Migrate Heroku app: Express

Move Express compute from Heroku 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.

Overview

Source procedure:

Export config vars with heroku config -s -a into an env file kept out of the repository. Not migrated automatically: Heroku add-ons other than Postgres, release-phase scheduling, dyno autoscaling and Heroku Scheduler are not migrated; use --release-command for release tasks.

Cutover:

Add the custom domain with ample domain add, update DNS from the Heroku DNS target, keep the Heroku app until verified, then scale it down.

Rollback:

Keep the source untouched until you confirm; nothing at the source is changed or deleted by this guide.

Representative Queries

• Migrate Heroku 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.

Workflow Steps

1. Inventory the source
   List what Heroku app provides beyond the component you are moving. Out of scope here: Heroku add-ons other than Postgres, release-phase scheduling, dyno autoscaling and Heroku Scheduler are not migrated; use --release-command for release tasks.
2. Source step 1
   Export config vars with heroku config -s -a into an env file kept out of the repository
3. Source step 2
   Translate the Procfile web process into the start command (--start or the package manifest's start script); worker processes need a separate --kind worker service
4. Source step 3
   Note buildpacks and add-ons in use; managed databases replace Heroku Postgres, other add-ons need their own plan
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, update DNS from the Heroku DNS target, keep the Heroku app until verified, then scale it down.
8. Rollback
   Point DNS or configuration back to the source. The source was never modified; deletion is a separate, user-executed step after validation.

Prerequisites

• Authorized access to the Heroku 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

Limitations

• Documentation only: nothing is executed automatically and no execution binding is offered.
• The source-side procedure is documented from Heroku 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: Heroku add-ons other than Postgres, release-phase scheduling, dyno autoscaling and Heroku Scheduler are not migrated; use --release-command for release tasks.
• 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.