The Service concept allows you to inspect the health and state of your cluster and the running applications.
You can view the list of all the tasks associated with a service across the cluster. In this case, each task is a container,
docker service ps http
You can view the details and configuration of a service via
docker service inspect --pretty http
On each node, you can ask what tasks it is currently running. Self refers to the manager node Leader:
docker node ps self
Using the ID of a node you can query individual hosts
docker node ps $(docker node ls -q | head -n1)
In the next step, we will scale the service to run more instances of the container.