non-NIC0 ILB support (#2732)

Merged PR #2732.

products/compute/api.yaml

@@ -2273,6 +2273,14 @@ objects:
               the field must be in [0, 1]. This configures the sampling rate of requests to the load balancer
               where 1.0 means all logged requests are reported and 0.0 means no logged requests are reported.
               The default value is 1.0.
+      - !ruby/object:Api::Type::ResourceRef
+        resource: 'Network'
+        name: 'network'
+        imports: 'selfLink'
+        description: |
+          The URL of the network to which this backend service belongs.
+          This field can only be specified when the load balancing scheme is set to INTERNAL.
+        min_version: beta
   - !ruby/object:Api::Resource
     name: 'BackendServiceSignedUrlKey'
     kind: 'compute#BackendServiceSignedUrlKey'

third_party/terraform/tests/resource_compute_region_backend_service_test.go.erb

@@ -103,6 +103,35 @@ func TestAccComputeRegionBackendService_withBackendAndUpdate(t *testing.T) {
 	})
 }
 
+<% unless version == 'ga' -%>
+func TestAccComputeRegionBackendService_withBackendMultiNic(t *testing.T) {
+        t.Parallel()
+
+        serviceName := fmt.Sprintf("tf-test-%s", acctest.RandString(10))
+        net1Name := fmt.Sprintf("tf-test-%s", acctest.RandString(10))
+        net2Name := fmt.Sprintf("tf-test-%s", acctest.RandString(10))
+        igName := fmt.Sprintf("tf-test-%s", acctest.RandString(10))
+        itName := fmt.Sprintf("tf-test-%s", acctest.RandString(10))
+        checkName := fmt.Sprintf("tf-test-%s", acctest.RandString(10))
+        resource.Test(t, resource.TestCase{
+                PreCheck:     func() { testAccPreCheck(t) },
+                Providers:    testAccProviders,
+                CheckDestroy: testAccCheckComputeRegionBackendServiceDestroy,
+                Steps: []resource.TestStep{
+                        resource.TestStep{
+                                Config: testAccComputeRegionBackendService_withBackendMultiNic(
+                                        serviceName, net1Name, net2Name, igName, itName, checkName, 10),
+                        },
+                        {
+                                ResourceName:      "google_compute_region_backend_service.lipsum",
+                                ImportState:       true,
+                                ImportStateVerify: true,
+                        },
+                },
+        })
+}
+<% end -%>
+
 func TestAccComputeRegionBackendService_withConnectionDrainingAndUpdate(t *testing.T) {
 	t.Parallel()
 
@@ -519,6 +548,107 @@ resource "google_compute_health_check" "default" {
 `, serviceName, timeout, igName, itName, checkName)
 }
 
+<% unless version == 'ga' -%>
+func testAccComputeRegionBackendService_withBackendMultiNic(
+        serviceName, net1Name, net2Name, igName, itName, checkName string, timeout int64) string {
+        return fmt.Sprintf(`
+data "google_compute_image" "my_image" {
+  family  = "debian-9"
+  project = "debian-cloud"
+}
+
+resource "google_compute_region_backend_service" "lipsum" {
+  name        = "%s"
+  description = "Hello World 1234"
+  protocol    = "TCP"
+  region      = "us-central1"
+  timeout_sec = %v
+
+  backend {
+    group = google_compute_instance_group_manager.foobar.instance_group
+    failover = true
+  }
+
+  failover_policy {
+    disable_connection_drain_on_failover = true
+    drop_traffic_if_unhealthy = true
+    failover_ratio = 0.4
+  }
+
+  network = google_compute_network.network2.self_link
+
+  health_checks = [google_compute_health_check.default.self_link]
+}
+
+resource "google_compute_network" "network1" {
+  name                            = "%s"
+  auto_create_subnetworks         = false
+}
+
+resource "google_compute_subnetwork" "subnet1" {
+  name                     = "%s"
+  ip_cidr_range            = "10.0.1.0/24"
+  region                   = "us-central1"
+  private_ip_google_access = true
+  network                  = google_compute_network.network1.self_link
+}
+
+resource "google_compute_network" "network2" {
+  name                            = "%s"
+  auto_create_subnetworks         = false
+}
+
+resource "google_compute_subnetwork" "subnet2" {
+  name                     = "%s"
+  ip_cidr_range            = "10.0.2.0/24"
+  region                   = "us-central1"
+  private_ip_google_access = true
+  network                  = google_compute_network.network2.self_link
+}
+
+resource "google_compute_instance_group_manager" "foobar" {
+  name               = "%s"
+  version {
+    instance_template  = google_compute_instance_template.foobar.self_link
+    name               = "primary"
+  }
+  base_instance_name = "foobar"
+  zone               = "us-central1-f"
+  target_size        = 1
+}
+
+resource "google_compute_instance_template" "foobar" {
+  name         = "%s"
+  machine_type = "n1-standard-1"
+
+  network_interface {
+    subnetwork = google_compute_subnetwork.subnet1.self_link
+  }
+
+  network_interface {
+    subnetwork = google_compute_subnetwork.subnet2.self_link
+  }
+
+  disk {
+    source_image = data.google_compute_image.my_image.self_link
+    auto_delete  = true
+    boot         = true
+  }
+}
+
+resource "google_compute_health_check" "default" {
+  name               = "%s"
+  check_interval_sec = 1
+  timeout_sec        = 1
+
+  tcp_health_check {
+    port = 443
+  }
+}
+`, serviceName, timeout, net1Name, net1Name, net2Name, net2Name, igName, itName, checkName)
+}
+<% end -%>
+
 func testAccComputeRegionBackendService_withConnectionDraining(serviceName, checkName string, drainingTimeout int64) string {
 	return fmt.Sprintf(`
 resource "google_compute_region_backend_service" "foobar" {