Migrate Fly.io app: FastAPI

Summary

Move FastAPI 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.

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

Infrastructure Requirements

Compute

• Primitive ID: primitive:compute
• Label: 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

• Primitive ID: primitive:postgres
• Label: 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.

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
   pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template. Pass the exported variables with --env; keep the source running.
   Command: ample deploy . --name --public --start "python3 run.py" --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.

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 python-3.12 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
• Authoritative: true
• Basis: size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
• Components:
  • Name: app server
    • Size: s-1vcpu-1gb
    • Quantity: 1.0
    • Monthly Amount: 5.0
  • Name: managed PostgreSQL database
    • Size: 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.

Examples

• Title: FastAPI pattern fixture (destination)
  Description: Verified destination basis: FastAPI compute.
  Source Reference: tests/deploy-canaries/fastapi-patterns

Success Checks

1. Description: destination app responds on its public URL
   Kind: http_get
   Path: /
   Expect: ample canary fastapi patterns
2. Description: configuration-secrets check from the destination example
   Kind: http_get
   Path: /p/configuration-secrets
   Expect: see the pattern fixture checks
3. Description: relational-records check from the destination example
   Kind: http_get
   Path: /p/relational-records
   Expect: see the pattern fixture checks
4. Description: data or object counts and checksums match the source
   Kind: manual
   Expect: operator comparison before cutover.