I have an ARM based board that can only run a specific buildroot based distro provided by the manufacturer. I would like to try to run Docker on this board.
Any time I combine buildroot and docker in a Google search, I wind up getting pages that explain how to use buildroot to create a container, not how to alter buildroot to use it as the host.
Can anyone point me to some documentation?
The keyword you're missing is "engine".
It's the Docker Engine that allows the host OS to support Docker containers.
There's a submitted 3-part patch to add Docker Engine support to Buildroot.
[Buildroot] [PATCH v6 0/3] Add docker engine support
This series adds runc, docker-containerd, and docker-engine support.
Patch 1 adds runC, the new minimal CLI for running linux containers.
Patch 2 adds docker-containerd, the daemon and API for runC.
Patch 3 adds docker-engine, the cli and api for the Docker application
engine.