Exclude Aspire service discovery resolver from internal HttpClient used by Eureka (#1598)

Author: bart-vmware

src/Discovery/src/Eureka/EurekaServiceCollectionExtensions.cs

@@ -20,6 +20,7 @@ namespace Steeltoe.Discovery.Eureka;
 public static class EurekaServiceCollectionExtensions
 {
     private const string SpringDiscoveryEnabled = "spring:cloud:discovery:enabled";
+    private const string ResolvingHttpDelegatingHandlerName = "Microsoft.Extensions.ServiceDiscovery.Http.ResolvingHttpDelegatingHandler";
 
     /// <summary>
     /// Configures to use <see cref="EurekaDiscoveryClient" /> for service discovery.
@@ -108,7 +109,7 @@ private static void AddEurekaClient(IServiceCollection services)
         services.ConfigureCertificateOptions("Eureka");
 
         IHttpClientBuilder eurekaHttpClientBuilder = services.AddHttpClient("Eureka");
-        eurekaHttpClientBuilder.ConfigureAdditionalHttpMessageHandlers((defaultHandlers, _) => RemoveDiscoveryHttpDelegatingHandler(defaultHandlers));
+        eurekaHttpClientBuilder.ConfigureAdditionalHttpMessageHandlers((defaultHandlers, _) => RemoveDiscoveryHttpHandlers(defaultHandlers));
 
         eurekaHttpClientBuilder.ConfigurePrimaryHttpMessageHandler(serviceProvider =>
         {
@@ -122,7 +123,7 @@ private static void AddEurekaClient(IServiceCollection services)
         });
 
         IHttpClientBuilder eurekaTokenHttpClientBuilder = services.AddHttpClient("AccessTokenForEureka");
-        eurekaTokenHttpClientBuilder.ConfigureAdditionalHttpMessageHandlers((defaultHandlers, _) => RemoveDiscoveryHttpDelegatingHandler(defaultHandlers));
+        eurekaTokenHttpClientBuilder.ConfigureAdditionalHttpMessageHandlers((defaultHandlers, _) => RemoveDiscoveryHttpHandlers(defaultHandlers));
 
         eurekaTokenHttpClientBuilder.ConfigurePrimaryHttpMessageHandler(serviceProvider =>
         {
@@ -139,12 +140,19 @@ private static void AddEurekaClient(IServiceCollection services)
         services.AddSingleton<EurekaClient>();
     }
 
-    private static void RemoveDiscoveryHttpDelegatingHandler(ICollection<DelegatingHandler> defaultHandlers)
+    private static void RemoveDiscoveryHttpHandlers(ICollection<DelegatingHandler> defaultHandlers)
     {
+        // Prevent infinite recursion: The inner HttClient used by EurekaDiscoveryClient must not use service discovery.
+
         DelegatingHandler[] discoveryHandlers = defaultHandlers.Where(handler =>
         {
             Type handlerType = handler.GetType();
 
+            if (handlerType.FullName == ResolvingHttpDelegatingHandlerName)
+            {
+                return true;
+            }
+
             if (handlerType.IsConstructedGenericType)
             {
                 Type handlerOpenType = handlerType.GetGenericTypeDefinition();
@@ -160,7 +168,6 @@ private static void RemoveDiscoveryHttpDelegatingHandler(ICollection<DelegatingH
 
         foreach (DelegatingHandler discoveryHandler in discoveryHandlers)
         {
-            // Prevent infinite recursion: DiscoveryHttpDelegatingHandler depends on EurekaDiscoveryClient.
             defaultHandlers.Remove(discoveryHandler);
         }
     }

src/Discovery/test/HttpClients.Test/DiscoveryWebApplicationBuilderExtensionsTest.cs

@@ -7,7 +7,10 @@
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.ServiceDiscovery.Http;
+using RichardSzalay.MockHttp;
 using Steeltoe.Common.Discovery;
+using Steeltoe.Common.Http.HttpClientPooling;
 using Steeltoe.Common.TestResources;
 using Steeltoe.Discovery.Consul;
 using Steeltoe.Discovery.Eureka;
@@ -77,4 +80,34 @@ public async Task AddEurekaDiscoveryClient_WorksWithGlobalServiceDiscovery()
 
         await action.Should().NotThrowAsync();
     }
+
+    [Fact]
+    public async Task AddEurekaDiscoveryClient_WorksWithAspireGlobalServiceDiscovery()
+    {
+        WebApplicationBuilder builder = TestWebApplicationBuilderFactory.Create();
+
+        builder.Configuration.AddInMemoryCollection(new Dictionary<string, string?>
+        {
+            ["Eureka:Client:ShouldFetchRegistry"] = "false",
+            ["Eureka:Client:ShouldRegisterWithEureka"] = "false"
+        });
+
+        builder.Services.AddEurekaDiscoveryClient();
+        builder.Services.AddTransient<ResolvingHttpDelegatingHandler>();
+        builder.Services.ConfigureHttpClientDefaults(action => action.AddHttpMessageHandler<ResolvingHttpDelegatingHandler>());
+
+        var handler = new DelegateToMockHttpClientHandler();
+        handler.Mock.Expect(HttpMethod.Get, "http://localhost:8761/eureka/apps").Respond("application/json", "{}");
+
+        await using WebApplication host = builder.Build();
+
+        host.Services.GetRequiredService<HttpClientHandlerFactory>().Using(handler);
+
+        var discoveryClient = host.Services.GetRequiredService<EurekaDiscoveryClient>();
+        Func<Task> action = async () => await discoveryClient.FetchRegistryAsync(true, TestContext.Current.CancellationToken);
+
+        await action.Should().NotThrowAsync();
+
+        handler.Mock.VerifyNoOutstandingExpectation();
+    }
 }

src/Discovery/test/HttpClients.Test/ResolvingHttpDelegatingHandler.cs

@@ -0,0 +1,16 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the Apache 2.0 License.
+// See the LICENSE file in the project root for more information.
+
+#pragma warning disable IDE0130 // Namespace does not match folder structure
+// ReSharper disable once CheckNamespace
+namespace Microsoft.Extensions.ServiceDiscovery.Http;
+#pragma warning restore IDE0130 // Namespace does not match folder structure
+
+internal sealed class ResolvingHttpDelegatingHandler : DelegatingHandler
+{
+    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+    {
+        throw new InvalidOperationException("This handler should have been removed from the HttpClient pipeline.");
+    }
+}