Logging is usually the most boring part of learning a new technology, but not so with Docker. The basic principle is simple: you need to make sure your application logs are being written to the standard output stream, because that’s where Docker looks for them. There are a couple of ways to achieve that, which we’ll cover in this chapter, and then the fun begins. Docker has a pluggable logging framework--you need to make sure your application logs are coming out from the container, and then Docker can send them to different places. That lets you build a powerful logging model, where the application logs from all your containers are sent to a central log store with a searchable UI on top of it--all using open source components, all running in containers.