Introduce new authentication provider Unauthenticated as the default

schemas/dab.draft.schema.json

@@ -368,6 +368,10 @@
                     {
                       "const": "Custom",
                       "description": "Custom authentication provider defined by the user. Use the JWT property to configure the custom provider."
+                    },
+                    {
+                      "const": "Unauthenticated",
+                      "description": "Unauthenticated provider where all operations run as anonymous. Use when Data API builder is behind an app gateway or APIM where authentication is handled externally."
                     }
                   ],
                   "default": "AppService"

src/Cli.Tests/InitTests.cs

@@ -301,6 +301,7 @@ public void EnsureFailureOnReInitializingExistingConfig()
         [DataRow("StaticWebApps", null, null, DisplayName = "StaticWebApps with no audience and no issuer specified.")]
         [DataRow("AppService", null, null, DisplayName = "AppService with no audience and no issuer specified.")]
         [DataRow("Simulator", null, null, DisplayName = "Simulator with no audience and no issuer specified.")]
+        [DataRow("Unauthenticated", null, null, DisplayName = "Unauthenticated with no audience and no issuer specified.")]
         [DataRow("AzureAD", "aud-xxx", "issuer-xxx", DisplayName = "AzureAD with both audience and issuer specified.")]
         [DataRow("EntraID", "aud-xxx", "issuer-xxx", DisplayName = "EntraID with both audience and issuer specified.")]
         public Task EnsureCorrectConfigGenerationWithDifferentAuthenticationProviders(

src/Cli.Tests/Snapshots/InitTests.EnsureCorrectConfigGenerationWithDifferentAuthenticationProviders_47836da0dfbdc458.verified.txt

@@ -0,0 +1,50 @@
+{
+  DataSource: {
+    DatabaseType: MSSQL,
+    Options: {
+      set-session-context: false
+    }
+  },
+  Runtime: {
+    Rest: {
+      Enabled: true,
+      Path: /api,
+      RequestBodyStrict: true
+    },
+    GraphQL: {
+      Enabled: true,
+      Path: /graphql,
+      AllowIntrospection: true
+    },
+    Mcp: {
+      Enabled: true,
+      Path: /mcp,
+      DmlTools: {
+        AllToolsEnabled: true,
+        DescribeEntities: true,
+        CreateRecord: true,
+        ReadRecords: true,
+        UpdateRecord: true,
+        DeleteRecord: true,
+        ExecuteEntity: true,
+        UserProvidedAllTools: false,
+        UserProvidedDescribeEntities: false,
+        UserProvidedCreateRecord: false,
+        UserProvidedReadRecords: false,
+        UserProvidedUpdateRecord: false,
+        UserProvidedDeleteRecord: false,
+        UserProvidedExecuteEntity: false
+      }
+    },
+    Host: {
+      Cors: {
+        AllowCredentials: false
+      },
+      Authentication: {
+        Provider: Unauthenticated
+      },
+      Mode: Production
+    }
+  },
+  Entities: []
+}

src/Cli.Tests/ValidateConfigTests.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT License.
 
+using Azure.DataApiBuilder.Config.ObjectModel;
 using Azure.DataApiBuilder.Core.Configurations;
 using Azure.DataApiBuilder.Core.Models;
 using Serilog;
@@ -359,4 +360,36 @@ private async Task ValidatePropertyOptionsFails(ConfigureOptions options)
         JsonSchemaValidationResult result = await validator.ValidateConfigSchema(config, TEST_RUNTIME_CONFIG_FILE, mockLoggerFactory.Object);
         Assert.IsFalse(result.IsValid);
     }
+
+    /// <summary>
+    /// Test that the Unauthenticated provider is correctly identified by the IsUnauthenticatedAuthenticationProvider method.
+    /// </summary>
+    [TestMethod]
+    public void TestIsUnauthenticatedAuthenticationProviderMethod()
+    {
+        // Test with Unauthenticated provider
+        AuthenticationOptions unauthenticatedOptions = new(Provider: "Unauthenticated");
+        Assert.IsTrue(unauthenticatedOptions.IsUnauthenticatedAuthenticationProvider());
+
+        // Test case-insensitivity
+        AuthenticationOptions unauthenticatedOptionsLower = new(Provider: "unauthenticated");
+        Assert.IsTrue(unauthenticatedOptionsLower.IsUnauthenticatedAuthenticationProvider());
+
+        // Test that other providers are not identified as Unauthenticated
+        AuthenticationOptions appServiceOptions = new(Provider: "AppService");
+        Assert.IsFalse(appServiceOptions.IsUnauthenticatedAuthenticationProvider());
+
+        AuthenticationOptions simulatorOptions = new(Provider: "Simulator");
+        Assert.IsFalse(simulatorOptions.IsUnauthenticatedAuthenticationProvider());
+    }
+
+    /// <summary>
+    /// Test that Unauthenticated provider does not require JWT configuration.
+    /// </summary>
+    [TestMethod]
+    public void TestUnauthenticatedProviderDoesNotRequireJwt()
+    {
+        AuthenticationOptions unauthenticatedOptions = new(Provider: "Unauthenticated");
+        Assert.IsFalse(unauthenticatedOptions.IsJwtConfiguredIdentityProvider());
+    }
 }

