#740 #1580 Support multiple authentication schemes in one route

docs/features/authentication.rst

@@ -2,36 +2,91 @@ Authentication
 ==============
 
 In order to authenticate Routes and subsequently use any of Ocelot's claims based features such as authorization or modifying the request with values from the token,
-users must register authentication services in their **Startup.cs** as usual but they provide a scheme (authentication provider key) with each registration e.g.
+users must register authentication services in their **Startup.cs** as usual but they provide `a scheme <https://learn.microsoft.com/en-us/aspnet/core/security/authentication/#authentication-scheme>`_ 
+(authentication provider key) with each registration e.g.
 
 .. code-block:: csharp
 
     public void ConfigureServices(IServiceCollection services)
     {
-        var authenticationProviderKey = "TestKey";
+        const string AuthenticationProviderKey = "MyKey";
         services
             .AddAuthentication()
-            .AddJwtBearer(authenticationProviderKey,
-                options => { /* custom auth-setup */ });
+            .AddJwtBearer(AuthenticationProviderKey, options =>
+            {
+                // Custom Authentication setup via options initialization
+            });
     }
 
-In this example "**TestKey**" is the scheme that this provider has been registered with. We then map this to a Route in the configuration e.g.
+In this example ``MyKey`` is `the scheme <https://learn.microsoft.com/en-us/aspnet/core/security/authentication/#authentication-scheme>`_ that this provider has been registered with.
+We then map this to a Route in the configuration using the following `AuthenticationOptions <https://github.com/search?q=repo%3AThreeMammals%2FOcelot%20AuthenticationOptions&type=code>`_ properties:
+
+* ``AuthenticationProviderKey`` is a string object, obsolete. [#f1]_ This is legacy definition when you define :ref:`authentication-single` (scheme).
+* ``AuthenticationProviderKeys`` is an array of strings, the recommended definition of :ref:`authentication-multiple` feature.
+
+.. authentication-single:
+
+Single Key [#f1]_
+-----------------
+
+    | Property: ``AuthenticationOptions.AuthenticationProviderKey``
+
+We map authentication provider to a Route in the configuration e.g.
 
 .. code-block:: json
 
-  "Routes": [{
-    "AuthenticationOptions": {
-      "AuthenticationProviderKey": "TestKey",
-      "AllowedScopes": []
-    }
-  }]
+  "AuthenticationOptions": {
+    "AuthenticationProviderKey": "MyKey",
+    "AllowedScopes": []
+  }
 
-When Ocelot runs it will look at this Routes ``AuthenticationOptions.AuthenticationProviderKey`` and check that there is an authentication provider registered with the given key.
+When Ocelot runs it will look at this Routes ``AuthenticationProviderKey`` and check that there is an authentication provider registered with the given key.
 If there isn't then Ocelot will not start up. If there is then the Route will use that provider when it executes.
 
 If a Route is authenticated, Ocelot will invoke whatever scheme is associated with it while executing the authentication middleware.
 If the request fails authentication, Ocelot returns a HTTP status code `401 Unauthorized <https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/401>`_.
 
+.. authentication-multiple:
+
+Multiple Authentication Schemes [#f2]_
+--------------------------------------
+
+    | Property: ``AuthenticationOptions.AuthenticationProviderKeys``
+
+In real world of ASP.NET, apps may need to support multiple types of authentication by single Ocelot app instance.
+To register `multiple authentication schemes <https://learn.microsoft.com/en-us/aspnet/core/security/authorization/limitingidentitybyscheme#use-multiple-authentication-schemes>`_
+(authentication provider keys) for each appropriate authentication provider, use and develop this abstract configuration of two or more schemes:
+
+.. code-block:: csharp
+
+    public void ConfigureServices(IServiceCollection services)
+    {
+        const string DefaultScheme = JwtBearerDefaults.AuthenticationScheme; // Bearer
+        services.AddAuthentication()
+            .AddJwtBearer(DefaultScheme, options => { /* JWT setup */ })
+            // AddJwtBearer, AddCookie, AddIdentityServerAuthentication etc. 
+            .AddMyProvider("MyKey", options => { /* Custom auth setup */ });
+    }
+
+In this example, the schemes ``MyKey`` and ``Bearer`` represent the keys which these providers have been registered with.
+We then map these schemes to a Route in the configuration, as shown below
+
+.. code-block:: json
+
+  "AuthenticationOptions": {
+    "AuthenticationProviderKeys": [ "Bearer", "MyKey" ] // The order matters!
+    "AllowedScopes": []
+  }
+
+Afterward, Ocelot applies all steps that are specified for ``AuthenticationProviderKey`` as :ref:`authentication-single`.
+
+**Note** that the order of the keys in an array definition does matter! We use a "First One Wins" authentication strategy.
+
+Finally, we would say that registering providers, initializing options, forwarding authentication artifacts can be a "real" coding challenge.
+If you're stuck or don't know what to do, just find inspiration in our `acceptance tests <https://github.com/search?q=repo%3AThreeMammals%2FOcelot%20MultipleAuthSchemesFeatureTests&type=code>`_ 
+(currently for `Identity Server 4 <https://identityserver4.readthedocs.io/>`_ only).
+We would appreciate any new PRs to add extra acceptance tests for your custom scenarios with `multiple authentication schemes <https://learn.microsoft.com/en-us/aspnet/core/security/authorization/limitingidentitybyscheme#use-multiple-authentication-schemes>`__. [#f2]_
+
 JWT Tokens
 ----------
 
