Program.cs

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

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

        public static IWebHost BuildWebHost(string[] args)
        {
            return new WebHostBuilder()
                .UseKestrel()
                .UseContentRoot(Directory.GetCurrentDirectory())
                .ConfigureAppConfiguration((hostingContext, config) =>
                {
                    var env = hostingContext.HostingEnvironment;
                    config.AddJsonFile("appsettings.json", false, false)
                        .AddJsonFile($"appsettings.{env.EnvironmentName}.json", false, false)
                        .AddEnvironmentVariables();
                })
                .UseStartup<Startup>()
                .Build();
        }
    }
}