Docker Containerization Docker Swarm and Orchestration 2

Question 1

What command promotes an existing Swarm worker node to a manager?

Accepted Answer

docker node promote <node>

Answer

The 'docker node promote <node>' command changes a worker node's role to manager in a Docker Swarm cluster.

Question 2

Which Swarm placement constraint would restrict a service to only run on nodes labeled 'env=production'?

Accepted Answer

--constraint 'node.labels.env==production'

Answer

Placement constraints use the syntax --constraint 'node.labels.==' to target nodes with specific labels.

Question 3

What happens to tasks on a Swarm node when it is set to 'drain' availability?

Accepted Answer

Running tasks are rescheduled on other nodes

Answer

Setting a node to drain availability stops new tasks from being assigned and reschedules existing tasks to other available nodes.

Question 4

In Docker Swarm, what is a 'task' in the context of a service?

Accepted Answer

A single running instance of a service container

Answer

A task is the atomic unit of scheduling in Swarm, representing one running container instance of a service replica.

Question 5

Which command updates a running Swarm service to use a new image version?

Accepted Answer

docker service update --image :

Answer

The 'docker service update --image' command performs a rolling update of the service to use the specified image version.

Docker Practice Test