only once

docker network create --subnet=172.172.0.0/16 silicone docker build -t silicone:base .

for each service to test

create a container with static ip

docker run --name etherpad -d --net silicone --ip 172.172.0.2 -it silicone:base

copy your ssh key

docker cp ~/.ssh/id_rsa.pub etherpad:/root/.ssh/authorized_keys docker exec -it etherpad chown root.root /root/.ssh/authorized_keys

then you can go with ansible using 172.172.0.2 as your host inside

inventory