Configure for Build Engine on remote machine?

How can I have sfsdk use the Docker build engine of a remote machine?

You can’t. Well, I suppose it could be theoretically done by having a docker container ,running on the local host, forwarding the ssh port to the remote container. But we definitely do not support such a setup.

How is it sending commands to the engine? TCP only?

nmap on the host with the engine running gives me these ports as open:

22/tcp   open  ssh
2222/tcp open  EtherNetIP-1
7777/tcp open  cbt