"swarm services short on swarm is 6." becomes "6 swarm services are
short of their replicas.", with a Which line naming each service and how
many of its tasks run. The swarm figures get labels, and the counting
figures (swarm, mounts, drives, updates) read as sentences in the email,
its subject and the Alerts page. A plugin names what its count counts
through core.alerts.names_behind; the Docker plugin does for the three
swarm figures, from the stored swarm. Webhooks get alert.which too.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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>