# Migrate Vercel app: Express

## Summary

Move Express 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:** `node-22`
- **runtime:** `node`
- **size:** `s-1vcpu-1gb`
- **install:** `npm install`
- **build:** `npm run build --if-present`
- **start:** `npm run start`

## 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.** `npm install`, `npm run build --if-present`, `npm run start` on the node-22 template. Pass the exported variables with --env; keep the source running.
   
   ```
   ample deploy . --name <app-name> --public --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

- **Express pattern fixture (destination)** (tests/deploy-canaries/express-patterns): Verified destination basis: Express compute.

## Success checks

- destination app responds on its public URL (`/` on the live URL, expect ample canary express 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 node-22 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 2026-09-21T02:34:39Z at revision `1d28ae0-dirty (CLI 0.1.21)`: Destination side verified: the Express pattern fixture deployed on Ample (npm install, npm run build --if-present, npm run start on the node-22 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 2027-03-20T02:34:39Z)

## Execution binding

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