p8952/bocker

Bocker is a teaching and demonstration project that shows how the core ideas behind Docker can be expressed in about 100 lines of the shell scripting language bash. Docker is the popular tool many developers use to run software inside isolated containers. Bocker recreates a simplified version of that behavior to show what is happening under the hood. The project supports several of the same commands Docker users would recognize: pulling an image from a registry, listing images, running a container, viewing running containers, reading logs, committing changes back to an image, and removing containers or images. Networking is included, and there is basic support for CPU and memory limits via Linux control groups, a kernel feature that restricts how many resources a process can use. Port forwarding, data volumes, and a few other Docker features are not yet implemented. Because Bocker needs direct access to low-level Linux features, it has a list of system requirements that most standard computers will not meet out of the box. It needs a specific filesystem type (btrfs) mounted at a particular path, a manually configured network bridge, IP forwarding turned on, and firewall rules set up. The README also notes it must run as the system administrator (root) and could disrupt your network or system settings. For that reason, the project ships with a Vagrantfile, which lets you quickly spin up a separate virtual machine where Bocker can run safely without affecting your main system. Bocker is primarily a learning artifact rather than something intended for production use. It shows the concepts behind container isolation, image layering, and resource control in a compact, readable form. Anyone curious about what Docker actually does underneath its interface can read this code to get a concrete sense of the moving parts.