Program.cs

using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System;
using System.IO;

namespace IdentityServer
{
    public class Program
    {
        public static IConfiguration Configuration;

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

        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
            .ConfigureAppConfiguration((hostingContext, config) =>
            {
                config.Sources.Clear();
                config.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);
                config.AddEnvironmentVariables();
                if (args != null)
                {
                    config.AddCommandLine(args);
                }
            })
            .ConfigureLogging(logging =>
            {
                logging.ClearProviders();
                logging.SetMinimumLevel(LogLevel.Debug);
            })
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
    }
}