src/Cli/ConfigGenerator.cs

@@ -2444,6 +2444,28 @@ public static bool IsConfigValid(ValidateOptions options, FileSystemRuntimeConfi
                             }
                         }
                     }
+
+                    // Warn if Unauthenticated provider is used with authenticated or custom roles
+                    if (config.Runtime?.Host?.Authentication?.IsUnauthenticatedAuthenticationProvider() == true)
+                    {
+                        foreach (KeyValuePair<string, Entity> entity in config.Entities)
+                        {
+                            if (entity.Value.Permissions is not null)
+                            {
+                                foreach (EntityPermission permission in entity.Value.Permissions)
+                                {
+                                    if (!permission.Role.Equals("anonymous", StringComparison.OrdinalIgnoreCase))
+                                    {
+                                        _logger.LogWarning(
+                                            "Entity '{EntityName}' has permission configured for role '{Role}' but authentication provider is 'Unauthenticated'. " +
+                                            "All requests will be treated as anonymous.",
+                                            entity.Key,
+                                            permission.Role);
+                                    }
+                                }
+                            }
+                        }
+                    }
                 }
             }
 

src/Cli/Utils.cs

@@ -516,19 +516,20 @@ public static bool ValidateAudienceAndIssuerForJwtProvider(
             string? issuer)
         {
             if (Enum.TryParse<EasyAuthType>(authenticationProvider, ignoreCase: true, out _)
-                || AuthenticationOptions.SIMULATOR_AUTHENTICATION == authenticationProvider)
+                || AuthenticationOptions.SIMULATOR_AUTHENTICATION == authenticationProvider
+                || AuthenticationOptions.UNAUTHENTICATED_AUTHENTICATION.Equals(authenticationProvider, StringComparison.OrdinalIgnoreCase))
             {
                 if (!(string.IsNullOrWhiteSpace(audience)) || !(string.IsNullOrWhiteSpace(issuer)))
                 {
-                    _logger.LogWarning("Audience and Issuer can't be set for EasyAuth or Simulator authentication.");
+                    _logger.LogWarning("Audience and Issuer can't be set for EasyAuth, Simulator, or Unauthenticated authentication.");
                     return true;
                 }
             }
             else
             {
                 if (string.IsNullOrWhiteSpace(audience) || string.IsNullOrWhiteSpace(issuer))
                 {
-                    _logger.LogError($"Authentication providers other than EasyAuth and Simulator require both Audience and Issuer.");
+                    _logger.LogError($"Authentication providers other than EasyAuth, Simulator, and Unauthenticated require both Audience and Issuer.");
                     return false;
                 }
             }

src/Config/ObjectModel/AuthenticationOptions.cs

@@ -32,9 +32,17 @@ public record AuthenticationOptions(string Provider = nameof(EasyAuthType.AppSer
     /// <returns>True when development mode should authenticate all requests.</returns>
     public bool IsAuthenticationSimulatorEnabled() => Provider.Equals(SIMULATOR_AUTHENTICATION, StringComparison.OrdinalIgnoreCase);
 
