Add validation for scratch disks in Instance Template

Signed-off-by: Modular Magician <magic-modules@google.com>

google/resource_compute_instance_template.go

@@ -5,6 +5,7 @@ import (
 	"reflect"
 
 	"github.com/hashicorp/errwrap"
+	"github.com/hashicorp/terraform/helper/customdiff"
 	"github.com/hashicorp/terraform/helper/resource"
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/helper/validation"
@@ -20,8 +21,11 @@ func resourceComputeInstanceTemplate() *schema.Resource {
 			State: schema.ImportStatePassthrough,
 		},
 		SchemaVersion: 1,
-		CustomizeDiff: resourceComputeInstanceTemplateSourceImageCustomizeDiff,
-		MigrateState:  resourceComputeInstanceTemplateMigrateState,
+		CustomizeDiff: customdiff.All(
+			resourceComputeInstanceTemplateSourceImageCustomizeDiff,
+			resourceComputeInstanceTemplateScratchDiskCustomizeDiff,
+		),
+		MigrateState: resourceComputeInstanceTemplateMigrateState,
 
 		// A compute instance template is more or less a subset of a compute
 		// instance. Please attempt to maintain consistency with the
@@ -541,6 +545,20 @@ func resourceComputeInstanceTemplateSourceImageCustomizeDiff(diff *schema.Resour
 	return nil
 }
 
+func resourceComputeInstanceTemplateScratchDiskCustomizeDiff(diff *schema.ResourceDiff, meta interface{}) error {
+	numDisks := diff.Get("disk.#").(int)
+	for i := 0; i < numDisks; i++ {
+		// misspelled on purpose, type is a special symbol
+		typee := diff.Get(fmt.Sprintf("disk.%d.type", i)).(string)
+		diskType := diff.Get(fmt.Sprintf("disk.%d.disk_type", i)).(string)
+		if typee == "SCRATCH" && diskType != "local-ssd" {
+			return fmt.Errorf("SCRATCH disks must have a disk_type of local-ssd. disk %d has disk_type %s", i, diskType)
+		}
+	}
+
+	return nil
+}
+
 func buildDisks(d *schema.ResourceData, config *Config) ([]*computeBeta.AttachedDisk, error) {
 	project, err := getProject(d, config)
 	if err != nil {

google/resource_compute_instance_template_test.go

@@ -736,6 +736,21 @@ func TestAccComputeInstanceTemplate_shieldedVmConfig2(t *testing.T) {
 	})
 }
 
+func TestAccComputeInstanceTemplate_invalidDiskType(t *testing.T) {
+	t.Parallel()
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		Steps: []resource.TestStep{
+			{
+				Config:      testAccComputeInstanceTemplate_invalidDiskType(),
+				ExpectError: regexp.MustCompile("SCRATCH disks must have a disk_type of local-ssd"),
+			},
+		},
+	})
+}
+
 func testAccCheckComputeInstanceTemplateDestroy(s *terraform.State) error {
 	config := testAccProvider.Meta().(*Config)
 
@@ -1868,3 +1883,40 @@ resource "google_compute_instance_template" "foobar" {
 	}
 }`, acctest.RandString(10), enableSecureBoot, enableVtpm, enableIntegrityMonitoring)
 }
+
+func testAccComputeInstanceTemplate_invalidDiskType() string {
+	return fmt.Sprintf(`
+data "google_compute_image" "my_image" {
+	family  = "centos-7"
+	project = "gce-uefi-images"
+}
+
+resource "google_compute_instance_template" "foobar" {
+	name = "instancet-test-%s"
+	machine_type = "n1-standard-1"
+	can_ip_forward = false
+
+	disk {
+		source_image = "${data.google_compute_image.my_image.self_link}"
+		auto_delete = true
+		boot = true
+	}
+
+	disk {
+		source_image = "${data.google_compute_image.my_image.self_link}"
+		auto_delete = true
+		type = "SCRATCH"
+		disk_type = "local-ssd"
+	}
+
+	disk {
+		source_image = "${data.google_compute_image.my_image.self_link}"
+		auto_delete = true
+		type = "SCRATCH"
+	}
+
+	network_interface {
+		network = "default"
+	}
+}`, acctest.RandString(10))
+}