Prometheus is a powerful Open Source platform for collecting system metric data, querying this data, and specifying alerts for it. It's especially appropriate for multi-dimensional time series data, such as throughput, performance and availability. It automatically monitors standard NodeJS metrics, as well as enabling the creation of custom, app-specific metrics. Prometheus integrates with Grafana, an Open Source analytics and interactive visualization web application, for sophisticated yet straightforward data analysis. In this session I provide an overview of these services, and their internal operation. I explain how best integrate them into your environment, and get the most value from them. This is based on our extensive utilization of Prometheus and Grafana across our entire system.