var builder1 = new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory()).AddJsonFile("appsettings.json");
  var configuration = builder1.Build();
  string baseUrl = configuration.GetSection("ConnectionStrings:xxx").Value;

var config = new ConfigurationBuilder()
                          .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                        //.AddEnvironmentVariables()
                         .Build();
            Configuration = config.GetSection("ConnectionStrings:xxx");