Then came the staging environment. Staging mirrored production—three server nodes, two agents, a PostgreSQL database for Rancher, and a dozen critical microservices.
He pulled the backup—the one he’d taken before the upgrade, the one the runbook said to take but nobody ever does. He restored the /var/lib/rancher/k3s/server/db/ directory from a snapshot taken at 2:00 AM.
The upgrade script ran smoothly. curl -sfL https://get.k3s.io | sh -s - --channel=latest . The single-node development cluster in the ‘sandbox’ environment restarted in 47 seconds. Alex smiled, typed kubectl get nodes , and saw Ready . k3s downgrade version
Alex just responded: “Downgrade.”
Alex typed into the Slack channel: “Cluster recovered. Root cause: version skew during upgrade. Pinning all clusters to v1.27.4 until we test the etcd migration path.” Then came the staging environment
But every once in a while, at 2:47 AM, Alex would glance at the backup logs and whisper a small thanks to the night the downgrade worked.
The cluster was split-brained.
The reply came instantly: “How?”