Docker Swarm is a mode in which Docker deploys container services across a cluster. Spreading a service across multiple swarm nodes (systems running Docker joined to the same swarm cluster) allows us to perform load balancing and rolling updates to our application. We also can easily horizontally scale by adding more nodes and scaling services up. Previously when we’ve worked with Docker Compose files, we’ve declared services made up of containers and their operational parameters; we can deploy these same compose files as a “stack” in swarm mode. Our goal this month is to cover how to build container images for our application and orchestrate the services required to support our app in a testing or staging environment.