Painless Docker - 2nd Edition

Docker's Place in Container History

Docker is often misunderstood. Some see it purely as a container runtime/environment, while others describe it as a full platform. Both views are partially correct, depending on the layer being discussed.

When Docker was first released, it was built on top of LXC, using it as the underlying container runtime. Docker's initial goal was not to invent containerization, but to provide a simple API and workflow for creating, running, and managing isolated processes. It focused on defining containers as single-application units with a clear lifecycle, from build to execution and teardown.

In early 2013, the Docker project explicitly aimed to define a standard container format, as described in the original Docker manifesto. The idea was to create a portable, executable unit that could run consistently across environments.

At its core, Docker introduced a way to package and run software as self-contained units that include application code, runtime, system tools, and libraries. This packaging model, rather than the low-level isolation mechanism itself, was Docker's most important contribution.