Swarm Manager High Availability (HA)
Explore the concept of high availability in Docker Swarm manager nodes. Understand how leader and follower managers work together using Raft to maintain cluster consistency. Learn best practices like deploying an odd number of managers, quorum importance, and network considerations to keep Swarm clusters operational without service interruptions.
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Swarm managers
Swarm clusters are highly available (HA), meaning one or more managers can fail and the swarm will keep running.
Technically speaking, Swarm implements active/passive multi-manager HA. This means a swarm with three managers will have one active manager and the other two will be passive. In a swarm, we call the active manager the leader and the passive managers the followers, and the leader is the only manager who can update the swarm configuration. If the leader fails, one of the followers will be elected as the new leader, and the swarm will keep running without any service interruption. If you send commands to a follower, it proxies them to the leader. ...