+    public const string UNAUTHENTICATED_AUTHENTICATION = "Unauthenticated";
+
+    /// <summary>
+    /// Returns whether the configured Provider value matches the unauthenticated authentication type.
+    /// </summary>
+    /// <returns>True when all operations run as anonymous.</returns>
+    public bool IsUnauthenticatedAuthenticationProvider() => Provider.Equals(UNAUTHENTICATED_AUTHENTICATION, StringComparison.OrdinalIgnoreCase);
+
     /// <summary>
     /// A shorthand method to determine whether JWT is configured for the current authentication provider.
     /// </summary>
     /// <returns>True if the provider is enabled for JWT, otherwise false.</returns>
-    public bool IsJwtConfiguredIdentityProvider() => !IsEasyAuthAuthenticationProvider() && !IsAuthenticationSimulatorEnabled();
+    public bool IsJwtConfiguredIdentityProvider() => !IsEasyAuthAuthenticationProvider() && !IsAuthenticationSimulatorEnabled() && !IsUnauthenticatedAuthenticationProvider();
 };

src/Core/AuthenticationHelpers/SupportedAuthNProviders.cs

@@ -14,4 +14,6 @@ internal static class SupportedAuthNProviders
     public const string SIMULATOR = "Simulator";
 
     public const string STATIC_WEB_APPS = "StaticWebApps";
+
+    public const string UNAUTHENTICATED = "Unauthenticated";
 }

src/Core/AuthenticationHelpers/UnauthenticatedAuthenticationHandler/UnauthenticatedAuthenticationBuilderExtensions.cs

@@ -0,0 +1,34 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Microsoft.AspNetCore.Authentication;
+
+namespace Azure.DataApiBuilder.Core.AuthenticationHelpers.UnauthenticatedAuthenticationHandler;
+
+/// <summary>
+/// Extension methods related to Unauthenticated authentication.
+/// This class allows setting up Unauthenticated authentication in the startup class with
+/// a single call to .AddAuthentication(scheme).AddUnauthenticatedAuthentication()
+/// </summary>
+public static class UnauthenticatedAuthenticationBuilderExtensions
+{
+    /// <summary>
+    /// Add authentication with Unauthenticated provider.
+    /// </summary>
+    /// <param name="builder">Authentication builder.</param>
+    /// <returns>The builder, to chain commands.</returns>
+    public static AuthenticationBuilder AddUnauthenticatedAuthentication(this AuthenticationBuilder builder)
+    {
+        if (builder is null)
+        {
+            throw new System.ArgumentNullException(nameof(builder));
+        }
+
+        builder.AddScheme<AuthenticationSchemeOptions, UnauthenticatedAuthenticationHandler>(
+            authenticationScheme: UnauthenticatedAuthenticationDefaults.AUTHENTICATIONSCHEME,
+            displayName: UnauthenticatedAuthenticationDefaults.AUTHENTICATIONSCHEME,
+            configureOptions: null);
+
+        return builder;
+    }
+}

src/Core/AuthenticationHelpers/UnauthenticatedAuthenticationHandler/UnauthenticatedAuthenticationDefaults.cs

@@ -0,0 +1,15 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+namespace Azure.DataApiBuilder.Core.AuthenticationHelpers.UnauthenticatedAuthenticationHandler;
+
+/// <summary>
+/// Default values related to UnauthenticatedAuthentication handler.
+/// </summary>
+public static class UnauthenticatedAuthenticationDefaults
+{
+    /// <summary>
+    /// The default value used for UnauthenticatedAuthenticationOptions.AuthenticationScheme.
+    /// </summary>
+    public const string AUTHENTICATIONSCHEME = "UnauthenticatedAuthentication";
+}

src/Core/AuthenticationHelpers/UnauthenticatedAuthenticationHandler/UnauthenticatedAuthenticationHandler.cs

