azurerm_application_gateway: Support for Hostname

azurerm/resource_arm_application_gateway.go

@@ -146,6 +146,11 @@ func resourceArmApplicationGateway() *schema.Resource {
 							}, true),
 						},
 
+						"host_name": {
+							Type:     schema.TypeString,
+							Optional: true,
+						},
+
 						"pick_host_name_from_backend_address": {
 							Type:     schema.TypeBool,
 							Optional: true,
@@ -915,6 +920,16 @@ func resourceArmApplicationGatewayCreateUpdate(d *schema.ResourceData, meta inte
 		},
 	}
 
+	for _, backendHttpSettings := range *backendHTTPSettingsCollection {
+		backendHttpSettingsProperties := *backendHttpSettings.ApplicationGatewayBackendHTTPSettingsPropertiesFormat
+		hostName := *backendHttpSettingsProperties.HostName
+		pick := *backendHttpSettingsProperties.PickHostNameFromBackendAddress
+
+		if hostName != "" && pick {
+			return fmt.Errorf("Only one of `host_name` or `pick_host_name_from_backend_address` can be set")
+		}
+	}
+
 	for _, probe := range *probes {
 		probeProperties := *probe.ApplicationGatewayProbePropertiesFormat
 		host := *probeProperties.Host
@@ -1255,6 +1270,7 @@ func expandApplicationGatewayBackendHTTPSettings(d *schema.ResourceData, gateway
 		port := int32(v["port"].(int))
 		protocol := v["protocol"].(string)
 		cookieBasedAffinity := v["cookie_based_affinity"].(string)
+		hostName := v["host_name"].(string)
 		pickHostNameFromBackendAddress := v["pick_host_name_from_backend_address"].(bool)
 		requestTimeout := int32(v["request_timeout"].(int))
 
@@ -1263,6 +1279,7 @@ func expandApplicationGatewayBackendHTTPSettings(d *schema.ResourceData, gateway
 			ApplicationGatewayBackendHTTPSettingsPropertiesFormat: &network.ApplicationGatewayBackendHTTPSettingsPropertiesFormat{
 				CookieBasedAffinity:            network.ApplicationGatewayCookieBasedAffinity(cookieBasedAffinity),
 				Path:                           utils.String(path),
+				HostName:                       utils.String(hostName),
 				PickHostNameFromBackendAddress: utils.Bool(pickHostNameFromBackendAddress),
 				Port:                           utils.Int32(port),
 				Protocol:                       network.ApplicationGatewayProtocol(protocol),
@@ -1332,6 +1349,10 @@ func flattenApplicationGatewayBackendHTTPSettings(input *[]network.ApplicationGa
 				output["port"] = int(*port)
 			}
 
+			if hostName := props.HostName; hostName != nil {
+				output["host_name"] = *hostName
+			}
+
 			if pickHostNameFromBackendAddress := props.PickHostNameFromBackendAddress; pickHostNameFromBackendAddress != nil {
 				output["pick_host_name_from_backend_address"] = *pickHostNameFromBackendAddress
 			}

azurerm/resource_arm_application_gateway_test.go

@@ -260,6 +260,32 @@ func TestAccAzureRMApplicationGateway_probesPickHostNameFromBackendHTTPSettings(
 	})
 }
 
+func TestAccAzureRMApplicationGateway_backendHttpSettingsHostName(t *testing.T) {
+	resourceName := "azurerm_application_gateway.test"
+	ri := tf.AccRandTimeInt()
+	hostName := "example.com"
+
+	resource.ParallelTest(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testCheckAzureRMApplicationGatewayDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAzureRMApplicationGateway_backendHttpSettingsHostName(ri, testLocation(), hostName),
+				Check: resource.ComposeTestCheckFunc(
+					testCheckAzureRMApplicationGatewayExists(resourceName),
+					resource.TestCheckResourceAttr(resourceName, "backend_http_settings.0.host_name", hostName),
+				),
+			},
+			{
+				ResourceName:      resourceName,
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+		},
+	})
+}
+
 func TestAccAzureRMApplicationGateway_settingsPickHostNameFromBackendAddress(t *testing.T) {
 	resourceName := "azurerm_application_gateway.test"
 	ri := tf.AccRandTimeInt()
@@ -1169,6 +1195,78 @@ resource "azurerm_application_gateway" "test" {
 `, template, rInt)
 }
 
+func testAccAzureRMApplicationGateway_backendHttpSettingsHostName(rInt int, location string, hostName string) string {
+	template := testAccAzureRMApplicationGateway_template(rInt, location)
+	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 = "${local.backend_address_pool_name}"
+  }
+
+  backend_http_settings {
+    name                  = "${local.http_setting_name}"
+    cookie_based_affinity = "Disabled"
+    host_name             = "%s"
+    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, rInt, hostName)
+}
+
 func testAccAzureRMApplicationGateway_settingsPickHostNameFromBackendAddress(rInt int, location string) string {
 	template := testAccAzureRMApplicationGateway_template(rInt, location)
 	return fmt.Sprintf(`

website/docs/r/application_gateway.html.markdown

@@ -204,6 +204,8 @@ A `backend_http_settings` block supports the following:
 
 * `request_timeout` - (Required) The request timeout in seconds, which must be between 1 and 86400 seconds.
 
+* `host_name` - (Optional) Host header to be sent to the backend servers. Cannot be set if `pick_host_name_from_backend_address` is set to `true`.
+
 * `pick_host_name_from_backend_address` - (Optional) Whether host header should be picked from the host name of the backend server. Defaults to `false`.
 
 * `authentication_certificate` - (Optional) One or more `authentication_certificate` blocks.