Migrate Vercel app: FastAPI

Summary

Move FastAPI compute from Vercel app to Ample, one component at a time. Destination verified on Ample: the app built, started and answered on its public HTTPS URL with encrypted configuration delivered. Source procedure: Copy environment variables from the Vercel project settings (or vercel env pull) into an env file you keep out of the repository. Not migrated automatically: Edge middleware, ISR revalidation, image optimization, cron jobs and Vercel integrations are not migrated and are unverified on Ample. Cutover: Add the custom domain with ample domain add, set the documented DNS records, keep the Vercel deployment until traffic is verified, then remove the domain from Vercel. Rollback: keep the source untouched until you confirm; nothing at the source is changed or deleted by this guide.

Infrastructure requirements

• Compute: verified (Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.)
• Postgres: verified (Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.)

Prerequisites

• Authorized access to the Vercel app source and its export tooling
• An inventory of every component in scope and out of scope
• A validated backup or copy before any cutover
• An Ample account token with servers:write, databases:read

Exact tested configuration

• template: python-3.12
• runtime: python
• size: s-1vcpu-1gb
• install: python3 -m pip install --target .ample/python -r requirements.txt
• start: PYTHONPATH=.ample/python:${PYTHONPATH:-} python3 run.py

Steps

1. Inventory the source. List what Vercel app provides beyond the component you are moving. Out of scope here: Edge middleware, ISR revalidation, image optimization, cron jobs and Vercel integrations are not migrated and are unverified on Ample.
2. Source step 1. Copy environment variables from the Vercel project settings (or vercel env pull) into an env file you keep out of the repository
3. Source step 2. Note the framework preset, build command and output directory; Ample detects the same from the repository
4. Source step 3. List Vercel-only features in use: edge middleware, ISR revalidation, image optimization, cron jobs, integrations
5. Deploy on Ample in parallel. pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template. Pass the exported variables with --env; keep the source running.

   ample deploy . --name <app-name> --public --start "python3 run.py" --env-file .env.production

6. Validate before cutover. Run the app's own checks and, for data, compare counts and checksums; the example checks are the pattern self-tests (/p/configuration-secrets, /p/relational-records).
7. Cut over. Add the custom domain with ample domain add, set the documented DNS records, keep the Vercel deployment until traffic is verified, then remove the domain from Vercel.
8. Rollback. Point DNS or configuration back to the source. The source was never modified; deletion is a separate, user-executed step after validation.

Tested examples

• FastAPI pattern fixture (destination) (tests/deploy-canaries/fastapi-patterns): Verified destination basis: FastAPI compute.

Success checks

• destination app responds on its public URL (/ on the live URL, expect ample canary fastapi patterns)
• configuration-secrets check from the destination example (/p/configuration-secrets on the live URL, expect see the pattern fixture checks)
• relational-records check from the destination example (/p/relational-records on the live URL, expect see the pattern fixture checks)
• data or object counts and checksums match the source

Limitations

• Documentation only: nothing is executed automatically and no execution binding is offered.
• The source-side procedure is documented from Vercel app's standard tooling and was not executed in this catalog's evidence; the destination side was verified with the pattern fixture.
• No full source-product parity is claimed: Edge middleware, ISR revalidation, image optimization, cron jobs and Vercel integrations are not migrated and are unverified on Ample.
• Verified on the python-3.12 template at s-1vcpu-1gb; region, compliance and request-duration limits are unknown.
• Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures on the managed side are not verified beyond the pattern checks.

Cost estimate

Estimated 10.00 USD per month (size prices from pricing.toml at build revision a1b8c38919e59cd035ebabaced73cf84ece24371).

• app server x1 s-1vcpu-1gb: 5.00 USD
• managed PostgreSQL database x1 s-1vcpu-1gb: 5.00 USD

Destination always-on monthly price of the tested sizes; apps auto-pause when idle. Source costs are unknown to Ample.

Verification evidence

• canary_run on 2026-09-21T01:14:18Z at revision 50dbac567d2c5cc8e55e6c748a646be0025d9cfb-dirty (CLI 0.1.21): Destination side verified: the FastAPI pattern fixture deployed on Ample (pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template) and its checks passed (the app built, started and answered on its public HTTPS URL with encrypted configuration delivered). The source-side export from Vercel app is documented from the vendor's standard tooling and was not executed by this catalog's evidence. (expires 2027-03-20T01:14:18Z)

Last verified: 2026-09-21T01:14:18Z

Execution binding

No execution binding. This recipe is documentation only; nothing is executed automatically.