@@ -41,7 +96,7 @@ If you want to authenticate using JWT tokens maybe from a provider like `Auth0 <
 
     public void ConfigureServices(IServiceCollection services)
     {
-        var authenticationProviderKey = "TestKey";
+        var authenticationProviderKey = "MyKey";
         services
             .AddAuthentication()
             .AddJwtBearer(authenticationProviderKey, options =>
@@ -56,12 +111,16 @@ Then map the authentication provider key to a Route in your configuration e.g.
 
 .. code-block:: json
 
-  "Routes": [{
-    "AuthenticationOptions": {
-      "AuthenticationProviderKey": "TestKey",
-      "AllowedScopes": []
-    }
-  }]
+  "AuthenticationOptions": {
+    "AuthenticationProviderKeys": [ "MyKey" ],
+    "AllowedScopes": []
+  }
+
+Docs
+^^^^
+
+* Microsoft Learn: `Authentication and authorization in minimal APIs <https://learn.microsoft.com/en-us/aspnet/core/fundamentals/minimal-apis/security>`_
+* Andrew Lock | .NET Escapades: `A look behind the JWT bearer authentication middleware in ASP.NET Core <https://andrewlock.net/a-look-behind-the-jwt-bearer-authentication-middleware-in-asp-net-core/>`_
 
 Identity Server Bearer Tokens
 -----------------------------
@@ -73,7 +132,7 @@ If you don't understand how to do this, please consult the IdentityServer `docum
 
     public void ConfigureServices(IServiceCollection services)
     {
-        var authenticationProviderKey = "TestKey";
+        var authenticationProviderKey = "MyKey";
         Action<JwtBearerOptions> options = (opt) =>
         {
             opt.Authority = "https://whereyouridentityserverlives.com";
@@ -89,12 +148,10 @@ Then map the authentication provider key to a Route in your configuration e.g.
 
 .. code-block:: json
 
-  "Routes": [{
-    "AuthenticationOptions": {
-      "AuthenticationProviderKey": "TestKey",
-      "AllowedScopes": []
-    }
-  }]
+  "AuthenticationOptions": {
+    "AuthenticationProviderKeys": [ "MyKey" ],
+    "AllowedScopes": []
+  }
 
 Auth0 by Okta
 -------------
@@ -137,8 +194,21 @@ If you add scopes to **AllowedScopes**, Ocelot will get all the user claims (fro
 
 This is a way to restrict access to a Route on a per scope basis.
 
-More identity providers
------------------------
+Links
+-----
+
+* Microsoft Learn: `Overview of ASP.NET Core authentication <https://learn.microsoft.com/en-us/aspnet/core/security/authentication/>`_
+* Microsoft Learn: `Authorize with a specific scheme in ASP.NET Core <https://learn.microsoft.com/en-us/aspnet/core/security/authorization/limitingidentitybyscheme>`_
+* Microsoft Learn: `Policy schemes in ASP.NET Core <https://learn.microsoft.com/en-us/aspnet/core/security/authentication/policyschemes>`_
+* Microsoft .NET Blog: `ASP.NET Core Authentication with IdentityServer4 <https://devblogs.microsoft.com/dotnet/asp-net-core-authentication-with-identityserver4/>`_
+
+Future
+------
 
