ASPNET Core MVC Program.cs to use appsettings json files and EnvironmentVariables configurations

Program.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

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

    public static IWebHostBuilder CreateWebHostBuilder (string[] args) {
      return WebHost.CreateDefaultBuilder (args)
        .ConfigureAppConfiguration (ConfigConfiguration)
        .UseStartup<Startup> ();
    }

    static void ConfigConfiguration (WebHostBuilderContext ctx, IConfigurationBuilder config) {
      config.SetBasePath (Directory.GetCurrentDirectory ())
        .AddJsonFile ("appsettings.json", optional : false, reloadOnChange : true)
        .AddJsonFile ($"appsettings.{ctx.HostingEnvironment.EnvironmentName}.json", optional : true, reloadOnChange : true)
        .AddEnvironmentVariables ();
    }
  }
}