YARP Supported Runtimes

YARP 1.0 previews support ASP.NET Core 3.1 and 5.0. You can download the .NET 5 SDK from https://dotnet.microsoft.com/download/dotnet/5.0. See Releases for specific version support.

YARP is taking advantage of ASP.NET Core 5.0 features and optimizations. This does mean that some features may not be available if you're running on ASP.NET Core 3.1.

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: