Many developers enjoy using Compose to model their applications, for example applications similar to WordPress. We do the same and think that it's a fantastic way to describe and manage micro services on Docker. However, at the time of writing this book, no support for Docker Swarm Mode is available in Compose yet and all containers are scheduled on the current node. To deploy an application across the swarm, we need to use the new bundle feature of stacks.
At the time of writing, stacks are available only experimentally, but we're showing them here just to give you a taste of what it will be like to deploy microservices on Docker in the (near) future.