need to be able to update gold on a running instance

[pahp]

Attacks often find true bugs in the gold program. We need to be able to update the gold program of a running instance. I propose that the admin should be able to push to a repo where gold lives and it is rebuilt and cached upon a change. Players always find bugs in gold.

[ChandlerSwift]

When we fix this, we'll have to make sure that we remove any cached Docker instance as well, or force a rebuild of it. Currently we cache the gold image, and that would cause problems if we ever wanted to update it during a competition.

[ChandlerSwift]

Removing the docker image after updating the code in /pack/gold is sufficient to trigger a rebuild. docker image rm gold (possibly after docker container prune to remove all containers that might depend on it) removes the gold image, and forces a rebuild.

In theory, it would be nice to be able to do this more automatically. @pahp, discussion on what this looks like?

[ChandlerSwift]

Also, it would not be terribly difficult to add a button to the admin UI to perform this docker image rm step, though it removes one layer of separation between the web UI and the docker control plane that is nice to have for security-in-depth, as it would require us to let the web container be able to control Docker.