Configuring HttpClient for Multiple Base Addresses in C# 10 - implementing Custom Handlers
I've been researching this but Quick question that's been bugging me - I'm currently working on a C# 10 application that needs to make HTTP calls to different services, each requiring distinct base addresses and custom headers. I'm using `HttpClientFactory` to manage these instances and looking to configure multiple `HttpClient` instances, but I'm working with issues where the custom handler setup seems to interfere with the base addresses. Here’s what I have so far: ```csharp public class MyHttpClientHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { // Custom logic before sending the request return await base.SendAsync(request, cancellationToken); } } public void ConfigureServices(IServiceCollection services) { services.AddHttpClient("ServiceA", c => { c.BaseAddress = new Uri("https://api.servicea.com/"); c.DefaultRequestHeaders.Add("Custom-Header-A", "ValueA"); }) .AddHttpMessageHandler<MyHttpClientHandler>(); services.AddHttpClient("ServiceB", c => { c.BaseAddress = new Uri("https://api.serviceb.com/"); c.DefaultRequestHeaders.Add("Custom-Header-B", "ValueB"); }) .AddHttpMessageHandler<MyHttpClientHandler>(); } ``` When I try to send requests to either service, I get the following behavior message intermittently: ``` System.Net.Http.HttpRequestException: Response status code does not indicate success: 404 (Not Found). ``` After examining the request, it appears that the base address isn't being set correctly for certain requests. When I debug, I notice that the `BaseAddress` is sometimes reverting to a previous value. I've also checked that my `ConfigureServices` method is being called only once during application startup. I'm not sure what I'm doing wrong or how to ensure that each `HttpClient` instance is isolated and uses the correct base address consistently. Any insights on how to properly configure multiple `HttpClient` instances with unique settings and avoid the 404 errors would be greatly appreciated. This is part of a larger service I'm building. Thanks in advance!