What is the role of Docker Swarm?

The role of Docker Swarm is primarily to orchestrate a cluster of Docker hosts. This means that Docker Swarm manages a group of Docker engines or hosts to work together as a single virtual host. It allows for the efficient management of containerized applications across multiple machines, providing features such as load balancing, service discovery, scaling, and fault tolerance.

With Docker Swarm, users can deploy services across several containers that can spread out over different hosts, allowing for higher availability and resilience. It simplifies the deployment of applications in a distributed environment by overseeing the state and ensuring that the desired state of the application is maintained, even in the event of failures.

While the other choices mention important aspects of working with Docker, they do not encapsulate the primary function of coordinating clusters of Docker hosts, which is central to Docker Swarm's capabilities.