Hi, very-veRY-VERY great article!
Császi József

Glad you liked the article and helps you.

for updating the containers, the docker swarm services has a flag and a feature for handling updated i suggest you to give it a read for update docker services in swarm, and for communication between services i used http protocol, but there is a better approach by using tcp protocol communication, i would update the series by implementing tcp communication, i hope i can do it soon.