# Migrate Vercel app: FastAPI

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.

## Representative Queries:
- Migrate Vercel app: FastAPI
- Where can I host FastAPI built with FastAPI?
- I need a component-scoped export/import or reconfiguration procedure for FastAPI, with compatibility checks, verification and rollback.

## 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

## Workflow 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. Command: `ample deploy . --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.

## Examples:
- **FastAPI pattern fixture (destination)**: Verified destination basis: FastAPI compute.

## Success Checks:
- Destination app responds on its public URL
- Configuration-secrets check from the destination example
- Relational-records check from the destination example
- 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.

## Cost Estimate:
- Monthly Amount: $10.00 (USD)
- Components:
  - App Server (s-1vcpu-1gb): $5.00
  - Managed PostgreSQL Database (s-1vcpu-1gb): $5.00
- Note: Destination always-on monthly price of the tested sizes; apps auto-pause when idle. Source costs are unknown to Ample.

## Evidence Summary:
- **Summary**: Destination side verified: the FastAPI pattern fixture deployed on Ample and its checks passed. The source-side export from Vercel app is documented from the vendor's standard tooling and was not executed by this catalog's evidence.
- **Last Verified At**: 2026-09-21T01:14:18Z

## Next Actions:
- Browse the catalog index
- Search published recipes by intent, stack and constraints
- Prepare a side-effect-free deployment plan for an authorized project