Fixed: SentryHttpMessageHandler added when AddHttpClient is before UseSentry (#2390)

* Fixed #2373: SentryHttpMessageHandler not being added when AddHttpClient is before UseSentry

Fixes #2373

* Updated changelog

Author: jamescrosswell

CHANGELOG.md

@@ -2,8 +2,9 @@
 
 ## Unreleased
 
-## Fixes
+### Fixes
 
+- SentryHttpMessageHandler added when AddHttpClient is before UseSentry ([#2390](https://github.com/getsentry/sentry-dotnet/pull/2390))
 - Set the native sdk name for Android ([#2389](https://github.com/getsentry/sentry-dotnet/pull/2389))
 
 ## 3.33.0

src/Sentry.Extensions.Logging/Extensions/DependencyInjection/ServiceCollectionExtensions.cs

@@ -40,7 +40,8 @@ public static IServiceCollection AddSentry<TOptions>(this IServiceCollection ser
 
         // Custom handler for HttpClientFactory.
         // Must be singleton: https://github.com/getsentry/sentry-dotnet/issues/785
-        services.TryAddSingleton<IHttpMessageHandlerBuilderFilter, SentryHttpMessageHandlerBuilderFilter>();
+        // Must use AddSingleton: https://github.com/getsentry/sentry-dotnet/issues/2373
+        services.AddSingleton<IHttpMessageHandlerBuilderFilter, SentryHttpMessageHandlerBuilderFilter>();
 
         return services;
     }

src/Sentry.Extensions.Logging/SentryHttpMessageHandlerBuilderFilter.cs

@@ -14,7 +14,13 @@ public Action<HttpMessageHandlerBuilder> Configure(Action<HttpMessageHandlerBuil
         handlerBuilder =>
         {
             var hub = _getHub();
-            handlerBuilder.AdditionalHandlers.Add(new SentryHttpMessageHandler(hub));
+            if (!handlerBuilder.AdditionalHandlers.Any(h => h is SentryHttpMessageHandler))
+            {
+                handlerBuilder.AdditionalHandlers.Add(
+                    new SentryHttpMessageHandler(hub)
+                );
+            }
+
             next(handlerBuilder);
         };
 }