# Connect Postgres for Starlette

## Summary
Database connection for a Starlette app on Ample. Verified on Starlette: a managed PostgreSQL database auto-provisioned and injected as DATABASE_URL, with real queries succeeding at request time (records=ok). Build and start: `pip install into .ample/python from requirements.txt`, then `uvicorn from run.py` reading PORT on the python-3.12 template.

## Prerequisites
- A Starlette project (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
- An Ample account token with servers:write, databases:read

## Resource 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.

## Workload 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. **Read DATABASE_URL at runtime**  
   Open connections from the environment inside handlers or a pool; omit DATABASE_URL to auto-provision a managed database or pass `--env DATABASE_URL=...` for an existing one.
3. **Verify**  
   Fetch the live URL and `/p/relational-records` on the example; on failure read the build and runtime logs. `ample logs  --kind build`

## Success Checks
- App responds on its public URL: `ample canary starlette patterns`
- Relational-records check from the example: see the pattern fixture checks.

## Limitations
- Verified on the python-3.12 template at s-1vcpu-1gb; other sizes and Starlette major versions are not verified.
- Region, compliance attestations and request-duration limits are unknown and not claimed.
- Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified.

## 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: 1 s-1vcpu-1gb - $5.00  
- Managed PostgreSQL database: 1 s-1vcpu-1gb - $5.00

> Note: Always-on monthly price of the tested sizes; apps auto-pause when idle. Buckets are allocation-priced per quota and not included.

## Examples
- **Starlette pattern fixture**: Verified database connection on Starlette. Source Ref: tests/deploy-canaries/starlette-patterns.

## 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`

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

## Evidence Summary
- Starlette pattern fixture deployed on Ample; for this guide: a managed PostgreSQL database auto-provisioned and injected as DATABASE_URL, with real queries succeeding at request time (records=ok). Observed At: 2026-09-21T01:21:36Z.