# 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