Is it feasible to control Docker from inside a container?

Question

I have experimented with packaging my site-deployment script in a Docker container. The idea is that my services will all be inside containers and then using the special management container to manage the other containers.

The idea is that my host machine should be as dumb as absolutely possible (currently I use CoreOS with the only state being a systemd config starting my management container).

The management container be used as a push target for creating new containers based on the source code I send to it (using SSH, I think, at least that is what I use now). The script also manages persistent data (database files, logs and so on) in a separate container and manages back-ups for it, so that I can tear down and rebuild everything without ever touching any data. To accomplish this I forward the Docker Unix socket using the -v option when starting the management container.

Is this a good or a bad idea? Can I run into problems by doing this? I did not read anywhere that it is discouraged, but I also did not find a lot of examples of others doing this.

Answer 1

This is totally OK, and you're not the only one to do it :-)

Another example of use is to use the management container to hande authentication for the Docker REST API. It would accept connections on an EXPOSE'd TCP port, itself published with -p, and proxy requests to the UNIX socket.