Factoids

No response

References

No response

[liuwuliuyun]

Hi @Costo , thanks for bring this to our attention, I will work on a PR to fix this issue and keep you updated in this thread.