On 2026-10-14 nine swarm services sat at 0/1 and nothing fired. From each
manager's swarm report the docker plugin now records three figures on
resource "swarm": swarm_services_short, swarm_nodes_down and
swarm_managers_unreachable. Drained nodes are left out of the last two,
since a drain is deliberate. The figures are recorded at most once every
30 s whichever manager reported, and are offered to alert rules.
Agent 1.19.0 sends each manager's ManagerStatus.Reachability. Older agents
fall back to the node's status.
A maintenance job on a swarm node also keeps a window over docker/swarm,
so its drain and reboot hold those alerts until the job ends.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
