Docker for Rails Developers

Describing Our App to Swarm

You’re probably becoming pretty comfortable describing our app as a set of services defined in a Compose file. However, a docker-compose.yml file is development-focused; it lets us rebuild images easily and not get bogged down in unnecessary details such as deployment configuration. However, now when we come to deployment, we need something that is deployment-focused.

Swarm introduces the concept of a stack to mean an application made up of a group of services that are capable of being deployed. We describe our stack to Swarm with a deployment-focused variant of a Compose file known as a stack file. Although you’ll sometimes still hear this referred to as a Compose file, we’ll stick with the latter since it clearly ...