Added an option to have 0 in disk_size_gb property of managed_disk

azurerm/resource_arm_managed_disk.go

@@ -86,6 +86,7 @@ func resourceArmManagedDisk() *schema.Resource {
 			"disk_size_gb": {
 				Type:         schema.TypeInt,
 				Optional:     true,
+				Computed:     true,
 				ValidateFunc: validateDiskSizeGB,
 			},
 
@@ -98,9 +99,9 @@ func resourceArmManagedDisk() *schema.Resource {
 
 func validateDiskSizeGB(v interface{}, k string) (ws []string, errors []error) {
 	value := v.(int)
-	if value < 1 || value > 4095 {
+	if value < 0 || value > 4095 {
 		errors = append(errors, fmt.Errorf(
-			"The `disk_size_gb` can only be between 1 and 4095"))
+			"The `disk_size_gb` can only be between 0 and 4095"))
 	}
 	return
 }

azurerm/resource_arm_managed_disk_test.go

@@ -30,6 +30,25 @@ func TestAccAzureRMManagedDisk_empty(t *testing.T) {
 	})
 }
 
+func TestAccAzureRMManagedDisk_zeroGbFromPlatformImage(t *testing.T) {
+	var d compute.Disk
+	ri := acctest.RandInt()
+	config := testAccAzureRMManagedDisk_zeroGbFromPlatformImage(ri, testLocation())
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testCheckAzureRMManagedDiskDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: config,
+				Check: resource.ComposeTestCheckFunc(
+					testCheckAzureRMManagedDiskExists("azurerm_managed_disk.test", &d, true),
+				),
+			},
+		},
+	})
+}
+
 func TestAccAzureRMManagedDisk_import(t *testing.T) {
 	var d compute.Disk
 	var vm compute.VirtualMachine
@@ -451,6 +470,32 @@ resource "azurerm_managed_disk" "test" {
 `, location, rInt, location, rInt)
 }
 
+func testAccAzureRMManagedDisk_zeroGbFromPlatformImage(rInt int, location string) string {
+	return fmt.Sprintf(`
+data "azurerm_platform_image" "test" {
+  location  = "%s"
+  publisher = "Canonical"
+  offer     = "UbuntuServer"
+  sku       = "16.04-LTS"
+}
+
+resource "azurerm_resource_group" "test" {
+  name = "acctestRG-%d"
+  location = "%s"
+}
+resource "azurerm_managed_disk" "test" {
+  name = "acctestd-%d"
+  location = "${azurerm_resource_group.test.location}"
+  resource_group_name = "${azurerm_resource_group.test.name}"
+  os_type = "Linux"
+  create_option = "FromImage"
+  disk_size_gb = "0" 
+  image_reference_id = "${data.azurerm_platform_image.test.id}"
+  storage_account_type = "Standard_LRS"
+}
+`, location, rInt, location, rInt)
+}
+
 func testAccAzureRMManagedDisk_encryption(rInt int, rString string, location string) string {
 	return fmt.Sprintf(`
 data "azurerm_client_config" "current" {}