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(); }