Tutorial: Secure Azure SQL Database connection from App Service using a managed identity

App Service provides a highly scalable, self-patching web hosting service in Azure. It also provides a managed identity for your app, which is a turn-key solution for securing access to Azure SQL Database and other Azure services. Managed identities in App Service make your app more secure by eliminating secrets from your app, such as credentials in the connection strings. In this tutorial, you will add managed identity to the sample web app you built in one of the following tutorials:

When you're finished, your sample app will connect to SQL Database securely without the need of username and passwords.

Note

The steps covered in this tutorial support the following versions:

  • .NET Framework 4.7.2 and above.
  • .NET Core 2.2 and above.

What you will learn:

  • Enable managed identities
  • Grant SQL Database access to the managed identity
  • Configure Entity Framework to use Azure AD authentication with SQL Database
  • Connect to SQL Database from Visual Studio using Azure AD authentication

Note

Azure AD authentication is different from Integrated Windows authentication in on-premises Active Directory (AD DS). AD DS and Azure AD use completely different authentication protocols. For more information, see Azure AD Domain Services documentation.

If you don't have an Azure subscription, create a free account before you begin.

Prerequisites

This article continues where you left off in Tutorial: Build an ASP.NET app in Azure with SQL Database or Tutorial: Build an ASP.NET Core and SQL Database app in Azure App Service. If you haven't already, follow one of the two tutorials first. Alternatively, you can adapt the steps for your own .NET app with SQL Database.

To debug your app using SQL Database as the back end, make sure that you've allowed client connection from your computer. If not, add the client IP by following the steps at Manage server-level IP firewall rules using the Azure portal.

Use Azure Cloud Shell

Azure hosts Azure Cloud Shell, an interactive shell environment that you can use through your browser. Cloud Shell lets you use either bash or PowerShell to work with Azure services. You can use the Cloud Shell pre-installed commands to run the code in this article without having to install anything on your local environment.

To launch Azure Cloud Shell:

Option Example/Link
Select Try It in the upper-right corner of a code block. Selecting Try It doesn't automatically copy the code to Cloud Shell. Example of Try It for Azure Cloud Shell
Go to https://shell.azure.com or select the Launch Cloud Shell button to open Cloud Shell in your browser. Launch Cloud Shell in a new window
Select the Cloud Shell button on the top-right menu bar in the Azure portal. Cloud Shell button in the Azure portal

To run the code in this article in Azure Cloud Shell:

  1. Launch Cloud Shell.

  2. Select the Copy button on a code block to copy the code.

  3. Paste the code into the Cloud Shell session with Ctrl+Shift+V on Windows and Linux, or Cmd+Shift+V on macOS.

  4. Press Enter to run the code.

Grant database access to Azure AD user

First enable Azure AD authentication to SQL Database by assigning an Azure AD user as the Active Directory admin of the SQL Database server. This user is different from the Microsoft account you used to sign up for your Azure subscription. It must be a user that you created, imported, synced, or invited into Azure AD. For more information on allowed Azure AD users, see Azure AD features and limitations in SQL Database.

If your Azure AD tenant doesn't have a user yet, create one by following the steps at Add or delete users using Azure Active Directory.

Find the object ID of the Azure AD user using the az ad user list and replace <user-principal-name>. The result is saved to a variable.

azureaduser=$(az ad user list --filter "userPrincipalName eq '<user-principal-name>'" --query [].objectId --output tsv)

Tip

To see the list of all user principal names in Azure AD, run az ad user list --query [].userPrincipalName.

Add this Azure AD user as an Active Directory admin using az sql server ad-admin create command in the Cloud Shell. In the following command, replace <server-name> with the SQL Database server name (without the .database.windows.net suffix).

az sql server ad-admin create --resource-group myResourceGroup --server-name <server-name> --display-name ADMIN --object-id $azureaduser

For more information on adding an Active Directory admin, see Provision an Azure Active Directory administrator for your Azure SQL Database Server

Set up Visual Studio

Windows

Visual Studio for Windows is integrated with Azure AD authentication. To enable development and debugging in Visual Studio, add your Azure AD user in Visual Studio by selecting File > Account Settings from the menu, and click Add an account.

To set the Azure AD user for Azure service authentication, select Tools > Options from the menu, then select Azure Service Authentication > Account Selection. Select the Azure AD user you added and click OK.

