Coordination service.
also: coordination services · ZooKeeper · Zookeeper · etcd · ConsulA small, strongly consistent store (ZooKeeper, etcd) built on consensus, used for leader election, locks, configuration and membership.
the two-minute refresher
- Don't build consensus yourself: etcd runs Raft, ZooKeeper runs Zab.
- ZooKeeper's ephemeral nodes vanish when a client's session dies: automatic release.
- Sequential nodes give fair ordering, and their numbers work as fencing tokens.
- etcd offers leases with TTLs and watches; Kubernetes controllers elect leaders with a Lease object.