Migrate Fly.io app: Rails

Summary

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.

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 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

Exact tested configuration

• template: ruby-3.4
• runtime: ruby
• size: s-1vcpu-1gb
• install: bundle config set --local path vendor/bundle && bundle config set --local without 'development test' && bundle install
• start: bundle exec rails server -b 0.0.0.0 -p $PORT

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.

   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, 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.

Tested examples

• Rails pattern fixture (destination) (tests/deploy-canaries/rails-patterns): Verified destination basis: Rails compute.

Success checks

• destination app responds on its public URL (/ on the live URL, expect ample canary rails 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 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.

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 2026-09-20T21:55:28Z at revision 4f7cb9813c1f-dirty (CLI 4f7cb98): Destination side verified: the Rails pattern fixture deployed on Ample (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) and its checks passed (the app built, started and answered on its public HTTPS URL with encrypted configuration delivered). The source-side export from Fly.io app is documented from the vendor's standard tooling and was not executed by this catalog's evidence. (expires 2027-03-19T21:55:28Z)

Last verified: 2026-09-20T21:55:28Z

Execution binding

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