ASP.NET Core middleware and features share the routing pipeline, therefore an app can be configured to serve additional request handlers. The additional request handlers, such as MVC controllers, work in parallel with the configured gRPC services.

Server options

gRPC services can be hosted by all built-in ASP.NET Core servers.

[!div class="checklist"]

Kestrel

TestServer

IIS†

HTTP.sys†

†Requires .NET 5 and Windows 11 Build 22000 or Windows Server 2022 Build 20348 or later.

For more information about choosing the right server for an ASP.NET Core app, see xref:fundamentals/servers/index.

Kestrel

Kestrel is a cross-platform web server for ASP.NET Core. Kestrel focuses on high performance and memory utilization, but it doesn't have some of the advanced features in HTTP.sys such as port sharing.

Kestrel gRPC endpoints:

Require HTTP/2.
Should be secured with Transport Layer Security (TLS).

HTTP/2

gRPC requires HTTP/2. gRPC for ASP.NET Core validates HttpRequest.Protocol is HTTP/2.

Kestrel supports HTTP/2 on most modern operating systems. Kestrel endpoints are configured to support HTTP/1.1 and HTTP/2 connections by default.

TLS

Kestrel endpoints used for gRPC should be secured with TLS. In development, an endpoint secured with TLS is automatically created at https://localhost:5001 when the ASP.NET Core development certificate is present. No configuration is required. An https prefix verifies the Kestrel endpoint is using TLS.

In production, TLS must be explicitly configured. In the following appsettings.json example, an HTTP/2 endpoint secured with TLS is provided:

[!code-json]

Alternatively, Kestrel endpoints can be configured in Program.cs:

[!code-csharp]

For more information on enabling TLS with Kestrel, see Kestrel HTTPS endpoint configuration.

Protocol negotiation

TLS is used for more than securing communication. The TLS Application-Layer Protocol Negotiation (ALPN) handshake is used to negotiate the connection protocol between the client and the server when an endpoint supports multiple protocols. This negotiation determines whether the connection uses HTTP/1.1 or HTTP/2.

If an HTTP/2 endpoint is configured without TLS, the endpoint's ListenOptions.Protocols must be set to HttpProtocols.Http2. An endpoint with multiple protocols, such as HttpProtocols.Http1AndHttp2 for example, can't be used without TLS because there's no negotiation. All connections to the unsecured endpoint default to HTTP/1.1, and gRPC calls fail.

For more information on enabling HTTP/2 and TLS with Kestrel, see Kestrel endpoint configuration.

[!NOTE] macOS doesn't support ASP.NET Core gRPC with TLS before .NET 8. Additional configuration is required to successfully run gRPC services on macOS when using .NET 7 or earlier. For more information, see Unable to start ASP.NET Core gRPC app on macOS.

IIS

Internet Information Services (IIS) is a flexible, secure and manageable Web Server for hosting web apps, including ASP.NET Core. .NET 5 and Windows 11 Build 22000 or Windows Server 2022 Build 20348 or later are required to host gRPC services with IIS.

IIS must be configured to use TLS and HTTP/2. For more information, see xref:host-and-deploy/iis/protocols.

HTTP.sys

HTTP.sys is a web server for ASP.NET Core that only runs on Windows. .NET 5 and Windows 11 Build 22000 or Windows Server 2022 Build 20348 or later are required to host gRPC services with HTTP.sys.

HTTP.sys must be configured to use TLS and HTTP/2. For more information, see HTTP.sys web server HTTP/2 support.

Host gRPC in non-ASP.NET Core projects

An ASP.NET Core gRPC server is typically created from the gRPC template. The project file created by the template uses Microsoft.NET.SDK.Web as the SDK:

[!code-xml]

The Microsoft.NET.SDK.Web SDK value automatically adds a reference to the ASP.NET Core framework. The reference allows the app to use ASP.NET Core types required to host a server.

You can add a gRPC server to non-ASP.NET Core projects with the following project file settings:

[!code-xml]

The preceding project file:

Doesn't use Microsoft.NET.SDK.Web as the SDK.
Adds a framework reference to Microsoft.AspNetCore.App.
- The framework reference allows non-ASP.NET Core apps, such as Windows Services, WPF apps, or WinForms apps to use ASP.NET Core APIs.
- The app can now use ASP.NET Core APIs to start an ASP.NET Core server.
Adds gRPC requirements:
- NuGet package reference to Grpc.AspNetCore.
- .proto file.

For more information about using the Microsoft.AspNetCore.App framework reference, see Use the ASP.NET Core shared framework.

Integration with ASP.NET Core APIs

gRPC services have full access to the ASP.NET Core features such as Dependency Injection (DI) and Logging. For example, the service implementation can resolve a logger service from the DI container via the constructor:

csharp

public class GreeterService : Greeter.GreeterBase
{
    public GreeterService(ILogger<GreeterService> logger)
    {
    }
}

By default, the gRPC service implementation can resolve other DI services with any lifetime (Singleton, Scoped, or Transient).

Resolve HttpContext in gRPC methods

The gRPC API provides access to some HTTP/2 message data, such as the method, host, header, and trailers. Access is through the ServerCallContext argument passed to each gRPC method:

[!code-csharp]

ServerCallContext doesn't provide full access to HttpContext in all ASP.NET APIs. The GetHttpContext extension method provides full access to the HttpContext representing the underlying HTTP/2 message in ASP.NET APIs:

[!code-csharp]

Additional resources

:::moniker-end