Update ASB Sample

 Added EF Inceptor used for adding a Token

samples/ASBTaskQueue/Greetings/Adaptors/Data/AzureAdAuthenticationDbConnectionInterceptor.cs

@@ -0,0 +1,106 @@
+using System;
+using System.Data.Common;
+using System.Threading;
+using System.Threading.Tasks;
+using Azure.Core;
+using Azure.Identity;
+using Microsoft.Data.SqlClient;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+
+namespace Greetings.Adaptors.Data
+{
+    public class AzureAdAuthenticationDbConnectionInterceptor : DbConnectionInterceptor
+    {
+        // See https://docs.microsoft.com/azure/active-directory/managed-identities-azure-resources/services-support-managed-identities#azure-sql
+        private static readonly string[] _azureSqlScopes = new[] { "https://database.windows.net//.default" };
+        private const int _cacheLifeTime = 5;
+
+        private static readonly TokenCredential _credential = new ChainedTokenCredential(
+            new ManagedIdentityCredential(),
+            new VisualStudioCredential());
+
+        private static AccessToken _token;
+        private static SemaphoreSlim _semaphoreToken = new SemaphoreSlim(1, 1);
+
+        public override InterceptionResult ConnectionOpening(
+            DbConnection connection,
+            ConnectionEventData eventData,
+            InterceptionResult result)
+        {
+            var sqlConnection = (SqlConnection)connection;
+            if (DoesConnectionNeedAccessToken(sqlConnection))
+                sqlConnection.AccessToken = GetAccessToken();
+
+            return base.ConnectionOpening(connection, eventData, result);
+        }
+
+        public override async ValueTask<InterceptionResult> ConnectionOpeningAsync(
+            DbConnection connection,
+            ConnectionEventData eventData,
+            InterceptionResult result,
+            CancellationToken cancellationToken = default)
+        {
+            var sqlConnection = (SqlConnection)connection;
+            if (DoesConnectionNeedAccessToken(sqlConnection))
+                sqlConnection.AccessToken = await GetAccessTokenAsync();
+
+            return await base.ConnectionOpeningAsync(connection, eventData, result, cancellationToken);
+        }
+
+        private static bool DoesConnectionNeedAccessToken(SqlConnection connection)
+        {
+            //
+            // Only try to get a token from AAD if
+            //  - We connect to an Azure SQL instance; and
+            //  - The connection doesn't specify a username.
+            //
+            var connectionStringBuilder = new SqlConnectionStringBuilder(connection.ConnectionString);
+
+            return connectionStringBuilder.DataSource.Contains("database.windows.net", StringComparison.OrdinalIgnoreCase) && string.IsNullOrEmpty(connectionStringBuilder.UserID);
+        }
+
+        private string GetAccessToken()
+        {
+            _semaphoreToken.Wait();
+            try
+            {
+                //If the Token has more than 5 minutes Validity
+                if (DateTime.UtcNow.AddMinutes(_cacheLifeTime) <= _token.ExpiresOn.UtcDateTime)
+                    return _token.Token;
+
+                var tokenRequestContext = new TokenRequestContext(_azureSqlScopes);
+                var token = _credential.GetToken(tokenRequestContext, CancellationToken.None);
+
+                _token = token;
+
+                return token.Token;
+            }
+            finally
+            {
+                _semaphoreToken.Release();
+            }
+        }
+
+        private async Task<string> GetAccessTokenAsync()
+        {
+            await _semaphoreToken.WaitAsync();
+            try
+            {
+                //If the Token has more than 5 minutes Validity
+                if (DateTime.UtcNow.AddMinutes(_cacheLifeTime) <= _token.ExpiresOn.UtcDateTime)
+                    return _token.Token;
+
+                var tokenRequestContext = new TokenRequestContext(_azureSqlScopes);
+                var token = await _credential.GetTokenAsync(tokenRequestContext, CancellationToken.None);
+
+                _token = token;
+
+                return token.Token;
+            }
+            finally
+            {
+                _semaphoreToken.Release();
+            }
+        }
+    }
+}

samples/ASBTaskQueue/Greetings/Greetings.csproj

@@ -13,6 +13,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Azure.Identity" Version="1.5.0" />
     <PackageReference Include="Microsoft.EntityFrameworkCore" Version="5.0.11" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" Version="5.0.11" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="5.0.11" />

samples/ASBTaskQueue/GreetingsSender.Web/Controllers/HomeController.cs

@@ -54,6 +54,8 @@ public async Task<IActionResult> DepositMessage()
             var greetingAsync = new GreetingAsyncEvent("Deposit Hello from the web");
             var greeting = new GreetingEvent("Deposit Hello from the web");
 
+            await _commandProcessor.DepositPostAsync(greetingAsync);
+
             _context.Greetings.Add(greeting);
             _context.GreetingsAsync.Add(greetingAsync);
             await _context.SaveChangesAsync();

samples/ASBTaskQueue/GreetingsSender.Web/Program.cs

@@ -24,6 +24,7 @@
 builder.Services.AddDbContext<GreetingsDataContext>(o =>
 {
     o.UseSqlServer(dbConnString);
+    //o.AddInterceptors(new AzureAdAuthenticationDbConnectionInterceptor());
 });
 
 //Services
@@ -67,7 +68,7 @@
     var services = serviceScope.ServiceProvider;
     var dbContext = services.GetService<GreetingsDataContext>();
 
-    dbContext.Database.EnsureCreated();
+    //dbContext.Database.EnsureCreated();
 }
 else
 {