What command is used to scale a service in Docker Swarm?

The command used to scale a service in Docker Swarm is indeed "docker service scale." This command allows you to specify the desired number of replicas for a service running in a Swarm mode. By adjusting the number of replicas, you can manage the load across your application, thereby ensuring that it remains responsive under various levels of demand.

For instance, if you need to increase the capacity of your application to handle more requests, you can simply execute "docker service scale [SERVICE_NAME]=[NEW_REPLICA_COUNT]." This command both creates new instances of your service as needed and ensures that they are properly distributed across the nodes in the Swarm.

Using this command effectively allows for dynamic scaling, which is essential for maintaining high availability and performance in a microservices architecture. Scaling services up or down as demand fluctuates is a critical feature for operational efficiency and resource management in container orchestration systems like Docker Swarm.