Issue with .ConfigureKestrel() method in .net Core

Question

I'm trying to create a very simple API with .net Core, and am exploring Kestrel. I am following the directions on this MS tutorial: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/servers/kestrel?view=aspnetcore-2.2

However, when I try to call the ConfigureKestrel method, Visual Studio tells me that "IWebHostBuilder does not contain a definition for 'ConfigureKestrel()' and no accessible extension method for ConfigureKestrel accepting a first argument of the type 'IWebHostBuilder' could be found (are you missing a using directive or an assembly reference?)"

I can't find any info on this, and I'm fairly sure I'm using the right libraries. Any help would be greatly appreciated - code is included:

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

namespace WebApplication2
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateWebHostBuilder(args).Build().Run();

        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
        .UseStartup<Startup>()
        .ConfigureKestrel((context, options) =>
        {
            // Error with ConfigureKestrel method above
        });
    }
}

Contribution

This is pretty sure an extension method from a namespace you do not import. – Dogberry

It's probably Microsoft.AspNetCore.Hosting or Microsoft.AspNetCore.Server.Kestrel – Ideally

Even while using both of those namespaces it still doesn't seem to resolve the error. – Contribution

Answer 1

I have created a sample application from scratch and this compiles:

using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;

namespace WebApplication1
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .ConfigureKestrel((a, b) => { });
    }
}

Can you check if this example works for you?

Please also check that you have the latest version of .Net Core, perhaps it was changed? The documentation is 2.2

Ideally

My issue is that I was running 2.1 - thanks for the answer! – Contribution

Answer 2

Found the VS2017 ASP.NET Core Web Application -> API running 2.1 does not have the ConfigureKestrel. However you can pass a KestrelServerOptions Action into UseKestrel instead which may give you the control your after. It overrides the settings from CreateDefaultBuilder.

    public static void Main(string[] args)
    {
        CreateWebHostBuilder(args).Build().Run();
    }

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>().UseKestrel(options => options.Listen(IPAddress.Loopback,60000));

Incidentally I just found if you start with a plain .NetCore console app, then add...

    Microsoft.AspNetCore
    Microsoft.AspNetCore.Mvc

This gives you a (fairly minimalist) project running AspNetCore 2.2 instead of 2.1

Shawnshawna

I'm kind of curious now... if you used the KestrelServerOptions Action with 2.2 would it win or would the values in the ConfigureKestrel Method win? – Shawnshawna