r\linux_virtual_machine,r\windows_virtual_machine: Add support for diff_disk_settings.placement

internal/services/compute/linux_virtual_machine_resource.go

@@ -386,7 +386,10 @@ func resourceLinuxVirtualMachineCreate(d *pluginsdk.ResourceData, meta interface
 	networkInterfaceIds := expandVirtualMachineNetworkInterfaceIDs(networkInterfaceIdsRaw)
 
 	osDiskRaw := d.Get("os_disk").([]interface{})
-	osDisk := expandVirtualMachineOSDisk(osDiskRaw, compute.OperatingSystemTypesLinux)
+	osDisk, err := expandVirtualMachineOSDisk(osDiskRaw, compute.OperatingSystemTypesLinux)
+	if err != nil {
+		return fmt.Errorf("expanding `os_disk`: %+v", err)
+	}
 
 	secretsRaw := d.Get("secret").([]interface{})
 	secrets := expandLinuxSecrets(secretsRaw)
@@ -948,7 +951,11 @@ func resourceLinuxVirtualMachineUpdate(d *pluginsdk.ResourceData, meta interface
 		shouldDeallocate = true
 
 		osDiskRaw := d.Get("os_disk").([]interface{})
-		osDisk := expandVirtualMachineOSDisk(osDiskRaw, compute.OperatingSystemTypesLinux)
+		osDisk, err := expandVirtualMachineOSDisk(osDiskRaw, compute.OperatingSystemTypesLinux)
+		if err != nil {
+			return fmt.Errorf("expanding `os_disk`: %+v", err)
+		}
+
 		update.VirtualMachineProperties.StorageProfile = &compute.StorageProfile{
 			OsDisk: osDisk,
 		}

internal/services/compute/linux_virtual_machine_resource_disk_os_test.go

@@ -141,13 +141,28 @@ func TestAccLinuxVirtualMachine_diskOSDiskEncryptionSetUpdate(t *testing.T) {
 	})
 }
 
-func TestAccLinuxVirtualMachine_diskOSEphemeral(t *testing.T) {
+func TestAccLinuxVirtualMachine_diskOSEphemeralDefault(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_linux_virtual_machine", "test")
 	r := LinuxVirtualMachineResource{}
 
 	data.ResourceTest(t, r, []acceptance.TestStep{
 		{
-			Config: r.diskOSEphemeral(data),
+			Config: r.diskOSEphemeralDefault(data),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep(),
+	})
+}
+
+func TestAccLinuxVirtualMachine_diskOSEphemeralResourceDisk(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_linux_virtual_machine", "test")
+	r := LinuxVirtualMachineResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.diskOSEphemeralResourceDisk(data),
 			Check: acceptance.ComposeTestCheckFunc(
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
@@ -625,7 +640,7 @@ resource "azurerm_linux_virtual_machine" "test" {
 `, r.diskOSDiskDiskEncryptionSetResource(data), data.RandomInteger)
 }
 
-func (r LinuxVirtualMachineResource) diskOSEphemeral(data acceptance.TestData) string {
+func (r LinuxVirtualMachineResource) diskOSEphemeralDefault(data acceptance.TestData) string {
 	return fmt.Sprintf(`
 %s
 
@@ -663,6 +678,45 @@ resource "azurerm_linux_virtual_machine" "test" {
 `, r.template(data), data.RandomInteger)
 }
 
+func (r LinuxVirtualMachineResource) diskOSEphemeralResourceDisk(data acceptance.TestData) string {
+	return fmt.Sprintf(`
+%s
+
+resource "azurerm_linux_virtual_machine" "test" {
+  name                = "acctestVM-%d"
+  resource_group_name = azurerm_resource_group.test.name
+  location            = azurerm_resource_group.test.location
+  size                = "Standard_F4s_v2"
+  admin_username      = "adminuser"
+  network_interface_ids = [
+    azurerm_network_interface.test.id,
+  ]
+
+  admin_ssh_key {
+    username   = "adminuser"
+    public_key = local.first_public_key
+  }
+
+  os_disk {
+    caching              = "ReadOnly"
+    storage_account_type = "Standard_LRS"
+
+    diff_disk_settings {
+      option    = "Local"
+      placement = "ResourceDisk"
+    }
+  }
+
+  source_image_reference {
+    publisher = "Canonical"
+    offer     = "UbuntuServer"
+    sku       = "16.04-LTS"
+    version   = "latest"
+  }
+}
+`, r.template(data), data.RandomInteger)
+}
+
 func (r LinuxVirtualMachineResource) diskOSStorageAccountType(data acceptance.TestData, accountType string) string {
 	return fmt.Sprintf(`
 %s

