https://medium.com/netflix-techblog/lessons-from-building-observability-tools-at-netflix-7cfafed6ab17

Our mission at Netflix is to deliver joy to our members by providing high-quality content, presented with a delightful experience. We are constantly innovating on our product at a rapid pace in pursuit of this mission. Our innovations span personalized title recommendations, infrastructure, and application features like downloading and customer profiles. Our growing global member base of 125 million members can choose to enjoy our service on over a thousand types of devices. If you also consider the scale and variety of content, maintaining the quality of experience for all our members is an interesting challenge. We tackle that challenge by developing observability tools and infrastructure to measure customers’ experiences and analyze those measurements to derive meaningful insights and higher-level conclusions from raw data. By observability, we mean analysis of logs, traces, and metrics. In this post, we share the following lessons we have learned:

We started our tooling efforts with providing visibility into device and server logs, so that our users can go to one tool instead of having to use separate data-specific tools or logging into servers. Providing visibility into logs is valuable because log messages include important contextual information, especially when errors occur.