vzdump-vms pushes vzdump_last_{run,success}_timestamp + vzdump_last_status to
Pushgateway job vzdump-backup, but nothing alerted on them — a stopped/failing VM
backup would be silent (exactly how the nfs-mirror reaping went unnoticed until I
re-verified). Add the trio to the 3-2-1 group in prometheus_chart_values.tpl,
mirroring the LVM/pfSense/nfs-mirror alerts. Stale = >~50h since last success.
NOT [ci]-applied: this is a Terraform stack change — arms on the next
`scripts/tg apply` of the monitoring stack (metrics already flow, so it arms
immediately once applied). Admin-gated apply per org policy.
[ci skip]
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>