From 62916d07ee1c935bf7daa728621db2877db9f222 Mon Sep 17 00:00:00 2001
From: Kahbazi <A.Kahbazi@gmail.com>
Date: Fri, 15 Jul 2022 13:16:11 +0430
Subject: [PATCH 1/3] Throw an exception in ConfigureHttpClient when custom
 IForwarderHttpClientFactory is added

---
 ...ReverseProxyServiceCollectionExtensions.cs | 10 ++++
 .../ReverseProxyServiceCollectionTests.cs     | 49 +++++++++++++++++++
 2 files changed, 59 insertions(+)
 create mode 100644 test/ReverseProxy.Tests/Forwarder/ReverseProxyServiceCollectionTests.cs

diff --git a/src/ReverseProxy/Management/ReverseProxyServiceCollectionExtensions.cs b/src/ReverseProxy/Management/ReverseProxyServiceCollectionExtensions.cs
index 63ceccc6a..5a77e3a0e 100644
--- a/src/ReverseProxy/Management/ReverseProxyServiceCollectionExtensions.cs
+++ b/src/ReverseProxy/Management/ReverseProxyServiceCollectionExtensions.cs
@@ -2,6 +2,7 @@
 // Licensed under the MIT License.
 
 using System;
+using System.Linq;
 using System.Net.Http;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection.Extensions;
@@ -143,6 +144,15 @@ public static IReverseProxyBuilder ConfigureHttpClient(this IReverseProxyBuilder
             throw new ArgumentNullException(nameof(configure));
         }
 
+        var service = builder.Services.FirstOrDefault(service => service.ServiceType == typeof(IForwarderHttpClientFactory));
+        if (service is not null)
+        {
+            if (service.ImplementationType != typeof(ForwarderHttpClientFactory))
+            {
+                throw new InvalidOperationException($"ConfigureHttpClient will override the custom IForwarderHttpClientFactory type.");
+            }
+        }
+
         builder.Services.AddSingleton<IForwarderHttpClientFactory>(services =>
         {
             var logger = services.GetRequiredService<ILogger<ForwarderHttpClientFactory>>();
diff --git a/test/ReverseProxy.Tests/Forwarder/ReverseProxyServiceCollectionTests.cs b/test/ReverseProxy.Tests/Forwarder/ReverseProxyServiceCollectionTests.cs
new file mode 100644
index 000000000..980e88de1
--- /dev/null
+++ b/test/ReverseProxy.Tests/Forwarder/ReverseProxyServiceCollectionTests.cs
@@ -0,0 +1,49 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using System;
+using System.Collections.Generic;
+using System.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Moq;
+using Xunit;
+using Yarp.Tests.Common;
+using Yarp.ReverseProxy.Configuration;
+using Yarp.ReverseProxy.Model;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Yarp.ReverseProxy.Forwarder;
+
+public class ReverseProxyServiceCollectionTests
+{
+
+    [Fact]
+    public void ConfigureHttpClient_Works()
+    {
+        new ServiceCollection()
+            .AddReverseProxy()
+            .ConfigureHttpClient((_, _) => { });
+    }
+
+    [Fact] 
+    public void ConfigureHttpClient_ThrowIfCustomServiceAdded()
+    {
+        Assert.Throws<InvalidOperationException>(() =>
+        {
+            new ServiceCollection()
+                .AddSingleton<IForwarderHttpClientFactory, CustomForwarderHttpClientFactory>()
+                .AddReverseProxy()
+                .ConfigureHttpClient((_, _) => { });
+        });
+    }
+
+    private class CustomForwarderHttpClientFactory : IForwarderHttpClientFactory
+    {
+        public HttpMessageInvoker CreateClient(ForwarderHttpClientContext context)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

From dd4275a0186cd96c2c537ea9c96281732e6f9539 Mon Sep 17 00:00:00 2001
From: Kahbazi <A.Kahbazi@gmail.com>
Date: Fri, 15 Jul 2022 15:17:09 +0430
Subject: [PATCH 2/3] Remove unused usings

---
 .../Forwarder/ReverseProxyServiceCollectionTests.cs    | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/test/ReverseProxy.Tests/Forwarder/ReverseProxyServiceCollectionTests.cs b/test/ReverseProxy.Tests/Forwarder/ReverseProxyServiceCollectionTests.cs
index 980e88de1..7e6c254fe 100644
--- a/test/ReverseProxy.Tests/Forwarder/ReverseProxyServiceCollectionTests.cs
+++ b/test/ReverseProxy.Tests/Forwarder/ReverseProxyServiceCollectionTests.cs
@@ -2,17 +2,9 @@
 // Licensed under the MIT License.
 
 using System;
-using System.Collections.Generic;
-using System.Net;
 using System.Net.Http;
-using System.Threading.Tasks;
-using Microsoft.AspNetCore.Http;
-using Moq;
-using Xunit;
-using Yarp.Tests.Common;
-using Yarp.ReverseProxy.Configuration;
-using Yarp.ReverseProxy.Model;
 using Microsoft.Extensions.DependencyInjection;
+using Xunit;
 
 namespace Yarp.ReverseProxy.Forwarder;
 

From 198768402a50f31516f438c18df76e9debb40546 Mon Sep 17 00:00:00 2001
From: Chris Ross <Tratcher@Outlook.com>
Date: Thu, 18 Aug 2022 10:39:54 -0700
Subject: [PATCH 3/3] Update
 src/ReverseProxy/Management/ReverseProxyServiceCollectionExtensions.cs

---
 .../Management/ReverseProxyServiceCollectionExtensions.cs       | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/ReverseProxy/Management/ReverseProxyServiceCollectionExtensions.cs b/src/ReverseProxy/Management/ReverseProxyServiceCollectionExtensions.cs
index 5a77e3a0e..f4f233544 100644
--- a/src/ReverseProxy/Management/ReverseProxyServiceCollectionExtensions.cs
+++ b/src/ReverseProxy/Management/ReverseProxyServiceCollectionExtensions.cs
@@ -144,6 +144,8 @@ public static IReverseProxyBuilder ConfigureHttpClient(this IReverseProxyBuilder
             throw new ArgumentNullException(nameof(configure));
         }
 
+        // Avoid overriding any other custom factories. This does not handle the case where a IForwarderHttpClientFactory
+        // is registered after this call.
         var service = builder.Services.FirstOrDefault(service => service.ServiceType == typeof(IForwarderHttpClientFactory));
         if (service is not null)
         {