# Host CSV Import Tool with FastAPI: Relational Workflow State

## Summary
Deploy a CSV import tool built with FastAPI on Ample using the transactional workflows pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, a managed PostgreSQL 16 database is auto-provisioned and injected as DATABASE_URL. Verified on FastAPI: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected). Not separately tested: your domain records, validation rules, and concurrency policy; treat the CSV import tool-specific behavior as your application code.

## Representative Queries
- Host CSV import tool with FastAPI: relational workflow state
- Where can I host CSV import tool built with FastAPI?
- I need a domain record schema, validation rules, and concurrency behavior.

## Resource Requirements
- primitive: compute
- primitive: postgres

## Infrastructure Requirements
1. **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.

2. **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.

## Prerequisites
- A FastAPI project that builds and starts with the documented commands (pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template)  
- A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env)  
- An Ample account token with servers:write, databases:read

## Tested Configuration
- **Template**: python-3.12  
- **Runtime**: python  
- **Size**: s-1vcpu-1gb  
- **Install**: `python3 -m pip install --target .ample/python -r requirements.txt`  
- **Start**: `PYTHONPATH=.ample/python:${PYTHONPATH:-} python3 run.py`

## Workflow Steps
1. **Build and Start**  
   - `pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template. The server must bind 0.0.0.0 on PORT.`

2. **Implement the Pattern on PostgreSQL**  
   - The fixture's module implements transactional workflows: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected). Copy the approach into your schema; keep migrations idempotent and run them with --release-command.

3. **Deploy**  
   - Run the synchronous deploy once and read the result (exit 0 live, 1 failed, 2 blocked). Re-running with no change is a no-op.
   - Command: `ample deploy . --name  --public --start "python3 run.py"`

4. **Verify**  
   - Fetch the live URL and the pattern self-test route(s) (/p/transactional-workflows) from the example; then run your own checks. On failure read `ample logs  --kind build` then `--kind runtime`.
   - Command: `ample logs  --kind build`

## Examples
- **FastAPI Pattern Fixture**  
  Multi-pattern FastAPI app whose transactional workflows module was checked live; the module is under tests/deploy-canaries/_pattern-modules.
  - **Source Ref**: tests/deploy-canaries/fastapi-patterns

## Success Checks
1. The app responds on its public URL.
   - **Kind**: http_get  
   - **Path**: /  
   - **Expect**: ample canary fastapi patterns

2. Transactional-workflows self-test.
   - **Kind**: http_get  
   - **Path**: /p/transactional-workflows  
   - **Expect**: tx=ok history=2 conflict=rejected

## Limitations
- Verified on the python-3.12 template at s-1vcpu-1gb with the example fixture; other sizes, templates, and FastAPI major versions are not verified.
- The CSV import tool itself (your domain records, validation rules, and concurrency policy) is application code and was not separately tested; the pattern checks are what was verified.
- Region, compliance attestations, and request-duration limits are unknown and not claimed.
- Apps auto-pause when idle and wake on the next request; always-on is an operator setting, not a plan feature.
- Managed PostgreSQL 16 only; extensions, connection limits, and backup or restore procedures are not verified; apps and their databases are placed together.

## Cost Estimate
- **Currency**: USD  
- **Monthly Amount**: 10.0  
- **Components**:  
   - App server: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0  
   - Managed PostgreSQL database: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0  
- Note: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle.

## Evidence Summary
1. **Canary Run**  
   Summary: 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); checks passed for transactional-workflows and configuration-secrets. 
   - **Observed At**: 2026-09-21T01:14:18Z  
   - Scope:  
     - Checks: [/p/transactional-workflows]  
     - Pattern: pattern:transactional-workflows  
     - Template: python-3.12

2. **Canary Run**  
   Summary: The same FastAPI app deployed with a --release-command migration; the marker it created was readable after activation.
   - **Observed At**: 2026-09-20T01:54:51Z  
   - Scope:  
     - Pattern: pattern:transactional-workflows

## Last Verified At
- **Date**: 2026-09-21T01:14:18Z

## Unknowns
- Region availability is unknown until a verified region fact is recorded.
- Compliance attestations are unknown; none are claimed.

## Formats
- [HTML](/content/recipes/csv-import-tool/fastapi/relational-workflow/index.html)
- [Markdown](/content/recipes/csv-import-tool/fastapi/relational-workflow.md)
- [JSON](https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Acsv-import-tool%3Afastapi%3Arelational-workflow)

## Next Actions
1. **Browse the Catalog Index**  
   - Operation: `GET /v1/catalog`

2. **Search Published Recipes by Intent, Stack, and Constraints**  
   - Operation: `POST /v1/catalog/search`
   - Parameters: `{ "limit": 5, "query": "Host csv import tool with FastAPI: relational workflow state" }`

3. **Prepare a Side-Effect-Free Deployment Plan for an Authorized Project**  
   - Operation: `POST /v1/catalog/plan`
   - Parameters: `{ "inputs": {}, "projectId": "", "recipeId": "page:recipes:csv-import-tool:fastapi:relational-workflow", "recipeRevision": "r1" }`

4. **Read the Existing Agent Authentication Setup**  
   - Operation: `GET /mcp/setup`

5. **Browse CSV Import Tool**  
   - Operation: `GET /v1/catalog/nodes/workload%3Acsv-import-tool`

6. **Browse FastAPI**  
   - Operation: `GET /v1/catalog/nodes/stack%3Aframework-fastapi`

7. **Browse Transactional Workflows**  
   - Operation: `GET /v1/catalog/nodes/pattern%3Atransactional-workflows`

8. **Browse Deploy Web App**  
   - Operation: `GET /v1/catalog/nodes/intent%3Adeploy-web-app`