You're now ready to develop and debug your app with the SQL Database as the back end, using Azure AD authentication.

MacOS

Visual Studio for Mac is not integrated with Azure AD authentication. However, the Microsoft.Azure.Services.AppAuthentication library that you will use later can use tokens from Azure CLI. To enable development and debugging in Visual Studio, first you need to install Azure CLI on your local machine.

Once Azure CLI is installed on your local machine, sign in to Azure CLI with the following command using your Azure AD user:

az login --allow-no-subscriptions

You're now ready to develop and debug your app with the SQL Database as the back end, using Azure AD authentication.

Modify your project

The steps you follow for your project depends on whether it's an ASP.NET project or an ASP.NET Core project.

Modify ASP.NET

In Visual Studio, open the Package Manager Console and add the NuGet package Microsoft.Azure.Services.AppAuthentication:

Install-Package Microsoft.Azure.Services.AppAuthentication -Version 1.3.0

In Web.config, working from the top of the file and make the following changes:

  • In <configSections>, add the following section declaration in it:

    <section name="SqlAuthenticationProviders" type="System.Data.SqlClient.SqlAuthenticationProviderConfigurationSection, System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
    
  • below the closing </configSections> tag, add the following XML code for <SqlAuthenticationProviders>.

    <SqlAuthenticationProviders>
      <providers>
        <add name="Active Directory Interactive" type="Microsoft.Azure.Services.AppAuthentication.SqlAppAuthenticationProvider, Microsoft.Azure.Services.AppAuthentication" />
      </providers>
    </SqlAuthenticationProviders>
    
  • Find the connection string called MyDbConnection and replace its connectionString value with "server=tcp:<server-name>.database.windows.net;database=<db-name>;UID=AnyString;Authentication=Active Directory Interactive". Replace <server-name> and <db-name> with your server name and database name.

That's every thing you need to connect to SQL Database. When debugging in Visual Studio, your code uses the Azure AD user you configured in Set up Visual Studio. You'll set up the SQL Database server later to allow connection from the managed identity of your App Service app.

Type Ctrl+F5 to run the app again. The same CRUD app in your browser is now connecting to the Azure SQL Database directly, using Azure AD authentication. This setup lets you run database migrations from Visual Studio.

Modify ASP.NET Core

In Visual Studio, open the Package Manager Console and add the NuGet package Microsoft.Azure.Services.AppAuthentication:

Install-Package Microsoft.Azure.Services.AppAuthentication -Version 1.3.0

In the ASP.NET Core and SQL Database tutorial, the MyDbConnection connection string isn't used at all because the local development environment uses a Sqlite database file, and the Azure production environment uses a connection string from App Service. With Active Directory authentication, you want both environments to use the same connection string. In appsettings.json, replace the value of the MyDbConnection connection string with:

"Server=tcp:<server-name>.database.windows.net,1433;Database=<database-name>;"

In Startup.cs, remove the code section that you added before:

// Use SQL Database if in Azure, otherwise, use SQLite
if (Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") == "Production")
    services.AddDbContext<MyDatabaseContext>(options =>
            options.UseSqlServer(Configuration.GetConnectionString("MyDbConnection")));
else
    services.AddDbContext<MyDatabaseContext>(options =>
            options.UseSqlite("Data Source=localdatabase.db"));

// Automatically perform database migration
services.BuildServiceProvider().GetService<MyDatabaseContext>().Database.Migrate();

And replace it with the following code:

services.AddDbContext<MyDatabaseContext>(options => {
    options.UseSqlServer(Configuration.GetConnectionString("MyDbConnection"));
});

Next, you supply the Entity Framework database context with the access token for the SQL Database. In Data\MyDatabaseContext.cs, add the following code inside the curly braces of the empty MyDatabaseContext (DbContextOptions<MyDatabaseContext> options) constructor:

var conn = (System.Data.SqlClient.SqlConnection)Database.GetDbConnection();
conn.AccessToken = (new Microsoft.Azure.Services.AppAuthentication.AzureServiceTokenProvider()).GetAccessTokenAsync("https://database.windows.net/").Result;

Tip

This demonstration code is synchronous for clarity. For more information, see Asynchronous guide for constructors.

