Docker in User Mode Linux
An image for running a dockerd inside a user mode linux kernel.
This way it is possible to run and build docker images without forwarding the docker socket or using privileged flags.
Therefore this image can be used to build docker images with the gitlab-ci-multi-runner docker executor.
How it works
It starts a user mode linux kernel with a dockerd inside.
The network communication is bridged by slirp.
I didn't managed to get the "redir" of slirp to work and so i'm forwarding the docker socket using TCP reverse tunneling over an SSH connection from the uml kernel to the container.