Sometimes more flexibility is needed across projects than simply to differentiate Python package versions. For example, it might be necessary to support an application on an existing version of Python itself, or perhaps MySQL, while simultaneously developing an update that relies upon a newer version of the software. Docker is capable of that level of isolation.

Docker is a system for creating configured, customized virtual machines called containers. It allows duplicating the setup of any production server precisely. In some cases, it is even possible to deploy pre-built containers directly to remote servers as well.