internal/services/compute/virtual_machine.go

@@ -2,6 +2,7 @@ package compute
 
 import (
 	"context"
+	"fmt"
 
 	"github.com/Azure/azure-sdk-for-go/services/compute/mgmt/2021-07-01/compute"
 	"github.com/hashicorp/terraform-provider-azurerm/internal/identity"
@@ -200,6 +201,16 @@ func virtualMachineOSDiskSchema() *pluginsdk.Schema {
 									string(compute.DiffDiskOptionsLocal),
 								}, false),
 							},
+							"placement": {
+								Type:     pluginsdk.TypeString,
+								Optional: true,
+								ForceNew: true,
+								Default:  string(compute.DiffDiskPlacementCacheDisk),
+								ValidateFunc: validation.StringInSlice([]string{
+									string(compute.DiffDiskPlacementCacheDisk),
+									string(compute.DiffDiskPlacementResourceDisk),
+								}, false),
+							},
 						},
 					},
 				},
@@ -236,10 +247,11 @@ func virtualMachineOSDiskSchema() *pluginsdk.Schema {
 	}
 }
 
-func expandVirtualMachineOSDisk(input []interface{}, osType compute.OperatingSystemTypes) *compute.OSDisk {
+func expandVirtualMachineOSDisk(input []interface{}, osType compute.OperatingSystemTypes) (*compute.OSDisk, error) {
 	raw := input[0].(map[string]interface{})
+	caching := raw["caching"].(string)
 	disk := compute.OSDisk{
-		Caching: compute.CachingTypes(raw["caching"].(string)),
+		Caching: compute.CachingTypes(caching),
 		ManagedDisk: &compute.ManagedDiskParameters{
 			StorageAccountType: compute.StorageAccountTypes(raw["storage_account_type"].(string)),
 		},
@@ -258,9 +270,15 @@ func expandVirtualMachineOSDisk(input []interface{}, osType compute.OperatingSys
 	}
 
 	if diffDiskSettingsRaw := raw["diff_disk_settings"].([]interface{}); len(diffDiskSettingsRaw) > 0 {
+		if caching != string(compute.CachingTypesReadOnly) {
+			// Restriction per https://docs.microsoft.com/azure/virtual-machines/ephemeral-os-disks-deploy#vm-template-deployment
+			return nil, fmt.Errorf("`diff_disk_settings` can only be set when `caching` is set to `ReadOnly`")
+		}
+
 		diffDiskRaw := diffDiskSettingsRaw[0].(map[string]interface{})
 		disk.DiffDiskSettings = &compute.DiffDiskSettings{
-			Option: compute.DiffDiskOptions(diffDiskRaw["option"].(string)),
+			Option:    compute.DiffDiskOptions(diffDiskRaw["option"].(string)),
+			Placement: compute.DiffDiskPlacement(diffDiskRaw["placement"].(string)),
 		}
 	}
 
@@ -274,7 +292,7 @@ func expandVirtualMachineOSDisk(input []interface{}, osType compute.OperatingSys
 		disk.Name = utils.String(name)
 	}
 
