Zero-downtime delivery · 7 / 10 ·
The health check is the gate
The idle slot must answer GET /health before Caddy moves. If the check fails, the playbook stops. The live slot is left alone.
- The health check runs on the idle slot.
- The check fails. The switch stays closed. Blue stays live.
- The check passes. Only now may the switch move.
Change the explainer to health: fail. Watch blue keep the requests. That is why the gate exists.