Undesired cluster version change is detected during plan phase causing pods to be evicted during apply

[cveld]

Is there an existing issue for this?

• I have searched the existing issues

Community Note

• Please vote on this issue by adding a 👍 reaction to the original issue to help the community and maintainers prioritize this request
• Please do not leave "+1" or "me too" comments, they generate extra noise for issue followers and do not help prioritize the request
• If you are interested in working on this issue or have submitted a pull request, please leave a comment

Terraform Version

1.3.6

AzureRM Provider Version

3.48

Affected Resource(s)/Data Source(s)

azurerm_kubernetes_cluster

Terraform Configuration Files

Using the aks resource indirectly through the following module:

module "aks" {
  source  = "Azure/aks/azurerm"
  version = "6.7.1"

  #prefix                    = "prefix-${random_id.prefix.hex}"
  prefix                    = "sandbox"
  resource_group_name       = var.resource_group_name
  kubernetes_version        = "1.24" # don't specify the patch version!
  automatic_channel_upgrade = "patch"
  network_plugin  = "azure"
  network_policy  = "azure"
  os_disk_size_gb = 60
  sku_tier        = "Paid"
  rbac_aad        = false
  vnet_subnet_id          = azurerm_subnet.aks.id
  log_analytics_workspace = azurerm_log_analytics_workspace.log_analytics_workspace
  agents_max_pods         = 100
}

Debug Output/Panic Output

N/A

Expected Behaviour

AKS should not report a change

Actual Behaviour

AKS reports a change. 1.24.9 -> 1.24

I ran az aks list -o table and interestingly the KubernetesVersion property got updated to 1.24.9!

Name                Location    ResourceGroup    KubernetesVersion    CurrentKubernetesVersion    ProvisioningState    Fqdn
------------------  ----------  ---------------  -------------------  --------------------------  -------------------  ------------------------------------------------
sandbox-aks         westeurope  rg-test          1.24.9               1.24.9                      Succeeded            sandbox-redacted.hcp.westeurope.azmk8s.io

Steps to Reproduce

1. terraform plan
2. terraform apply

Important Factoids

No response

References

Reported the issue originally downstream in the module repo: Azure/terraform-azurerm-aks#329