-	return &disk
+	return &disk, nil
 }
 
 func flattenVirtualMachineOSDisk(ctx context.Context, disksClient *compute.DisksClient, input *compute.OSDisk) ([]interface{}, error) {
@@ -284,8 +302,14 @@ func flattenVirtualMachineOSDisk(ctx context.Context, disksClient *compute.Disks
 
 	diffDiskSettings := make([]interface{}, 0)
 	if input.DiffDiskSettings != nil {
+		placement := string(compute.DiffDiskPlacementCacheDisk)
+		if input.DiffDiskSettings.Placement != "" {
+			placement = string(input.DiffDiskSettings.Placement)
+		}
+
 		diffDiskSettings = append(diffDiskSettings, map[string]interface{}{
-			"option": string(input.DiffDiskSettings.Option),
+			"option":    string(input.DiffDiskSettings.Option),
+			"placement": placement,
 		})
 	}
 

internal/services/compute/windows_virtual_machine_resource.go

@@ -409,7 +409,10 @@ func resourceWindowsVirtualMachineCreate(d *pluginsdk.ResourceData, meta interfa
 	networkInterfaceIds := expandVirtualMachineNetworkInterfaceIDs(networkInterfaceIdsRaw)
 
 	osDiskRaw := d.Get("os_disk").([]interface{})
-	osDisk := expandVirtualMachineOSDisk(osDiskRaw, compute.OperatingSystemTypesWindows)
+	osDisk, err := expandVirtualMachineOSDisk(osDiskRaw, compute.OperatingSystemTypesWindows)
+	if err != nil {
+		return fmt.Errorf("expanding `os_disk`: %+v", err)
+	}
 
 	secretsRaw := d.Get("secret").([]interface{})
 	secrets := expandWindowsSecrets(secretsRaw)
@@ -996,7 +999,11 @@ func resourceWindowsVirtualMachineUpdate(d *pluginsdk.ResourceData, meta interfa
 		shouldDeallocate = true
 
 		osDiskRaw := d.Get("os_disk").([]interface{})
-		osDisk := expandVirtualMachineOSDisk(osDiskRaw, compute.OperatingSystemTypesWindows)
+		osDisk, err := expandVirtualMachineOSDisk(osDiskRaw, compute.OperatingSystemTypesWindows)
+		if err != nil {
+			return fmt.Errorf("expanding `os_disk`: %+v", err)
+		}
+
 		update.VirtualMachineProperties.StorageProfile = &compute.StorageProfile{
 			OsDisk: osDisk,
 		}

internal/services/compute/windows_virtual_machine_resource_disk_os_test.go

@@ -141,13 +141,28 @@ func TestAccWindowsVirtualMachine_diskOSDiskEncryptionSetUpdate(t *testing.T) {
 	})
 }
 
-func TestAccWindowsVirtualMachine_diskOSEphemeral(t *testing.T) {
+func TestAccWindowsVirtualMachine_diskOSEphemeralDefault(t *testing.T) {
 	data := acceptance.BuildTestData(t, "azurerm_windows_virtual_machine", "test")
 	r := WindowsVirtualMachineResource{}
 
 	data.ResourceTest(t, r, []acceptance.TestStep{
 		{
-			Config: r.diskOSEphemeral(data),
+			Config: r.diskOSEphemeralDefault(data),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep("admin_password"),
+	})
+}
+
+func TestAccWindowsVirtualMachine_diskOSEphemeralResourceDisk(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_windows_virtual_machine", "test")
+	r := WindowsVirtualMachineResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.diskOSEphemeralResourceDisk(data),
 			Check: acceptance.ComposeTestCheckFunc(
 				check.That(data.ResourceName).ExistsInAzure(r),
 			),
@@ -599,7 +614,7 @@ resource "azurerm_windows_virtual_machine" "test" {
 `, r.diskOSDiskDiskEncryptionSetResource(data))
 }
 
-func (r WindowsVirtualMachineResource) diskOSEphemeral(data acceptance.TestData) string {
+func (r WindowsVirtualMachineResource) diskOSEphemeralDefault(data acceptance.TestData) string {
 	return fmt.Sprintf(`
 %s
 
@@ -634,6 +649,42 @@ resource "azurerm_windows_virtual_machine" "test" {
 `, r.template(data))
 }
 
