Allow empty ip_addresses list for azurerm_application_gateway (#8209)

azurerm/internal/services/network/application_gateway_resource.go

@@ -123,7 +123,7 @@ func resourceArmApplicationGateway() *schema.Resource {
 						"ip_addresses": {
 							Type:     schema.TypeList,
 							Optional: true,
-							MinItems: 1,
+							MinItems: 0,
 							Elem: &schema.Schema{
 								Type:         schema.TypeString,
 								ValidateFunc: validate.IPv4Address,

azurerm/internal/services/network/tests/application_gateway_resource_test.go

@@ -1034,6 +1034,25 @@ func TestAccAzureRMApplicationGateway_IncludePathWithTargetURL(t *testing.T) {
 	})
 }
 
+func TestAccAzureRMApplicationGateway_backendAddressPoolEmptyIpList(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_application_gateway", "test")
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { acceptance.PreCheck(t) },
+		Providers:    acceptance.SupportedProviders,
+		CheckDestroy: testCheckAzureRMApplicationGatewayDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAzureRMApplicationGateway_backendAddressPoolEmptyIpList(data),
+				Check: resource.ComposeTestCheckFunc(
+					testCheckAzureRMApplicationGatewayExists(data.ResourceName),
+				),
+			},
+			data.ImportStep(),
+		},
+	})
+}
+
 func testCheckAzureRMApplicationGatewayExists(resourceName string) resource.TestCheckFunc {
 	return func(s *terraform.State) error {
 		client := acceptance.AzureProvider.Meta().(*clients.Client).Network.ApplicationGatewaysClient
@@ -5478,3 +5497,75 @@ resource "azurerm_application_gateway" "test" {
 }
 `, template, data.RandomInteger)
 }
+
+func testAccAzureRMApplicationGateway_backendAddressPoolEmptyIpList(data acceptance.TestData) string {
+	template := testAccAzureRMApplicationGateway_template(data)
+	return fmt.Sprintf(`
+%s
+
+# since these variables are re-used - a locals block makes this more maintainable
+locals {
+  backend_address_pool_name      = "${azurerm_virtual_network.test.name}-beap"
+  frontend_port_name             = "${azurerm_virtual_network.test.name}-feport"
+  frontend_ip_configuration_name = "${azurerm_virtual_network.test.name}-feip"
+  http_setting_name              = "${azurerm_virtual_network.test.name}-be-htst"
+  listener_name                  = "${azurerm_virtual_network.test.name}-httplstn"
+  request_routing_rule_name      = "${azurerm_virtual_network.test.name}-rqrt"
+}
+
+resource "azurerm_application_gateway" "test" {
+  name                = "acctestag-%d"
+  resource_group_name = azurerm_resource_group.test.name
+  location            = azurerm_resource_group.test.location
+
+  sku {
+    name     = "Standard_Small"
+    tier     = "Standard"
+    capacity = 2
+  }
+
+  gateway_ip_configuration {
+    name      = "my-gateway-ip-configuration"
+    subnet_id = azurerm_subnet.test.id
+  }
+
+  frontend_port {
+    name = local.frontend_port_name
+    port = 80
+  }
+
+  frontend_ip_configuration {
+    name                 = local.frontend_ip_configuration_name
+    public_ip_address_id = azurerm_public_ip.test.id
+  }
+
+  backend_address_pool {
+    name         = local.backend_address_pool_name
+    ip_addresses = []
+  }
+
+  backend_http_settings {
+    name                  = local.http_setting_name
+    cookie_based_affinity = "Disabled"
+    port                  = 80
+    protocol              = "Http"
+    request_timeout       = 1
+  }
+
+  http_listener {
+    name                           = local.listener_name
+    frontend_ip_configuration_name = local.frontend_ip_configuration_name
+    frontend_port_name             = local.frontend_port_name
+    protocol                       = "Http"
+  }
+
+  request_routing_rule {
+    name                       = local.request_routing_rule_name
+    rule_type                  = "Basic"
+    http_listener_name         = local.listener_name
+    backend_address_pool_name  = local.backend_address_pool_name
+    backend_http_settings_name = local.http_setting_name
+  }
+}
+`, template, data.RandomInteger)
+}