AKS - allow in-place upgrade from free to paid sku_tier

azurerm/internal/services/containers/kubernetes_cluster_resource.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/Azure/azure-sdk-for-go/services/containerservice/mgmt/2020-03-01/containerservice"
+	"github.com/hashicorp/terraform-plugin-sdk/helper/customdiff"
 	"github.com/hashicorp/terraform-plugin-sdk/helper/schema"
 	"github.com/hashicorp/terraform-plugin-sdk/helper/validation"
 	"github.com/terraform-providers/terraform-provider-azurerm/azurerm/helpers/azure"
@@ -38,6 +39,13 @@ func resourceArmKubernetesCluster() *schema.Resource {
 			return err
 		}),
 
+		CustomizeDiff: customdiff.Sequence(
+			// Downgrade from Paid to Free is not supported and requires rebuild to apply
+			customdiff.ForceNewIfChange("sku_tier", func(old, new, meta interface{}) bool {
+				return new == "Free"
+			}),
+		),
+
 		Timeouts: &schema.ResourceTimeout{
 			Create: schema.DefaultTimeout(90 * time.Minute),
 			Read:   schema.DefaultTimeout(5 * time.Minute),
@@ -510,11 +518,11 @@ func resourceArmKubernetesCluster() *schema.Resource {
 				Type:     schema.TypeString,
 				Optional: true,
 				// @tombuildsstuff (2020-05-29) - Preview limitations:
-				//  * Currently, cannot convert as existing cluster to enable the Uptime SLA.
 				//  * Currently, there is no way to remove Uptime SLA from an AKS cluster after creation with it enabled.
 				//  * Private clusters aren't currently supported.
-				ForceNew: true,
-				Default:  string(containerservice.Free),
+				// @jackofallops (2020-07-21) - Update:
+				//  * sku_tier can now be upgraded in place, downgrade requires rebuild
+				Default: string(containerservice.Free),
 				ValidateFunc: validation.StringInSlice([]string{
 					string(containerservice.Free),
 					string(containerservice.Paid),
@@ -1032,6 +1040,11 @@ func resourceArmKubernetesClusterUpdate(d *schema.ResourceData, meta interface{}
 		existing.Identity = expandKubernetesClusterManagedClusterIdentity(managedClusterIdentityRaw)
 	}
 
+	if d.HasChange("sku_tier") {
+		updateCluster = true
+		existing.Sku.Tier = containerservice.ManagedClusterSKUTier(d.Get("sku_tier").(string))
+	}
+
 	if updateCluster {
 		log.Printf("[DEBUG] Updating the Kubernetes Cluster %q (Resource Group %q)..", id.Name, id.ResourceGroup)
 		future, err := clusterClient.CreateOrUpdate(ctx, id.ResourceGroup, id.Name, existing)

azurerm/internal/services/containers/tests/kubernetes_cluster_other_resource_test.go

@@ -327,6 +327,37 @@ func testAccAzureRMKubernetesCluster_nodeResourceGroup(t *testing.T) {
 	})
 }
 
+func TestAccAzureRMKubernetesCluster_upgradeSkuTier(t *testing.T) {
+	checkIfShouldRunTestsIndividually(t)
+	testAccAzureRMKubernetesCluster_upgradeSkuTier(t)
+}
+
+func testAccAzureRMKubernetesCluster_upgradeSkuTier(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_kubernetes_cluster", "test")
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { acceptance.PreCheck(t) },
+		Providers:    acceptance.SupportedProviders,
+		CheckDestroy: testCheckAzureRMKubernetesClusterDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAzureRMKubernetesCluster_freeSkuConfig(data),
+				Check: resource.ComposeTestCheckFunc(
+					testCheckAzureRMKubernetesClusterExists(data.ResourceName),
+				),
+			},
+			data.ImportStep(),
+			{
+				Config: testAccAzureRMKubernetesCluster_paidSkuConfig(data),
+				Check: resource.ComposeTestCheckFunc(
+					testCheckAzureRMKubernetesClusterExists(data.ResourceName),
+				),
+			},
+			data.ImportStep(),
+		},
+	})
+}
+
 func TestAccAzureRMKubernetesCluster_paidSku(t *testing.T) {
 	checkIfShouldRunTestsIndividually(t)
 	testAccAzureRMKubernetesCluster_paidSku(t)
@@ -862,6 +893,39 @@ resource "azurerm_kubernetes_cluster" "test" {
 `, data.RandomInteger, location, data.RandomInteger, data.RandomInteger)
 }
 
+func testAccAzureRMKubernetesCluster_freeSkuConfig(data acceptance.TestData) string {
+	// @tombuildsstuff (2020-05-29) - this is only supported in a handful of regions
+	// 								  whilst in Preview - hard-coding for now
+	location := "westus2" // TODO: data.Locations.Primary
+	return fmt.Sprintf(`
+provider "azurerm" {
+  features {}
+}
+
+resource "azurerm_resource_group" "test" {
+  name     = "acctestRG-aks-%d"
+  location = "%s"
+}
+
+resource "azurerm_kubernetes_cluster" "test" {
+  name                = "acctestaks%d"
+  location            = azurerm_resource_group.test.location
+  resource_group_name = azurerm_resource_group.test.name
+  dns_prefix          = "acctestaks%d"
+
+  default_node_pool {
+    name       = "default"
+    node_count = 1
+    vm_size    = "Standard_DS2_v2"
+  }
+
+  identity {
+    type = "SystemAssigned"
+  }
+}
+`, data.RandomInteger, location, data.RandomInteger, data.RandomInteger)
+}
+
 func testAccAzureRMKubernetesCluster_tagsConfig(data acceptance.TestData) string {
 	return fmt.Sprintf(`
 provider "azurerm" {

website/docs/r/kubernetes_cluster.html.markdown

@@ -110,9 +110,9 @@ In addition, one of either `identity` or `service_principal` blocks must be spec
 
 -> **NOTE:** One of either `identity` or `service_principal` must be specified.
 
-* `sku_tier` - (Optional) The SKU Tier that should be used for this Kubernetes Cluster. Changing this forces a new resource to be created. Possible values are `Free` and `Paid` (which includes the Uptime SLA). Defaults to `Free`.
+* `sku_tier` - (Optional) The SKU Tier that should be used for this Kubernetes Cluster. Possible values are `Free` and `Paid` (which includes the Uptime SLA). Defaults to `Free`.
 
-~> **Note:** This functionality is in Preview and has [several limitations](https://docs.microsoft.com/en-us/azure/aks/uptime-sla).
+~> **Note:**  It is currently possible to upgrade in place from `Free` to `Paid`. However, changing this value from `Paid` to `Free` will force a new resource to be created.
 
 * `tags` - (Optional) A mapping of tags to assign to the resource.