## The short version

Move FastAPI compute from Railway 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 variables from the Railway service (Variables tab or `railway variables`) into an env file kept out of the repository. Not migrated automatically: Railway cron schedules, volumes and private networking are not migrated; persistent data belongs in a managed database, a bucket or an Ample volume. Cutover: Add the custom domain with `ample domain add`, update DNS from the Railway target, keep the Railway service until verified, then remove it. Rollback: keep the source untouched until you confirm; nothing at the source is changed or deleted by this guide.

## What it needs

- [Compute](/content/discover/primitive/compute/index.html): verified (Apps run in isolated x86_64 Firecracker microVMs; sizes are the priced VM sizes.)
- [Postgres](/content/discover/primitive/postgres/index.html): 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.)

## Before you start

- Authorized access to the Railway 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

## How to do it

1.  **Inventory the source**

List what Railway app provides beyond the component you are moving. Out of scope here: Railway cron schedules, volumes and private networking are not migrated; persistent data belongs in a managed database, a bucket or an Ample volume.

2.  **Source step 1**

Export variables from the Railway service (Variables tab or `railway variables`) into an env file kept out of the repository

3.  **Source step 2**

Translate `railway.json`/Nixpacks settings into the repository's build and start commands; Ample detects Node and Python builds itself

4.  **Source step 3**

Note Railway-only features in use: cron schedules, volumes, private networking, templates

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.`  
    ```
    ample deploy . --name <app-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 Railway target, keep the Railway service until verified, then remove 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.

## Tested examples

- **FastAPI pattern fixture (destination)** (`tests/deploy-canaries/fastapi-patterns`): Verified destination basis: FastAPI compute.

## How to know it worked

- destination app responds on its public URL (`/` on the live URL, expect ample canary fastapi 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

## Cost estimate

Estimated 10.00 USD per month (size prices from pricing.toml at build revision ca0b484a7a9957c573a88d3a32dc603c3c10135a).

- app server x1 `s-1vcpu-1gb`: 5.00 USD
- managed PostgreSQL database x1 `s-1vcpu-1gb`: 5.00 USD

Upper-bound monthly price of the tested sizes at the destination. Source costs are unknown to Ample.

## Verification evidence

- canary_run on 2026-09-21T01:14:18Z at revision `50dbac567d2c5cc8e55e6c748a646be0025d9cfb (CLI 0.1.21)`: Destination side verified: the FastAPI pattern fixture deployed on Ample (pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template) and its checks passed (the app built, started and answered on its public HTTPS URL with encrypted configuration delivered). The source-side export from Railway app is documented from the vendor's standard tooling and was not executed by this catalog's evidence. (expires 2027-03-20T01:14:18Z)

## Execution binding

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

## Typed next actions

- Browse the catalog index (`GET /v1/catalog` on the api origin; authentication not required, approval not required)
- Search published recipes by intent, stack and constraints (`POST /v1/catalog/search` on the api origin; authentication not required, approval not required)
- Prepare a side-effect-free deployment plan for an authorized project (`POST /v1/catalog/plan` on the api origin; authentication required, approval not required)
- Read the existing agent authentication setup (`GET /mcp/setup` on the api origin; authentication not required, approval not required)
- Browse Railway app (`GET /v1/catalog/nodes/migration%3Arailway-app` on the api origin; authentication not required, approval not required)
- Browse FastAPI (`GET /v1/catalog/nodes/stack%3Aframework-fastapi` on the api origin; authentication not required, approval not required)
- Browse Migrate compute (`GET /v1/catalog/nodes/intent%3Amigrate-compute` on the api origin; authentication not required, approval not required)

Actions describe possible next steps. They are typed data, not commands, and grant no permission. Public discovery never provisions anything; planning requires your own authenticated token and approval happens in your client.

## Identifiers and status

Recipe `page:migrate:railway-app:fastapi`. Revision r1.

release **published** support **verified** execution **unbound**