YARP–Direct forwarding in .NET 6 and beyond

With YARP(Yet-Another-Reverse-Proxy) you can transform your ASP.NET Core application into a reverse proxy.

It offers features like routing, discovery, load balancing, retries,... However in the application I'm building that is a lot more then what I need. I only need the ability to take a specific request and forward it to a specific destination. In that case you can use Direct Forwarding through the IHttpForwarder.

IHttpForwarder supports:

• Dynamic destination selection, you specify the destination for each request
• Http client customization, you provide the HttpMessageInvoker
• Request and response customization (except bodies)
• Streaming protocols like gRPC and WebSockets
• Error handling

It does not include:

• Routing
• Load balancing
• Affinity
• Retries

Direct forwarding in .NET 6 and beyond

You can find an example of Direct Forwarding in the documentation. However this documentation is written for .NET 5 still using the Startup.cs class.

Let me share an example on how to achieve the same thing in .NET 6:

	using System.Diagnostics;
	using System.Net;
	using Yarp.ReverseProxy.Forwarder;
	var builder = WebApplication.CreateBuilder(args);
	var targetUrl = builder.Configuration.GetValue<string>("targetUrl");
	builder.Services.AddHttpForwarder();
	var app = builder.Build();
	app.UseRouting();
	//Always use HttpMessageInvoker rather than HttpClient, HttpClient buffers responses by default.
	//Buffering breaks streaming scenarios and increases memory usage and latency.
	var httpClient = new HttpMessageInvoker(new SocketsHttpHandler()
	{
	UseProxy = false,
	AllowAutoRedirect = false,
	AutomaticDecompression = DecompressionMethods.None,
	UseCookies = false,
	ActivityHeadersPropagator = new ReverseProxyPropagator(DistributedContextPropagator.Current)
	});
	var requestConfig = new ForwarderRequestConfig { ActivityTimeout = TimeSpan.FromSeconds(100) };
	app.Map("/{**catch-all}", async (HttpContext httpContext, IHttpForwarder forwarder) => {
	var error = await forwarder.SendAsync(httpContext, targetUrl, httpClient, requestConfig);
	// Check if the operation was successful
	if (error != ForwarderError.None)
	{
	var errorFeature = httpContext.GetForwarderErrorFeature();
	var exception = errorFeature.Exception;
	//TODO: Log exception
	}
	});
	app.Run();

view raw Program.cs hosted with ❤ by GitHub

You can find the complete example here: https://github.com/wullemsb/YarpDirectForwarding