# Migrate Vercel app: Express

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.

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

## Resource Requirements
- Primitive: compute
- Primitive: postgres

## Infrastructure Requirements
- **Compute**  
  Status: verified  
  Summary: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
- **Postgres**  
  Status: verified  
  Summary: 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

## Workflow Steps
1. **Inventory the source**  
   List what Vercel app provides beyond the component you are moving.
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.
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
### Express pattern fixture (destination)
- Verified destination basis: Express 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.

## Cost Estimate
- Currency: USD
- Monthly Amount: 10.0
- Authoritative: true
- Basis: size prices from pricing.toml (loaded by the API)
- Components:
  - **App server**: size: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0
  - **Managed PostgreSQL database**: size: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0

## Evidence Summary
- **Canary Run**: Verified destination side: the Express 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.