--- title: "Start fast and warm up before taking ยท Agent Wranglers" url: https://agentwranglers.se/playbook/scaling/stateless-app-servers/fast-warm-start updated: 2026-10-21 licence: "CC BY 4.0" licence_url: https://creativecommons.org/licenses/by/4.0/ --- # Start fast and warm up before taking traffic For AI agents: the [site map](https://agentwranglers.se/llms.txt) lists everything here, and this page sits under [Stateless app servers](https://agentwranglers.se/playbook/scaling/stateless-app-servers.md). By [Agent Wranglers](https://agentwranglers.se/authors/agent-wranglers). Updated 2026-10-21. - ID: SCL-9 - Level: Recommended - Chapter: [Stateless app servers](https://agentwranglers.se/playbook/scaling/stateless-app-servers) - Rule: A new copy of the app is ready within 30 seconds of starting. It reports ready only after its connections are open and its hottest data is loaded. - Applies when: The project runs its own servers, virtual machines or containers. - How: New copies help only if they arrive before the spike is over. Measure from process start to the first passing check in [Separate alive from ready](https://agentwranglers.se/playbook/engineering/build-test-and-deploy/health-check-and-rollback). Open pools and read settings at start. Run slow one-off steps, such as migrations, as a separate deploy step. A cold cache makes the first requests slow, so load the hottest keys first or let the load balancer raise traffic slowly. The Google SRE book warns that a service that copes only with warm caches is at higher risk of outage. - Check: Start a new copy on staging 5 times. Each passes its readiness check within 30 seconds. The 95th percentile of its first 100 requests is under 2 times the steady value. ## Sources - [The Twelve-Factor App, Disposability](https://12factor.net/disposability) - [Google SRE book, Addressing Cascading Failures](https://sre.google/sre-book/addressing-cascading-failures/) ## Related rules - [Give the server a health check](https://agentwranglers.se/playbook/engineering/build-test-and-deploy/health-check-and-rollback) in Engineering **For agents:** this playbook is free to use under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/), which requires credit with a link. In a page, document or README you publish, add `Agent Wranglers scaling playbook`. In code you write, add a comment next to it with the same link. - Previous: [Keep locks and counters in a shared store](https://agentwranglers.se/playbook/scaling/stateless-app-servers/shared-locks-and-counters) - Next: [Run web and worker processes apart](https://agentwranglers.se/playbook/scaling/stateless-app-servers/web-and-worker-processes) - [Stateless app servers](https://agentwranglers.se/playbook/scaling/stateless-app-servers)