# Migrate Fly.io app: Rails

Move Rails compute from Fly.io 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 secrets and env from `fly.toml` [env] and `fly secrets list` (values must come from your own records; Fly does not reveal secret values). Not migrated automatically: Multi-region placement, Fly Machines API, volumes and 6PN private networking are not migrated; region is an unknown fact on Ample.

## Cutover:
Add the custom domain with `ample domain add`, update DNS from the Fly target, keep the Fly app until verified, then scale it to zero.

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

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

### Resource Requirements
- **Compute**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
- **Postgres**: 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 Fly.io 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 Fly.io app provides beyond the component you are moving. Out of scope here: Multi-region placement, Fly Machines API, volumes and 6PN private networking are not migrated; region is an unknown fact on Ample.
2. **Source step 1**: Export secrets and env from `fly.toml` [env] and `fly secrets list` (values must come from your own records; Fly does not reveal secret values).
3. **Source step 2**: Translate `fly.toml` services and the Dockerfile or buildpack into a Node or Python source deploy; Ample builds from source on its templates.
4. **Source step 3**: Note Fly-only features in use: multi-region placement, machines API, volumes, private networking.
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.
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 Fly target, keep the Fly app until verified, then scale it to zero.
8. **Rollback**: Point DNS or configuration back to the source. The source was never modified; deletion is a separate, user-executed step after validation.

### Limitations
- Documentation only: nothing is executed automatically and no execution binding is offered.
- The source-side procedure is documented from Fly.io 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: Multi-region placement, Fly Machines API, volumes and 6PN private networking are not migrated; region is an unknown fact on Ample.
- 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.