Hosting

Set up a host

Create a host using an instance of IWebHostBuilder. A typical app calls CreateDefaultBuilder to start setting up a host:

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

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

CreateDefaultBuilder performs the following tasks:

• Configures Kestrel server as the web server using the app's hosting configuration providers.

• Sets content root to the path returned by Directory.GetCurrentDirectory.

• Loads host configuration from:

  • Environment variables prefixed with ASPNETCORE_ (for example, ASPNETCORE_ENVIRONMENT).

  • Command-line arguments.

• Loads app configuration in the following order from:

  • appsettings.json.

  • appsettings.{Environment}.json.

  • Secret Manager when the app runs in the Development environment using the entry assembly.

  • Environment variables.

  • Command-line arguments.

• Configures logging for console and debug output.

• When running behind IIS, enables IIS Integration.

• Sets ServiceProviderOptions.ValidateScopes to true if the app's environment is Development.

When ValidateScopes is set to true, the default service provider performs checks to verify that:

• Scoped services aren't directly or indirectly resolved from the root service provider.

• Scoped services aren't directly or indirectly injected into singletons.