Terminology

Docker engine is the software providing the libraries, services and toolsets of Docker. It enables computer to build Docker images and lauch Docker containers. Docker engine has two different editions: the community edition (Docker CE) and the enterprise edition (Docker EE).

Docker node/host is a physical or virtual computer on which the Docker engine is enabled.

Docker swarm cluster is a group of connected Docker nodes. Each node has either a manager or worker role in the cluster. At least one master node is required for a docker swarm cluster to function.

Manager refers to the node maintaining the state of a docker swarm cluster. There can be one or more managers in a cluster. The more managers in the cluster, the higher level of the cluster fault-tolerance. The level of fault-tolerance is explained in this document.

Worker refers to the node sharing the container workload in a docker swarm cluster.

Docker image is an executable package that includes everything needed to run an application–the code, a runtime, libraries, environment variables, and configuration files.

Docker container is a runtime instance of an image. A container is launched by running an Docker image.

Docker service is a logical representation of multiple replicas of the same container. Replicas are used for service load-balancing and/or failover.

Docker stack is a set of linked Docker services.