public async Task Invoke(HttpContext httpContext)
        {
            if (httpContext.Request.Path.HasValue && httpContext.Request.Path.Value == "/metrics")
            {
                _logger.LogTrace($"{DateTime.Now:o} - Start scraping");

                var status = 1;
                try
                {
                    //todo: validate settings

                    Stopwatch sw = new Stopwatch();
                    sw.Start();

                    var gaugeModels = new List <GaugeModel>();

                    if (_serviceBusNamespace == null)
                    {
                        var azureCredentials  = SdkContext.AzureCredentialsFactory.FromServicePrincipal(_config.Value.ClientId, _config.Value.ClientSecret, _config.Value.TenantId, AzureEnvironment.AzureGlobalCloud);
                        var serviceBusManager = ServiceBusManager.Authenticate(azureCredentials, _config.Value.SubscriptionId);
                        _serviceBusNamespace = serviceBusManager.Namespaces.GetByResourceGroup(_config.Value.ResourceGroupName, _config.Value.ResourceName);
                    }

                    gaugeModels.AddRange(_queueService.CreateMetricsAsync(_serviceBusNamespace).GetAwaiter().GetResult());
                    gaugeModels.AddRange(_topicService.CreateMetricsAsync(_serviceBusNamespace).GetAwaiter().GetResult());
                    gaugeModels.AddRange(_subscriptionService.CreateMetricsAsync(_serviceBusNamespace).GetAwaiter().GetResult());

                    gaugeModels.Add(new GaugeModel()
                    {
                        Name  = "scrape_duration_milliseconds",
                        Value = (sw.ElapsedMilliseconds),
                        Help  = "The duration of the scrape in seconds",
                    });

                    foreach (var gaugeModel in gaugeModels)
                    {
                        var gauge = Metrics.CreateGauge(gaugeModel.Name, gaugeModel.Help, new GaugeConfiguration()
                        {
                            LabelNames = gaugeModel.Labels
                        });

                        gauge.WithLabels(gaugeModel.LabelValues).Set(gaugeModel.Value);
                    }
                }
                catch (Exception e)
                {
                    status = 0;
                    _logger.LogError($"{DateTime.Now:o} - {e.Message}");
                }
                finally
                {
                    var gauge = Metrics.CreateGauge("azureservicebusexporter_up",
                                                    "The status if the scrape was successful", new GaugeConfiguration());
                    gauge.Set(status);

                    _logger.LogTrace($"{DateTime.Now:o} - End scraping");
                }
            }

            await _next.Invoke(httpContext);
        }