public void Main(string[] args) { var builder = new ConfigurationBuilder("."); builder.AddJsonFile("appsettings.json"); builder.AddEnvironmentVariables(); var config = builder.Build(); builder.AddEntityFramework(options => options.UseSqlServer(config["Data:DefaultConnection:ConnectionString"])); config = builder.Build(); Console.WriteLine("key1={0}", config.Get("key1")); Console.WriteLine("key2={0}", config.Get("key2")); Console.WriteLine("key3={0}", config.Get("key3")); }