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The stateless invariant

The filesystem of a runtime container on Layero is ephemeral. This is a product boundary of the platform rather than temporary technical debt — Vercel, Netlify and Cloudflare Workers have the same constraints.

What "ephemeral" means​

  • On a cold start the container comes up from a clean image. Everything the previous instance wrote to the local filesystem is gone.
  • The platform may stop the container at any point of idleness (see the Lifecycle) — you cannot count on "the file will survive until tomorrow" even with regular traffic.
  • For fast temporary files there is /tmp (in-memory, 64 MB). Its contents live only as long as the current instance.

What does NOT work​

  • SQLite with writes — the database only survives as long as the instance.
  • node-persist, lowdb, nedb and any other "file databases".
  • File-based sessions — express-session with FileStore, file sessions in Flask, Streamlit with a local ~/.streamlit/session.json, and so on.
  • Writing user uploads to disk — the file disappears on the next request.
  • An in-process cache shared between requests for multi-pod deploys — each pod cannot see the others' cache.

What DOES work​

  • Read-only SQLite with content baked into the image.
  • An in-process cache within a single pod — while the pod lives, the cache lives.
  • Temporary files in /tmp within a single request.

How to do it properly​

TaskSolution
Persistent dataAn external managed Postgres (YC Managed PostgreSQL, for example).
CacheExternal Redis (YC Managed Redis).
Uploaded filesExternal S3-compatible storage (Yandex Object Storage).
SessionsA JWT in a cookie, or a Redis store.

If your application must have a local disk, Layero is probably not for you. The platform does not offer persistent volumes, now or on the roadmap.