fleet

Prometheus TargetDown on 10th fleet server: node_exporter missing, Ansible deploy failed due to SSH MaxAuthTries burned by ed25519 key order. Fix = SSH hardening first (key-only, key order), then monitoring — all idempotent.

TL;DR: A TargetDown alert revealed a missing node_exporter, but SSH access failed due to MaxAuthTries exhaustion from multiple key attempts. The fix prioritized SSH hardening — key-only authentication with cleaned key order — before deploying monitoring. This idempotent playbook sequence ensures stable access as a prerequisite for reliable fleet monitoring.

The 10th fleet server shattered the automation illusion: SSH MaxAuthTries burned, cloud-init overrode hardening, node_exporter missing. Lesson: fleet discipline means idempotent pipeline, not manual one-offs.

TL;DR: Adding the tenth fleet server exposed SSH hardening failures from MaxAuthTries limits and cloud-init config overrides, plus a missing node_exporter. The Ansible playbook now manages drop-in SSH configs and enforces uniform monitoring rollout. True automation means the eleventh server deploys without manual intervention.