public Startup(IHostingEnvironment env){}

public static void Main(string[] args)
{
        var builder = new ConfigurationBuilder()
            .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
            .AddJsonFile("hosting.json");
        builder.AddEnvironmentVariables();
        _configuration = builder.Build();
       ...
       var host = new WebHostBuilder()
            .UseKestrel(options =>
            {
                // options.ThreadCount = 4;
                options.NoDelay = true;
                options.UseHttps(testCertPath, _configuration["pfxPassword"]);
                options.UseConnectionLogging();
            })
}