What is the Leader Election Pattern?

A pattern used in distributed systems to coordinate the actions of a collection of collaborating instances by electing one as the leader.

When multiple instances of a worker service are running, you don't want them all executing the same cron job or polling the same queue and duplicating work. Leader election algorithms (like Paxos, Raft, or using Redis/ZooKeeper locks) ensure only one instance assumes the role of the leader.