Docker for Rails Developers

Before We Begin

Got Docker installed? Great, you’re just in time—I didn’t want to start without you. Before we get our hands dirty and start playing with Docker, it’s helpful to understand two fundamental concepts: containers and images.

What Is a Container?

Conceptually, a container is an isolated or “sandboxed” execution environment—an empty vessel for executing software in. Containers rely on virtualization features built in to the Linux (and more recently, Windows^[13]) kernel, which let you create a fully isolated set of processes that don’t know (or care) about the rest of the system. In fact, inside a container, it appears to be a complete Linux (or Windows) system, even though, in reality, all its resources and capabilities come from the ...