Make target_pools optional

builtin/providers/google/resource_compute_instance_group_manager.go

@@ -55,7 +55,7 @@ func resourceComputeInstanceGroupManager() *schema.Resource {
 
 			"target_pools": &schema.Schema{
 				Type:     schema.TypeSet,
-				Required: true,
+				Optional: true,
 				Elem:     &schema.Schema{Type: schema.TypeString},
 				Set: func(v interface{}) int {
 					return hashcode.String(v.(string))

builtin/providers/google/resource_compute_instance_group_manager_test.go

@@ -23,6 +23,8 @@ func TestAccInstanceGroupManager_basic(t *testing.T) {
 				Check: resource.ComposeTestCheckFunc(
 					testAccCheckInstanceGroupManagerExists(
 						"google_compute_instance_group_manager.igm-basic", &manager),
+					testAccCheckInstanceGroupManagerExists(
+						"google_compute_instance_group_manager.igm-no-tp", &manager),
 				),
 			},
 		},
@@ -184,7 +186,17 @@ resource "google_compute_instance_group_manager" "igm-basic" {
 	base_instance_name = "igm-basic"
 	zone = "us-central1-c"
 	target_size = 2
-}`
+}
+
+resource "google_compute_instance_group_manager" "igm-no-tp" {
+	description = "Terraform test instance group manager"
+	name = "terraform-test-igm-no-tp"
+	instance_template = "${google_compute_instance_template.igm-basic.self_link}"
+	base_instance_name = "igm-no-tp"
+	zone = "us-central1-c"
+	target_size = 2
+}
+`
 
 const testAccInstanceGroupManager_update = `
 resource "google_compute_instance_template" "igm-update" {

website/source/docs/providers/google/r/compute_instance_group_manager.html.markdown

@@ -50,8 +50,8 @@ Supported characters include lowercase letters, numbers, and hyphens.
 * `target_size` - (Optional) If not given at creation time, this defaults to 1.  Do not specify this
   if you are managing the group with an autoscaler, as this will cause fighting.
 
-* `target_pools` - (Required) The full URL of all target pools to which new
-instances in the group are added. Updating the target pool values does not
+* `target_pools` - (Optional) The full URL of all target pools to which new
+instances in the group are added. Updating the target pools attribute does not
 affect existing instances.
 
 * `zone` - (Required) The zone that instances in this group should be created in.