cluster verifiedcriticalWritten by the Hub
The cluster exchange
The fanout exchange over which nodes announce themselves and control messages travel.
In detail
Cluster membership is this exchange plus the shared database, and nothing else. Every node binds a private queue to it, so a message published here reaches all of them at once. Two messages matter. {"reload": true} makes every node re-read the settings database — the fast half of settings propagation, and the thing any external writer must send. {"hello": true} asks nodes to announce themselves immediately. Anything that can talk to the broker can publish them; no MailerQ API is involved. For Hub that is convenient and worth stating plainly: the credentials that let Hub read telemetry also let it reconfigure every node in the cluster.
What happens if you get it wrong
Nodes pointed at different cluster addresses or exchanges.They stop hearing each other. A reload reaches part of the fleet, and the rest keeps the old settings for up to database-ttl with nothing to show the split.inference · inference