1e3386fac8
Deployed as a StatefulSet with three replicas, and MQTT has no queue groups — every subscriber receives every message. All three pods would commit the same bill and publish three acks. Nothing double-counts, because the ingest deduplicates on the till's UUID and holds an advisory lock, but it is three times the database work and three times the traffic for one sale. Ordinal 0 consumes; the others stay idle. A StatefulSet already guarantees stable unique ordinals, so this is a deterministic election with no lock, no lease and no new dependency. If that pod dies the set recreates it and tills hold their bills meanwhile, which is what they are built to do. POS_MQTT_CONSUMER=always/never overrides it for deployments that are not a StatefulSet. Anything without an ordinal name — a Deployment pod, a bare container, local development — consumes, because a lone instance that silently refused to would be a far more confusing failure than one that did. The client id now defaults to the pod name rather than a constant. Two connections sharing an id evict each other in a reconnect loop that looks exactly like a flapping network, and takes a while to recognise as anything else. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
14 KiB
14 KiB