## Host approval workflow with FastAPI: downloadable reports

Deploy an approval workflow built with FastAPI on Ample using the generated downloads 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, a private S3-compatible bucket holds objects with credentials delivered as encrypted environment variables. Verified on FastAPI: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). Not separately tested: your export formats, retention policy, and entitlement model; treat the approval workflow-specific behavior as your application code.

### Representative Queries
- Host approval workflow with FastAPI: downloadable reports
- Where can I host an Approval workflow built with FastAPI?
- I need an export query, generated artifact retention, and authorized download flow.

### Infrastructure Requirements
- **Compute**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
- **Postgres**: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.
- **S3-compatible object storage**: Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary.

### 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 generated downloads: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller.
3. **Wire object storage**: Create the bucket(s), then pass endpoint, region, bucket and keys as --env values. Use path-style addressing. Keep private data in an unpublished bucket.
4. **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.
5. **Verify**: Fetch the live URL and the pattern self-test route(s) from the example; then run your own checks.

### 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 approval workflow itself (your export formats, retention policy, and entitlement model) is application code and was not separately tested; the pattern checks are what was verified.

### Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 10.0
- **Components**: 
  - App server: 1.0 at 5.0 
  - Managed PostgreSQL database: 1.0 at 5.0

### Evidence Summary
- **Canary Run**: FastAPI pattern fixture deployed on Ample; checks passed for generated-downloads and configuration-secrets. Pattern proof: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller.
  - Observed At: 2026-09-21T01:14:18Z
  - Expires At: 2027-03-20T01:14:18Z

### Next Actions
- **Browse Catalog**: Browse the catalog index.
- **Search Recipes**: Search published recipes by intent, stack, and constraints.
- **Plan Deployment**: Prepare a side-effect-free deployment plan for an authorized project.