fix sending disableConnectionDrainOnFailover (#7326) (#13897)

* fix sending disableConnectionDrainOnFailover

* add a test

* update tests

---------

Signed-off-by: Modular Magician <magic-modules@google.com>
Co-authored-by: Edward Sun <sunedward@google.com>

Author: modular-magician

.changelog/7326.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+compute: fixed the error of invalid value for field `resource.failoverPolicy` when UDP is selected on `google_compute_region_backend_service`
+```

google/resource_compute_region_backend_service.go

@@ -490,6 +490,7 @@ Defaults to 1024.`,
 					Schema: map[string]*schema.Schema{
 						"disable_connection_drain_on_failover": {
 							Type:     schema.TypeBool,
+							Computed: true,
 							Optional: true,
 							Description: `On failover or failback, this field indicates whether connection drain
 will be honored. Setting this to true has the following effect: connections
@@ -503,6 +504,7 @@ The default is false.`,
 						},
 						"drop_traffic_if_unhealthy": {
 							Type:     schema.TypeBool,
+							Computed: true,
 							Optional: true,
 							Description: `This option is used only when no healthy VMs are detected in the primary
 and backup instance groups. When set to true, traffic is dropped. When
@@ -3238,7 +3240,7 @@ func expandComputeRegionBackendServiceFailoverPolicy(v interface{}, d TerraformR
 	transformedDisableConnectionDrainOnFailover, err := expandComputeRegionBackendServiceFailoverPolicyDisableConnectionDrainOnFailover(original["disable_connection_drain_on_failover"], d, config)
 	if err != nil {
 		return nil, err
-	} else {
+	} else if val := reflect.ValueOf(transformedDisableConnectionDrainOnFailover); val.IsValid() && !isEmptyValue(val) {
 		transformed["disableConnectionDrainOnFailover"] = transformedDisableConnectionDrainOnFailover
 	}
 

google/resource_compute_region_backend_service_test.go

@@ -222,6 +222,45 @@ func TestAccComputeRegionBackendService_withBackendAndIAP(t *testing.T) {
 	})
 }
 
+func TestAccComputeRegionBackendService_UDPFailOverPolicyUpdate(t *testing.T) {
+	t.Parallel()
+
+	serviceName := fmt.Sprintf("tf-test-%s", randString(t, 10))
+	checkName := fmt.Sprintf("tf-test-%s", randString(t, 10))
+
+	vcrTest(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckComputeRegionBackendServiceDestroyProducer(t),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccComputeRegionBackendService_UDPFailOverPolicyHasDrain(serviceName, "TCP", "true", checkName),
+			},
+			{
+				ResourceName:      "google_compute_region_backend_service.foobar",
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+			{
+				Config: testAccComputeRegionBackendService_UDPFailOverPolicyHasDrain(serviceName, "TCP", "false", checkName),
+			},
+			{
+				ResourceName:      "google_compute_region_backend_service.foobar",
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+			{
+				Config: testAccComputeRegionBackendService_UDPFailOverPolicy(serviceName, "UDP", "false", checkName),
+			},
+			{
+				ResourceName:      "google_compute_region_backend_service.foobar",
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+		},
+	})
+}
+
 func testAccComputeRegionBackendService_ilbBasic(serviceName, checkName string) string {
 	return fmt.Sprintf(`
 resource "google_compute_region_backend_service" "foobar" {
@@ -283,6 +322,59 @@ resource "google_compute_health_check" "health_check" {
 `, serviceName, checkName)
 }
 
+func testAccComputeRegionBackendService_UDPFailOverPolicy(serviceName, protocol, failover, checkName string) string {
+	return fmt.Sprintf(`
+resource "google_compute_region_backend_service" "foobar" {
+  name          = "%s"
+  health_checks = [google_compute_health_check.zero.self_link]
+  region        = "us-central1"
+
+  protocol = "%s"
+  failover_policy {
+      # Disable connection drain on failover cannot be set when the protocol is UDP
+      drop_traffic_if_unhealthy = "%s"
+  }
+}
+
+resource "google_compute_health_check" "zero" {
+  name               = "%s"
+  check_interval_sec = 1
+  timeout_sec        = 1
+
+  tcp_health_check {
+    port = "80"
+  }
+}
+`, serviceName, protocol, failover, checkName)
+}
+
+func testAccComputeRegionBackendService_UDPFailOverPolicyHasDrain(serviceName, protocol, failover, checkName string) string {
+	return fmt.Sprintf(`
+resource "google_compute_region_backend_service" "foobar" {
+  name          = "%s"
+  health_checks = [google_compute_health_check.zero.self_link]
+  region        = "us-central1"
+
+  protocol = "%s"
+  failover_policy {
+      # Disable connection drain on failover cannot be set when the protocol is UDP
+      drop_traffic_if_unhealthy = "%s"
+      disable_connection_drain_on_failover = "%s"
+  }
+}
+
+resource "google_compute_health_check" "zero" {
+  name               = "%s"
+  check_interval_sec = 1
+  timeout_sec        = 1
+
+  tcp_health_check {
+    port = "80"
+  }
+}
+`, serviceName, protocol, failover, failover, checkName)
+}
+
 func testAccComputeRegionBackendService_basic(serviceName, checkName string) string {
 	return fmt.Sprintf(`
 resource "google_compute_region_backend_service" "foobar" {