Can I set listen URLs in appsettings.json in ASP.net Core 2.0 Preview?

Question

I'm creating an ASP.net Core 2.0 app to run on the .net Core 2.0 runtime, both currently in their Preview versions. However, I cannot figure out how to have Kestrel use something other than the default http://localhost:5000 listen URL.

Most documentation that I could Google talks about a server.urls setting, which seems to have been changed even in 1.0-preview to just be urls, however neither works (turning on Debug logging has Kestrel telling me that no listen endpoints are configured).

A lot of documentation also talks about a hosting.json and that I can't use the default appsettings.json. However, if I compare the recommended approach of loading a new config, this looks pretty much exactly like what the new WebHost.CreateDefaultBuilder method does, except that it loads appsettings.json.

I currently don't understand how appsettings.json and IConfigureOptions<T> are related, if at all, so it's possible that my trouble stems from a lack of understanding of what KestrelServerOptionsSetup actually does.

Cacique

I found that appsettings.json can be used to set urls, see here: #46696615 – Exhibitor

Answer 1

I got it working with this

public static IWebHost BuildWebHost(string[] args) => 
        WebHost.CreateDefaultBuilder(args)
            .UseConfiguration(new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("hosting.json", optional: true)
                .Build()
            )
            .UseStartup<Startup>()
            .Build();

And the hosting.json

{ "urls": "http://*:5005;" }

Kickoff

Thank you. I misunderstood that CreateDefaultBuilder uses ConfigureAppConfiguration to load appsettings.json, which is different from UseConfiguration. – Cacique

I'm using .NET 5 and when I create a new MVC app there isn't a hosting.json file. Should I create it or is this an outdated way of settings the URLs? – Aqaba

Answer 2

To set listen URLs in appsettings.json, add "Kestrel" section:

"Kestrel": {
    "EndPoints": {
        "Http": {
            "Url": "http://localhost:5000"
        }
    }
}

Reference: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/servers/kestrel?view=aspnetcore-2.2

Eudosia

Does it affect deployment on a server instance? How is the priority or order if I also set an ASPNETCORE_URLS in my service config? – Hermann

Looks like ASPNETCORE_URLS (environment variable) has higher precedence than appsettings.json - See devblogs.microsoft.com/premier-developer/… – Eudosia

Worked for me too. Thank you. I wanted Kestrel to use a dynamic port and then I wanted to programmatically get that port. "Url": "http://*:0" did it. – Monopoly

Answer 3

Works for me as it used to be

WebHost.CreateDefaultBuilder(args)
    .UseConfiguration( new ConfigurationBuilder().AddCommandLine(args).Build() )
    .UseStartup<Startup>()
    .Build();

Then

dotnet myapp.dll --urls "http://*:5060;"

Thole

Answer 4

None of the above worked for me. This one worked for me:

public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
            .UseKestrel(options =>
            {
                options.Listen(System.Net.IPAddress.Loopback, 44306, listenOptions =>
                {
                    listenOptions.UseHttps("mysertificate.pfx", "thecertificatePassword");
                });
            })
        .Build();

(Change the 44306 to a port of your own liking)

And there might be a lot of help in this StackOverflow answer

Repudiate

Answer 5

None of these solutions really worked for me here in March 2024 running net8.0 and a minimal WebAPI with top-level statements.

I finally discovered code that I could add to my Program.cs that worked great:

var portNumber = 5270;
builder.WebHost.ConfigureKestrel((context, serverOptions) =>
{
    serverOptions.Listen(System.Net.IPAddress.Loopback, portNumber);
});

This set my app running on 127.0.0.1:5270.

Fantasm