Migrate AWS EC2 app: FastAPI

Summary

Move FastAPI compute from AWS EC2 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: Collect the process environment from the instance (systemd unit or process manager config) into an env file kept out of the repository. Not migrated automatically: Cron jobs, local files on the instance disk, security-group networking and IAM instance roles are not migrated; use managed databases, buckets and encrypted env instead.

Cutover: Add the custom domain with ample domain add, update DNS from the instance or load balancer, keep the instance until verified, then stop it.

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 AWS EC2 app provides beyond the component you are moving. Out of scope here: Cron jobs, local files on the instance disk, security-group networking and IAM instance roles are not migrated; use managed databases, buckets and encrypted env instead.

2. Source step 1
   Collect the process environment from the instance (systemd unit or process manager config) into an env file kept out of the repository.

3. Source step 2
   Replace the instance's process manager with the repository's start command; Ample supervises the process and restarts it.

4. Source step 3
   Inventory what else runs on the instance: databases, cron, reverse proxy rules, local files.

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 instance or load balancer, keep the instance until verified, then stop it.

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 AWS EC2 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 AWS EC2 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: Cron jobs, local files on the instance disk, security-group networking and IAM instance roles are not migrated; use managed databases, buckets and encrypted env instead.
• 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
• Basis: size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
• Components:
  • App server: size s-1vcpu-1gb, quantity 1.0, monthly amount 5.0
  • 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.

Success Checks

1. Destination app responds on its public URL

   • Kind: http_get
   • Path: /
   • Expect: ample canary fastapi patterns

2. Configuration-secrets check from the destination example

   • Kind: http_get
   • Path: /p/configuration-secrets
   • Expect: see the pattern fixture checks

3. Relational-records check from the destination example

   • Kind: http_get
   • Path: /p/relational-records
   • Expect: see the pattern fixture checks

4. Data or object counts and checksums match the source

   • Kind: manual
   • Expect: operator comparison before cutover.