YARP Supported Runtimes

YARP 1.1 supports ASP.NET Core 3.1, 5.0 and 6.0. You can download the .NET SDK from https://dotnet.microsoft.com/download/dotnet/. See Releases for specific version support.

YARP is taking advantage of ASP.NET Core 6.0 features and optimizations. This does mean that some features may not be available if you're running on the previous versions of ASP.NET.

Difference in features supported on .NET Core 3.1 vs .NET 5.0 and higher

Yarp.ReverseProxy package

The following features are supported on NET 5.0 and higher:

  • EnableMultipleHttp2Connections - enables opening additional HTTP/2 connections to the same server when the maximum number of concurrent streams is reached on all existing connections. Full path: ClusterConfig.HttpClient.EnableMultipleHttp2Connections. Type: bool?
  • RequestHeaderEncoding - allows to set a non-ASCII header encoding for outgoing requests. Full path: ClusterConfig.HttpClient.RequestHeaderEncoding. Type: string?
  • VersionPolicy - policy applied to version selection, e.g. whether to prefer downgrades, upgrades or request an exact version. The default is RequestVersionOrLower. Full path: ClusterConfig.HttpRequest.VersionPolicy. Type: HttpVersionPolicy?

Yarp.Telemetry.Consumption package

On .NET Core 3.1 it supports only:

  • YARP events and metrics
  • Kestrel events

On .NET 5 and higher it supports events and metrics for:

  • YARP
  • Kestrel
  • HTTP (SocketsHttpHandler)
  • NameResolution (DNS)
  • NetSecurity (SslStream)
  • Sockets

Building for .NET Core 3.1

YARP can be run on the .Net Core 3.1 runtime, but the .NET 5.0 SDK is still required for this runtime version because YARP APIs use C# 9 language features. Thus, the steps to create a YARP-based application are as follows:

  1. Install the .NET 5.0 SDK: https://dotnet.microsoft.com/download/dotnet/5.0
  2. Add the reference to the YARP package to the application project
  3. Add the property <LangVersion>9.0</LangVersion> to the .csproj file
  4. Add a new IsExternalInit.cs file with the following content to the root of the project.
namespace System.Runtime.CompilerServices
{
    // Allows "init" properties in .NET Core 3.1.
    internal static class IsExternalInit { }
}

These are related improvements in .NET 5.0 or ASP.NET Core 5.0 that YARP is able to take advantage of:

  • HTTP/3 - support for inbound and outbound connections (preview).
  • Distributed Tracing - .NET 6.0 has built-in configurable support that YARP takes advantage of to enable more scenarios out-of-the-box.
  • Http.sys Delegation - a kernel-level ASP.NET Core 6 feature that allows a request to be transferred to a different process.
  • UseHttpLogging - includes an additional middleware component that can be used to provide more details about the request and response.
  • Dynamic HTTP/2 window scaling - improves HTTP/2 download speed on high-latency connections.
  • NonValidated headers - improves perfomance by using non-validated HttpClient headers.