How to specify the port an ASP.NET Core application is hosted on?

Question

When using WebHostBuilder in a Main entry-point, how can I specify the port it binds to?

By default it uses 5000.

Note that this question is specific to the new ASP.NET Core API (currently in 1.0.0-RC2).

Answer 1

In ASP.NET Core 3.1, there are 4 main ways to specify a custom port:

• Using command line arguments, by starting your .NET application with --urls=[url]:

dotnet run --urls=http://localhost:5001/

• Using appsettings.json, by adding a Urls node:

{
  "Urls": "http://localhost:5001"
}

• Using environment variables, with ASPNETCORE_URLS=http://localhost:5001/.
• Using UseUrls(), if you prefer doing it programmatically:

public static class Program
{
    public static void Main(string[] args) =>
        CreateHostBuilder(args).Build().Run();

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(builder =>
            {
                builder.UseStartup<Startup>();
                builder.UseUrls("http://localhost:5001/");
            });
}

Or, if you're still using the web host builder instead of the generic host builder:

public class Program
{
    public static void Main(string[] args) =>
        new WebHostBuilder()
            .UseKestrel()
            .UseContentRoot(Directory.GetCurrentDirectory())
            .UseIISIntegration()
            .UseStartup<Startup>()
            .UseUrls("http://localhost:5001/")
            .Build()
            .Run();
}