如何从Main中获取IConfiguration？

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

public class Program
{
    public static void Main(string[] args)
    {
        var host = new HostBuilder()
            .ConfigureAppConfiguration((hostContext, config) =>
            {
                config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);
                config.AddEnvironmentVariables();
            })
            .ConfigureServices((hostContext, services) =>
            {
                services.AddSingleton<IConfiguration>(hostContext.Configuration);
                // 注册其他服务...
            })
            .Build();

        var configuration = host.Services.GetRequiredService<IConfiguration>();
        // 使用configuration获取配置值或绑定到自定义配置类中

        // 启动应用程序...
    }
}