 We invite you to add more examples, if you have integrated with other identity providers and the integration solution is working.
 Please, open `Show and tell <https://github.com/ThreeMammals/Ocelot/discussions/categories/show-and-tell>`_ discussion in the repository.
+
+""""
+
+.. [#f1] Use the ``AuthenticationProviderKeys`` property instead of ``AuthenticationProviderKey`` one. We supports this obsolete property because of backward compatibility and allowing migrations. In future releases the property can be removed as a breaking change.
+.. [#f2] `Multiple authentication schemes <https://learn.microsoft.com/en-us/aspnet/core/security/authorization/limitingidentitybyscheme#use-multiple-authentication-schemes>`__ feature was requested in issues `740 <https://github.com/ThreeMammals/Ocelot/issues/740>`_, `1580 <https://github.com/ThreeMammals/Ocelot/issues/1580>`_ and delivered as a part of `23.0 <https://github.com/ThreeMammals/Ocelot/releases/tag/23.0.0>`_ release.

src/Ocelot/Authentication/Middleware/AuthenticationMiddleware.cs

@@ -6,55 +6,93 @@
 
 namespace Ocelot.Authentication.Middleware
 {
-    public class AuthenticationMiddleware : OcelotMiddleware
+    public sealed class AuthenticationMiddleware : OcelotMiddleware
     {
         private readonly RequestDelegate _next;
 
-        public AuthenticationMiddleware(RequestDelegate next,
-            IOcelotLoggerFactory loggerFactory)
+        public AuthenticationMiddleware(RequestDelegate next, IOcelotLoggerFactory loggerFactory)
             : base(loggerFactory.CreateLogger<AuthenticationMiddleware>())
         {
             _next = next;
         }
 
         public async Task Invoke(HttpContext httpContext)
         {
+            var request = httpContext.Request;
+            var path = httpContext.Request.Path;
             var downstreamRoute = httpContext.Items.DownstreamRoute();
 
-            if (httpContext.Request.Method.ToUpper() != "OPTIONS" && IsAuthenticatedRoute(downstreamRoute))
+            // reducing nesting, returning early when no authentication is needed.
+            if (request.Method.Equals("OPTIONS", StringComparison.OrdinalIgnoreCase) || !downstreamRoute.IsAuthenticated)
             {
-                Logger.LogInformation(() => $"{httpContext.Request.Path} is an authenticated route. {MiddlewareName} checking if client is authenticated");
+                Logger.LogInformation($"No authentication needed for path '{path}'.");
+                await _next(httpContext);
+                return;
+            }
 
-                var result = await httpContext.AuthenticateAsync(downstreamRoute.AuthenticationOptions.AuthenticationProviderKey);
+            Logger.LogInformation(() => $"The path '{path}' is an authenticated route! {MiddlewareName} checking if client is authenticated...");
 
-                httpContext.User = result.Principal;
+            var result = await AuthenticateAsync(httpContext, downstreamRoute);
 
-                if (httpContext.User.Identity.IsAuthenticated)
-                {
-                    Logger.LogInformation(() => $"Client has been authenticated for {httpContext.Request.Path}");
-                    await _next.Invoke(httpContext);
-                }
-                else
-                {
-                    var error = new UnauthenticatedError(
-                        $"Request for authenticated route {httpContext.Request.Path} by {httpContext.User.Identity.Name} was unauthenticated");
+            if (result.Principal?.Identity == null)
+            {
+                SetUnauthenticatedError(httpContext, path, null);
+                return;
+            }
 
-                    Logger.LogWarning(() =>$"Client has NOT been authenticated for {httpContext.Request.Path} and pipeline error set. {error}");
+            httpContext.User = result.Principal;
 
-                    httpContext.Items.SetError(error);
-                }
-            }
-            else
+            if (httpContext.User.Identity.IsAuthenticated)
             {
-                Logger.LogInformation(() => $"No authentication needed for {httpContext.Request.Path}");
-
+                Logger.LogInformation(() => $"Client has been authenticated for path '{path}' by '{httpContext.User.Identity.AuthenticationType}' scheme.");
                 await _next.Invoke(httpContext);
+                return;
             }
+
+            SetUnauthenticatedError(httpContext, path, httpContext.User.Identity.Name);
+        }
+
+        private void SetUnauthenticatedError(HttpContext httpContext, string path, string userName)
+        {
+            var error = new UnauthenticatedError($"Request for authenticated route '{path}' {(string.IsNullOrEmpty(userName) ? "was unauthenticated" : $"by '{userName}' was unauthenticated!")}");
+            Logger.LogWarning(() => $"Client has NOT been authenticated for path '{path}' and pipeline error set. {error};");
+            httpContext.Items.SetError(error);
         }
 
