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

        /// <summary>
        /// Build the web host and add the configurations
        /// </summary>
        /// <param name="args"></param>
        /// <returns></returns>
        public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .ConfigureAppConfiguration((builderContext, config) =>
                {
                    IHostingEnvironment env = builderContext.HostingEnvironment;

                    config
                        .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                        .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true)
                        .AddEnvironmentVariables();
                })
                .UseStartup<Startup>()
                .Build();
    }
}