Add example and test to showcase count increase/decrease for backend service

mmv1/products/compute/RegionBackendService.yaml

@@ -18,6 +18,9 @@ kind: 'compute#backendService'
 description: |
   A Region Backend Service defines a regionally-scoped group of virtual
   machines that will serve traffic for load balancing.
+
+  ~> **Note:** Recreating a `google_compute_region_backend_service` that references other dependant resources like `google_compute_instance_group` will give a `resourceInUseByAnotherResource` error.
+  Use `lifecycle.create_before_destroy` on this other resources to avoid this type of error as shown in the Dynamic Backend Count example.
 references:
   guides:
     'Internal TCP/UDP Load Balancing': 'https://cloud.google.com/compute/docs/load-balancing/internal/'
@@ -128,6 +131,14 @@ examples:
       default_neg_name: 'network-endpoint'
       health_check_name: 'rbs-health-check'
       network_name: 'network'
+  - name: 'region_backend_service_dynamic_backend_count'
+    primary_resource_id: 'default'
+    vars:
+      region_backend_service_name: 'region-service'
+      health_check_name: 'health-check'
+      instance_group_name: 'instance_group'
+      network_name: 'network'
+    exclude_test: true
 parameters:
   - name: 'region'
     type: ResourceRef

mmv1/templates/terraform/examples/region_backend_service_dynamic_backend_count.tf.tmpl

@@ -0,0 +1,43 @@
+locals {
+  zones           = ["europe-west1-b", "europe-west1-c", "europe-west1-d"]
+  s1_count        = 3
+}
+
+resource "google_compute_network" "network" {
+  name    = "{{index $.Vars "network_name"}}"
+}
+
+resource "google_compute_region_backend_service" "default" {
+  name = "{{index $.Vars "region_backend_service_name"}}"
+  region = "europe-west1"
+
+  dynamic "backend" {
+    for_each = google_compute_instance_group.s1
+    content {
+      balancing_mode = "CONNECTION"
+      group = backend.value.self_link
+    }
+  }
+
+  health_checks = [
+    google_compute_health_check.default.self_link,
+  ]
+}
+
+resource "google_compute_health_check" "default" {
+  name = "{{index $.Vars "health_check_name"}}"
+  tcp_health_check {
+    port = "80"
+  }
+}
+
+resource "google_compute_instance_group" "s1" {
+  count   = local.s1_count
+  name    = "{{index $.Vars "instance_group_name"}}-${count.index}"
+  zone    = element(local.zones, count.index)
+  network = google_compute_network.network.self_link
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}

mmv1/third_party/terraform/services/compute/resource_compute_region_backend_service_test.go.tmpl

@@ -421,6 +421,145 @@ func TestAccComputeRegionBackendService_withLogConfig(t *testing.T) {
 	})
 }
 
+func TestAccComputeRegionBackendService_withDynamicBackendCount(t *testing.T) {
+	t.Parallel()
+
+	randString := acctest.RandString(t, 10)
+
+	serviceName := fmt.Sprintf("tf-test-%s", randString)
+	checkName := fmt.Sprintf("tf-test-%s", randString)
+	netName := fmt.Sprintf("tf-test-%s", randString)
+	igName := fmt.Sprintf("tf-test-%s", randString)
+
+	acctest.VcrTest(t, resource.TestCase{
+		PreCheck:                 func() { acctest.AccTestPreCheck(t) },
+		ProtoV5ProviderFactories: acctest.ProtoV5ProviderFactories(t),
+		CheckDestroy:             testAccCheckComputeRegionBackendServiceDestroyProducer(t),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccComputeRegionBackendService_withDynamicBackendCount(serviceName, netName, checkName, igName),
+			},
+			{
+				ResourceName:      "google_compute_region_backend_service.foobar",
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+			{
+				Config: testAccComputeRegionBackendService_withDynamicBackendCountUpdate(serviceName, netName, checkName, igName),
+			},
+			{
+				ResourceName:      "google_compute_region_backend_service.foobar",
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+      {
+				Config: testAccComputeRegionBackendService_withDynamicBackendCount(serviceName, netName, checkName, igName),
+			},
+			{
+				ResourceName:      "google_compute_region_backend_service.foobar",
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+		},
+	})
+}
+
+func testAccComputeRegionBackendService_withDynamicBackendCount(serviceName, netName, hcName, igName string) string {
+	return fmt.Sprintf(`
+locals {
+  zones           = ["europe-west1-b", "europe-west1-c", "europe-west1-d"]
+  s1_count        = 3
+}
+
+resource "google_compute_network" "network" {
+  name    = "%s"
+}
+
+resource "google_compute_region_backend_service" "foobar" {
+  name = "%s"
+  region = "europe-west1"
+
+  dynamic "backend" {
+    for_each = google_compute_instance_group.s1
+    content {
+      balancing_mode = "CONNECTION"
+      group = backend.value.self_link
+    }
+  }
+
+  health_checks = [
+    google_compute_health_check.default.self_link,
+  ]
+}
+
+resource "google_compute_health_check" "default" {
+  name = "%s"
+  tcp_health_check {
+    port = "80"
+  }
+}
+
+resource "google_compute_instance_group" "s1" {
+  count   = local.s1_count
+  name    = "%s-${count.index}"
+  zone    = element(local.zones, count.index)
+  network = google_compute_network.network.self_link
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+`, netName, serviceName, hcName, igName)
+}
+
+func testAccComputeRegionBackendService_withDynamicBackendCountUpdate(serviceName, netName, hcName, igName string) string {
+	return fmt.Sprintf(`
+locals {
+  zones           = ["europe-west1-b", "europe-west1-c", "europe-west1-d"]
+  s1_count        = 1
+}
+
+resource "google_compute_network" "network" {
+  name    = "%s"
+}
+
+resource "google_compute_region_backend_service" "foobar" {
+  name = "%s"
+  region = "europe-west1"
+
+  dynamic "backend" {
+    for_each = google_compute_instance_group.s1
+    content {
+      balancing_mode = "CONNECTION"
+      group = backend.value.self_link
+    }
+  }
+
+  health_checks = [
+    google_compute_health_check.default.self_link,
+  ]
+}
+
+resource "google_compute_health_check" "default" {
+  name = "%s"
+  tcp_health_check {
+    port = "80"
+  }
+}
+
+resource "google_compute_instance_group" "s1" {
+  count   = local.s1_count
+  name    = "%s-${count.index}"
+  zone    = element(local.zones, count.index)
+  network = google_compute_network.network.self_link
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+`, netName, serviceName, hcName, igName)
+}
+
 func testAccComputeRegionBackendService_ilbBasic_withUnspecifiedProtocol(serviceName, checkName string) string {
 	return fmt.Sprintf(`
 resource "google_compute_region_backend_service" "foobar" {