non web.config config

Program.cs

using System;

namespace ConsoleApplication1
{
    public static class SosConfig
    {
        public static string CatalogApiUrl
        {
            get
            {
                var envValue = Environment.GetEnvironmentVariable("SosConfig.CatalogApiUrl");
                return string.IsNullOrEmpty(envValue) ? "https://dev.jockey.com/api/catalog" : envValue;
            }
        }

        //a bunch of more properties...
    }
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(SosConfig.CatalogApiUrl);

            Environment.SetEnvironmentVariable("SosConfig.CatalogApiUrl", "https://en.sosjdc.briefsqa.com/api/catalog");

            Console.WriteLine(SosConfig.CatalogApiUrl);
        }
    }
}