page:migrate:heroku app:rails

Migrate Heroku app: Rails

Move Rails 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.

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.

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: bundle install into vendor/bundle from Gemfile.lock (development and test groups skipped), then Puma via rails server reading PORT on the ruby-3.4 template with RAILS_ENV=production. Pass the exported variables with --env; keep the source running.
   • Command: ample deploy . --name <your-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, 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.

Examples

• Rails pattern fixture (destination): Verified destination basis: Rails 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 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 ruby-3.4 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

• Currency: USD
• Monthly Amount: 10.0
• Basis: Size prices from pricing.toml at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
• Components:
  • App server: s-1vcpu-1gb (Quantity: 1.0, Monthly Amount: 5.0)
  • Managed PostgreSQL database: s-1vcpu-1gb (Quantity: 1.0, Monthly Amount: 5.0)
• Note: Destination always-on monthly price of the tested sizes; apps auto-pause when idle. Source costs are unknown to Ample.