Ahh!
I’ve never used docker.
so okybaca got no idea 
(me neither programmed yacy nor understand its code. i just use it for some years and try to document the black-box as i go, from what i observe, hoping it would help)
But if you somehow examine that, could you write a resume for the others?
afaik, there is a docker readme as well.
Is that you want to modify the network definition? Could the solution be building docker image by yourself?