+func (r WindowsVirtualMachineResource) diskOSEphemeralResourceDisk(data acceptance.TestData) string {
+	return fmt.Sprintf(`
+%s
+
+resource "azurerm_windows_virtual_machine" "test" {
+  name                = local.vm_name
+  resource_group_name = azurerm_resource_group.test.name
+  location            = azurerm_resource_group.test.location
+  # Message="OS disk of Ephemeral VM with size greater than 32 GB is not allowed for VM size Standard_F2s_v2"
+  size           = "Standard_DS4_v2"
+  admin_username = "adminuser"
+  admin_password = "P@$$w0rd1234!"
+  network_interface_ids = [
+    azurerm_network_interface.test.id,
+  ]
+
+  os_disk {
+    caching              = "ReadOnly"
+    storage_account_type = "Standard_LRS"
+
+    diff_disk_settings {
+      option    = "Local"
+      placement = "ResourceDisk"
+    }
+  }
+
+  source_image_reference {
+    publisher = "MicrosoftWindowsServer"
+    offer     = "WindowsServer"
+    sku       = "2022-datacenter-smalldisk"
+    version   = "latest"
+  }
+}
+`, r.template(data))
+}
+
 func (r WindowsVirtualMachineResource) diskOSStorageAccountType(data acceptance.TestData, accountType string) string {
 	return fmt.Sprintf(`
 %s

website/docs/r/linux_virtual_machine.html.markdown

@@ -230,6 +230,8 @@ A `diff_disk_settings` block supports the following:
 
 * `option` - (Required) Specifies the Ephemeral Disk Settings for the OS Disk. At this time the only possible value is `Local`. Changing this forces a new resource to be created.
 
+* `placement` - (Optional) Specifies where to store the Ephemeral Disk. Possible values are `CacheDisk` and `ResourceDisk`. Defaults to `CacheDisk`. Changing this forces a new resource to be created.
+
 ---
 
 A `identity` block supports the following:
@@ -248,7 +250,9 @@ A `os_disk` block supports the following:
 
 * `storage_account_type` - (Required) The Type of Storage Account which should back this the Internal OS Disk. Possible values are `Standard_LRS`, `StandardSSD_LRS` and `Premium_LRS`. Changing this forces a new resource to be created.
 
-* `diff_disk_settings` (Optional) A `diff_disk_settings` block as defined above.
+* `diff_disk_settings` (Optional) A `diff_disk_settings` block as defined above. Changing this forces a new resource to be created.
+
+-> **NOTE:** `diff_disk_settings` can only be set when `caching` is set to `ReadOnly`. More information can be found [here](https://docs.microsoft.com/azure/virtual-machines/ephemeral-os-disks-deploy#vm-template-deployment)
 
 * `disk_encryption_set_id` - (Optional) The ID of the Disk Encryption Set which should be used to Encrypt this OS Disk.
 

website/docs/r/windows_virtual_machine.html.markdown

@@ -221,6 +221,8 @@ A `diff_disk_settings` block supports the following:
 
 * `option` - (Required) Specifies the Ephemeral Disk Settings for the OS Disk. At this time the only possible value is `Local`. Changing this forces a new resource to be created.
 
+* `placement` - (Optional) Specifies where to store the Ephemeral Disk. Possible values are `CacheDisk` and `ResourceDisk`. Defaults to `CacheDisk`. Changing this forces a new resource to be created.
+
 ---
 
 A `identity` block supports the following:
@@ -239,7 +241,9 @@ A `os_disk` block supports the following:
 
 * `storage_account_type` - (Required) The Type of Storage Account which should back this the Internal OS Disk. Possible values are `Standard_LRS`, `StandardSSD_LRS` and `Premium_LRS`. Changing this forces a new resource to be created.
 
-* `diff_disk_settings` (Optional) A `diff_disk_settings` block as defined above.
+* `diff_disk_settings` (Optional) A `diff_disk_settings` block as defined above. Changing this forces a new resource to be created.
+
+-> **NOTE:** `diff_disk_settings` can only be set when `caching` is set to `ReadOnly`. More information can be found [here](https://docs.microsoft.com/azure/virtual-machines/ephemeral-os-disks-deploy#vm-template-deployment)
 
 * `disk_encryption_set_id` - (Optional) The ID of the Disk Encryption Set which should be used to Encrypt this OS Disk.