That's every thing you need to connect to SQL Database. When debugging in Visual Studio, your code uses the Azure AD user you configured in Set up Visual Studio. You'll set up the SQL Database server later to allow connection from the managed identity of your App Service app. The AzureServiceTokenProvider class caches the token in memory and retrieves it from Azure AD just before expiration. You don't need any custom code to refresh the token.

Type Ctrl+F5 to run the app again. The same CRUD app in your browser is now connecting to the Azure SQL Database directly, using Azure AD authentication. This setup lets you run database migrations from Visual Studio.

Use managed identity connectivity

Next, you configure your App Service app to connect to SQL Database with a system-assigned managed identity.

Enable managed identity on app

To enable a managed identity for your Azure app, use the az webapp identity assign command in the Cloud Shell. In the following command, replace <app-name>.

az webapp identity assign --resource-group myResourceGroup --name <app-name>

Here's an example of the output:

{
  "additionalProperties": {},
  "principalId": "21dfa71c-9e6f-4d17-9e90-1d28801c9735",
  "tenantId": "72f988bf-86f1-41af-91ab-2d7cd011db47",
  "type": "SystemAssigned"
}

Add managed identity to an Azure AD group

To grant this identity access to your SQL Database, you need to add it to an Azure AD group. In the Cloud Shell, add it to a new group called myAzureSQLDBAccessGroup, shown in the following script:

groupid=$(az ad group create --display-name myAzureSQLDBAccessGroup --mail-nickname myAzureSQLDBAccessGroup --query objectId --output tsv)
msiobjectid=$(az webapp identity show --resource-group myResourceGroup --name <app-name> --query principalId --output tsv)
az ad group member add --group $groupid --member-id $msiobjectid
az ad group member list -g $groupid

If you want to see the full JSON output for each command, drop the parameters --query objectId --output tsv.

Grant permissions to Azure AD group

In the Cloud Shell, sign in to SQL Database by using the SQLCMD command. Replace <server-name> with your SQL Database server name, <db-name> with the database name your app uses, and <aad-user-name> and <aad-password> with your Azure AD user's credentials.

sqlcmd -S <server-name>.database.windows.net -d <db-name> -U <aad-user-name> -P "<aad-password>" -G -l 30

In the SQL prompt for the database you want, run the following commands to add the Azure AD group and grant the permissions your app needs. For example,

CREATE USER [myAzureSQLDBAccessGroup] FROM EXTERNAL PROVIDER;
ALTER ROLE db_datareader ADD MEMBER [myAzureSQLDBAccessGroup];
ALTER ROLE db_datawriter ADD MEMBER [myAzureSQLDBAccessGroup];
ALTER ROLE db_ddladmin ADD MEMBER [myAzureSQLDBAccessGroup];
GO

Type EXIT to return to the Cloud Shell prompt.

Modify connection string

Remember that the same changes you made in Web.config or appsettings.json works with the managed identity, so the only thing to do is to remove the existing connection string in App Service, which Visual Studio created deploying your app the first time. Use the following command, but replace <app-name> with the name of your app.

az webapp config connection-string delete --resource-group myResourceGroup --name <app-name> --setting-names MyDbConnection

Publish your changes

All that's left now is to publish your changes to Azure.

If you came from Tutorial: Build an ASP.NET app in Azure with SQL Database, publish your changes in Visual Studio. In the Solution Explorer, right-click your DotNetAppSqlDb project and select Publish.

Publish from Solution Explorer

In the publish page, click Publish.

If you came from Tutorial: Build an ASP.NET Core and SQL Database app in Azure App Service, publish your changes using Git, with the following commands:

git commit -am "configure managed identity"
git push azure master

When the new webpage shows your to-do list, your app is connecting to the database using the managed identity.

Azure app after Code First Migration

You should now be able to edit the to-do list as before.

Clean up resources

In the preceding steps, you created Azure resources in a resource group. If you don't expect to need these resources in the future, delete the resource group by running the following command in the Cloud Shell:

az group delete --name myResourceGroup

This command may take a minute to run.

Next steps

What you learned:

  • Enable managed identities
  • Grant SQL Database access to the managed identity
  • Configure Entity Framework to use Azure AD authentication with SQL Database
  • Connect to SQL Database from Visual Studio using Azure AD authentication

Advance to the next tutorial to learn how to map a custom DNS name to your web app.