@@ -0,0 +1,49 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System.Security.Claims;
+using System.Text.Encodings.Web;
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+
+namespace Azure.DataApiBuilder.Core.AuthenticationHelpers.UnauthenticatedAuthenticationHandler;
+
+/// <summary>
+/// This class is used to best integrate with ASP.NET Core AuthenticationHandler base class.
+/// When "Unauthenticated" is configured, this handler authenticates the user as anonymous,
+/// without reading any HTTP authentication headers.
+/// </summary>
+public class UnauthenticatedAuthenticationHandler : AuthenticationHandler<AuthenticationSchemeOptions>
+{
+    /// <summary>
+    /// Constructor for the UnauthenticatedAuthenticationHandler.
+    /// Note the parameters are required by the base class.
+    /// </summary>
+    /// <param name="options">Authentication options.</param>
+    /// <param name="logger">Logger factory.</param>
+    /// <param name="encoder">URL encoder.</param>
+    public UnauthenticatedAuthenticationHandler(
+        IOptionsMonitor<AuthenticationSchemeOptions> options,
+        ILoggerFactory logger,
+        UrlEncoder encoder)
+        : base(options, logger, encoder)
+    {
+    }
+
+    /// <summary>
+    /// Returns an unauthenticated ClaimsPrincipal for all requests.
+    /// The ClaimsPrincipal has no identity and no claims, representing an anonymous user.
+    /// </summary>
+    /// <returns>An authentication result to ASP.NET Core library authentication mechanisms</returns>
+    protected override Task<AuthenticateResult> HandleAuthenticateAsync()
+    {
+        // ClaimsIdentity without authenticationType means the user is not authenticated (anonymous)
+        ClaimsIdentity identity = new();
+        ClaimsPrincipal claimsPrincipal = new(identity);
+
+        AuthenticationTicket ticket = new(claimsPrincipal, UnauthenticatedAuthenticationDefaults.AUTHENTICATIONSCHEME);
+        AuthenticateResult success = AuthenticateResult.Success(ticket);
+        return Task.FromResult(success);
+    }
+}

src/Service/Startup.cs

@@ -13,6 +13,7 @@
 using Azure.DataApiBuilder.Config.Utilities;
 using Azure.DataApiBuilder.Core.AuthenticationHelpers;
 using Azure.DataApiBuilder.Core.AuthenticationHelpers.AuthenticationSimulator;
+using Azure.DataApiBuilder.Core.AuthenticationHelpers.UnauthenticatedAuthenticationHandler;
 using Azure.DataApiBuilder.Core.Authorization;
 using Azure.DataApiBuilder.Core.Configurations;
 using Azure.DataApiBuilder.Core.Models;
@@ -772,7 +773,7 @@ private void ConfigureAuthentication(IServiceCollection services, RuntimeConfigP
             {
                 AuthenticationOptions authOptions = runtimeConfig.Runtime.Host.Authentication;
                 HostMode mode = runtimeConfig.Runtime.Host.Mode;
-                if (!authOptions.IsAuthenticationSimulatorEnabled() && !authOptions.IsEasyAuthAuthenticationProvider())
+                if (!authOptions.IsAuthenticationSimulatorEnabled() && !authOptions.IsEasyAuthAuthenticationProvider() && !authOptions.IsUnauthenticatedAuthenticationProvider())
                 {
                     services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
                     .AddJwtBearer(options =>
@@ -809,6 +810,11 @@ private void ConfigureAuthentication(IServiceCollection services, RuntimeConfigP
                     _logger.LogInformation("Registered EasyAuth scheme: {Scheme}", defaultScheme);
 
                 }
+                else if (authOptions.IsUnauthenticatedAuthenticationProvider())
+                {
+                    services.AddAuthentication(UnauthenticatedAuthenticationDefaults.AUTHENTICATIONSCHEME)
+                        .AddUnauthenticatedAuthentication();
+                }
                 else if (mode == HostMode.Development && authOptions.IsAuthenticationSimulatorEnabled())
                 {
                     services.AddAuthentication(SimulatorAuthenticationDefaults.AUTHENTICATIONSCHEME)
@@ -850,7 +856,8 @@ private static void ConfigureAuthenticationV2(IServiceCollection services, Runti
             services.AddAuthentication()
                     .AddEnvDetectedEasyAuth()
                     .AddJwtBearer()
-                    .AddSimulatorAuthentication();
+                    .AddSimulatorAuthentication()
+                    .AddUnauthenticatedAuthentication();
         }
 
         /// <summary>