public ActionResult Hostname(string id)
        {
            var settings = new AppSettingsAuthConfig();
            var client = ArmHelper.GetWebSiteManagementClient(settings);

            var site = client.Sites.GetSite(settings.ResourceGroupName, settings.WebAppName);
            var model = new HostnameModel();
            model.HostNames = site.HostNames;
            model.HostNameSslStates = site.HostNameSslStates;
            model.Certificates = client.Certificates.GetCertificates(settings.ResourceGroupName).Value;
            model.InstalledCertificateThumbprint = id;
            if (model.HostNames.Count == 1)
            {
                model.ErrorMessage = "No custom host names registered. At least one custom domain name must be registed for the web site to request a letsencrypt certificate.";
            }

            return View(model);
        }
        private void SetViewBagHostnames()
        {
            var settings = new AppSettingsAuthConfig();
            var client = ArmHelper.GetWebSiteManagementClient(settings);

            var site = client.Sites.GetSite(settings.ResourceGroupName, settings.WebAppName);
            var model = new HostnameModel();
            ViewBag.HostNames = site.HostNames.Where(s => !s.EndsWith("azurewebsites.net")).Select(s => new SelectListItem()
            {
                Text = s,
                Value = s
            });
        }