Raft-backed config store (etcd-style)
A five-node Raft consistent core serving linearizable configuration with leases and watch notifications — the etcd/Consul architecture under Kubernetes.
What this design does
The pattern at the bottom of Kubernetes, Consul and every service registry that can't afford to lie: a small Raft cluster (the consistent core) owns the truth, clients write through the leader, and watchers get pushed changes instead of polling. Leases keep ephemeral entries honest when their owners die. Our blog post 'Raft, explained with one diagram' walks the consensus mechanics in depth.
The patterns it composes
- Raft consensus — one leader per term; entries commit on majority ack (3 of 5)
- Consistent core — a small strongly-consistent kernel coordinates a large fluffy system
- Lease — ephemeral keys expire unless their owner heartbeats — liveness without cleanup jobs
- State watch — clients subscribe to key changes; the store pushes instead of being polled
- Quorum sizing — 5 nodes tolerate 2 failures; writes stall below majority — by design
Import it, attach your own numbers, and verify the design against failures — or read the engineering notes.