Refactoring to Microservices - Introducing Docker Swarm

In my [previous blog] I used local images wired together with a docker-compose.yml file. This was an improvement over stand alone containers. Networking is now more robust because code in images uses names instead of IP addresses to access services. This time my goal is to introduce Swarm so I can distribute components over multiple hosts and run more instances if necessary. Next, I'll describe step one: migrate the docker-compose-single-host setup to a Docker Swarm multi-host version. [More].