-        private static bool IsAuthenticatedRoute(DownstreamRoute route)
+        private async Task<AuthenticateResult> AuthenticateAsync(HttpContext context, DownstreamRoute route)
         {
-            return route.IsAuthenticated;
+            var options = route.AuthenticationOptions;
+            if (!string.IsNullOrWhiteSpace(options.AuthenticationProviderKey))
+            {
+                return await context.AuthenticateAsync(options.AuthenticationProviderKey);
+            }
+
+            var providerKeys = options.AuthenticationProviderKeys;
+            if (providerKeys.Length == 0 || providerKeys.All(string.IsNullOrWhiteSpace))
+            {
+                Logger.LogWarning(() => $"Impossible to authenticate client for path '{route.DownstreamPathTemplate}': both {nameof(options.AuthenticationProviderKey)} and {nameof(options.AuthenticationProviderKeys)} are empty but the {nameof(Configuration.AuthenticationOptions)} have defined.");
+                return AuthenticateResult.NoResult();
+            }
+
+            AuthenticateResult result = null;
+            foreach (var scheme in providerKeys.Where(apk => !string.IsNullOrWhiteSpace(apk)))
+            {
+                try
+                {
+                    result = await context.AuthenticateAsync(scheme);
+                    if (result?.Succeeded == true)
+                    {
+                        return result;
+                    }
+                }
+                catch (Exception e)
+                {
+                    Logger.LogWarning(() =>
+                        $"Impossible to authenticate client for path '{route.DownstreamPathTemplate}' and {nameof(options.AuthenticationProviderKey)}:{scheme}. Error: {e.Message}.");
+                }
+            }
+
+            return result ?? AuthenticateResult.NoResult();
         }
     }
 }

src/Ocelot/Authentication/Middleware/AuthenticationMiddlewareExtensions.cs

@@ -0,0 +1,11 @@
+using Microsoft.AspNetCore.Builder;
+
+namespace Ocelot.Authentication.Middleware;
+
+public static class AuthenticationMiddlewareExtensions
+{
+    public static IApplicationBuilder UseAuthenticationMiddleware(this IApplicationBuilder builder)
+    {
+        return builder.UseMiddleware<AuthenticationMiddleware>();
+    }
+}

src/Ocelot/Configuration/AuthenticationOptions.cs

@@ -1,14 +1,51 @@
-namespace Ocelot.Configuration
-{
-    public class AuthenticationOptions
-    {
-        public AuthenticationOptions(List<string> allowedScopes, string authenticationProviderKey)
-        {
-            AllowedScopes = allowedScopes;
-            AuthenticationProviderKey = authenticationProviderKey;
-        }
-
-        public List<string> AllowedScopes { get; }
-        public string AuthenticationProviderKey { get; }
-    }
+using Ocelot.Configuration.File;
+
+namespace Ocelot.Configuration
+{
+    public sealed class AuthenticationOptions
+    {
+        public AuthenticationOptions(List<string> allowedScopes, string authenticationProviderKey)
+        {
+            AllowedScopes = allowedScopes;
+            AuthenticationProviderKey = authenticationProviderKey;
+            AuthenticationProviderKeys = [];
+        }
+
+        public AuthenticationOptions(FileAuthenticationOptions from)
+        {
+            AllowedScopes = from.AllowedScopes ?? [];
+            AuthenticationProviderKey = from.AuthenticationProviderKey ?? string.Empty;
+            AuthenticationProviderKeys = from.AuthenticationProviderKeys ?? [];
+        }
+
+        public AuthenticationOptions(List<string> allowedScopes, string authenticationProviderKey,
+            string[] authenticationProviderKeys)
+        {
+            AllowedScopes = allowedScopes ?? [];
+            AuthenticationProviderKey = authenticationProviderKey ?? string.Empty;
+            AuthenticationProviderKeys = authenticationProviderKeys ?? [];
+        }
+
+        public List<string> AllowedScopes { get; }
+
+        /// <summary>
+        /// Authentication scheme registered in DI services with appropriate authentication provider.
+        /// </summary>
+        /// <value>
+        /// A <see langword="string"/> value of the scheme name.
+        /// </value>
+        [Obsolete("Use the " + nameof(AuthenticationProviderKeys) + " property!")]
+        public string AuthenticationProviderKey { get; }
+
+        /// <summary>
+        /// Multiple authentication schemes registered in DI services with appropriate authentication providers.
+        /// </summary>
+        /// <remarks>
+        /// The order in the collection matters: first successful authentication result wins.
+        /// </remarks>
+        /// <value>
+        /// An array of <see langword="string"/> values of the scheme names.
+        /// </value>
+        public string[] AuthenticationProviderKeys { get; }
+    }
 }