Understanding the project templates

The Visual Studio template for creating an ASP.NET Core project, since version 3.x, adds the following (or very similar) contents to the Program class:

publicstaticvoid Main(string[] args)
{
    CreateHostBuilder(args).Build().Run();
}
 
publicstatic IHostBuilder CreateHostBuilder(string[] args) =>
    Host
        .CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(builder =>
        {
            builder.UseStartup<Startup>();
        });

This has changed a bit since previous versions and is now more opinionated; I already showed this when talking about OWIN earlier in this chapter.

The Host class exposes the static CreateDefaultBuilder, which returns a fully built IHostBuilder instance. The CreateDefaultBuilder method is actually doing a lot of things behind our backs:

• Creates a ConfigurationBuilder and adds the environment variables provider to it (see Chapter 2, Configuration...