r/azurerm_app_service: Make key_vault_reference_identity_id configurable (#13720)

Solves #13388 by making the user assigned identity id
for looking up key vault secrets configurable.

The attribute is computed to read the default value (at the moment: SystemAssigned ) if no value is specified .
The default value is returned by the API even if no SystemAssigned identity is set for an AppService. Therefore this behaviour should be fine.

Test case succeeded:

Author: patst

internal/services/web/app_service_resource.go

@@ -10,6 +10,7 @@ import (
 	"github.com/hashicorp/terraform-provider-azurerm/helpers/azure"
 	"github.com/hashicorp/terraform-provider-azurerm/helpers/tf"
 	"github.com/hashicorp/terraform-provider-azurerm/internal/clients"
+	msivalidate "github.com/hashicorp/terraform-provider-azurerm/internal/services/msi/validate"
 	"github.com/hashicorp/terraform-provider-azurerm/internal/services/web/parse"
 	"github.com/hashicorp/terraform-provider-azurerm/internal/services/web/validate"
 	"github.com/hashicorp/terraform-provider-azurerm/internal/tags"
@@ -134,6 +135,13 @@ func resourceAppService() *pluginsdk.Resource {
 				Default:  false,
 			},
 
+			"key_vault_reference_identity_id": {
+				Type:         pluginsdk.TypeString,
+				Optional:     true,
+				Computed:     true,
+				ValidateFunc: msivalidate.UserAssignedIdentityID,
+			},
+
 			"logs": schemaAppServiceLogsConfig(),
 
 			"site_config": schemaAppServiceSiteConfig(),
@@ -274,6 +282,10 @@ func resourceAppServiceCreate(d *pluginsdk.ResourceData, meta interface{}) error
 		},
 	}
 
+	if v, ok := d.GetOk("key_vault_reference_identity_id"); ok {
+		siteEnvelope.SiteProperties.KeyVaultReferenceIdentity = utils.String(v.(string))
+	}
+
 	if _, ok := d.GetOk("identity"); ok {
 		appServiceIdentityRaw := d.Get("identity").([]interface{})
 		appServiceIdentity := expandAppServiceIdentity(appServiceIdentityRaw)
@@ -398,6 +410,10 @@ func resourceAppServiceUpdate(d *pluginsdk.ResourceData, meta interface{}) error
 		},
 	}
 
+	if v, ok := d.GetOk("key_vault_reference_identity_id"); ok {
+		siteEnvelope.SiteProperties.KeyVaultReferenceIdentity = utils.String(v.(string))
+	}
+
 	siteEnvelope.SiteProperties.ClientCertEnabled = utils.Bool(d.Get("client_cert_enabled").(bool))
 
 	future, err := client.CreateOrUpdate(ctx, id.ResourceGroup, id.SiteName, siteEnvelope)
@@ -684,6 +700,10 @@ func resourceAppServiceRead(d *pluginsdk.ResourceData, meta interface{}) error {
 			d.Set("possible_outbound_ip_address_list", strings.Split(*props.PossibleOutboundIPAddresses, ","))
 		}
 		d.Set("custom_domain_verification_id", props.CustomDomainVerificationID)
+
+		if props.KeyVaultReferenceIdentity != nil {
+			d.Set("key_vault_reference_identity_id", props.KeyVaultReferenceIdentity)
+		}
 	}
 
 	appSettings := flattenAppServiceAppSettings(appSettingsResp.Properties)

internal/services/web/app_service_resource_test.go

@@ -1928,6 +1928,21 @@ func TestAccAppServiceEnvironment_scopeNameCheck(t *testing.T) {
 	})
 }
 
+func TestAccAppService_keyVaultUserAssignedIdentity(t *testing.T) {
+	data := acceptance.BuildTestData(t, "azurerm_app_service", "test")
+	r := AppServiceResource{}
+
+	data.ResourceTest(t, r, []acceptance.TestStep{
+		{
+			Config: r.KeyVaultUserAssignedIdentity(data),
+			Check: acceptance.ComposeTestCheckFunc(
+				check.That(data.ResourceName).ExistsInAzure(r),
+			),
+		},
+		data.ImportStep(),
+	})
+}
+
 func (r AppServiceResource) Exists(ctx context.Context, clients *clients.Client, state *pluginsdk.InstanceState) (*bool, error) {
 	id, err := parse.AppServiceID(state.ID)
 	if err != nil {
@@ -5591,3 +5606,47 @@ resource "azurerm_app_service" "test" {
 }
 `, data.RandomInteger, data.Locations.Primary, data.RandomInteger, data.RandomInteger, data.RandomInteger)
 }
+
+func (r AppServiceResource) KeyVaultUserAssignedIdentity(data acceptance.TestData) string {
+	return fmt.Sprintf(`
+provider "azurerm" {
+  features {}
+}
+
+resource "azurerm_resource_group" "test" {
+  name     = "acctestRG-%d"
+  location = "%s"
+}
+
+resource "azurerm_user_assigned_identity" "test" {
+  name                = "acct-%d"
+  resource_group_name = azurerm_resource_group.test.name
+  location            = azurerm_resource_group.test.location
+}
+
+resource "azurerm_app_service_plan" "test" {
+  name                = "acctestASP-%d"
+  location            = azurerm_resource_group.test.location
+  resource_group_name = azurerm_resource_group.test.name
+
+  sku {
+    tier = "Standard"
+    size = "S1"
+  }
+}
+
+resource "azurerm_app_service" "test" {
+  name                = "acctestAS-%d"
+  location            = azurerm_resource_group.test.location
+  resource_group_name = azurerm_resource_group.test.name
+  app_service_plan_id = azurerm_app_service_plan.test.id
+
+  key_vault_reference_identity_id = azurerm_user_assigned_identity.test.id
+
+  identity {
+    type         = "UserAssigned"
+    identity_ids = [azurerm_user_assigned_identity.test.id]
+  }
+}
+`, data.RandomInteger, data.Locations.Primary, data.RandomInteger, data.RandomInteger, data.RandomInteger)
+}

website/docs/r/app_service.html.markdown

@@ -87,6 +87,8 @@ The following arguments are supported:
 
 * `https_only` - (Optional) Can the App Service only be accessed via HTTPS? Defaults to `false`.
 
+* `key_vault_reference_identity_id` - (Optional) The User Assigned Identity Id used for looking up KeyVault secrets. The identity must be assigned to the application. [For more information see - Access vaults with a user-assigned identity](https://docs.microsoft.com/en-us/azure/app-service/app-service-key-vault-references#access-vaults-with-a-user-assigned-identity)
+
 * `logs` - (Optional) A `logs` block as defined below.
 
 * `storage_account` - (Optional) One or more `storage_account` blocks as defined below.