# Host asset library with Django: relational workflow state

Deploy a asset library built with Django 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 Django: 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 asset library-specific behavior as your application code.

## Resource Requirements
- Compute
- Postgres

## Tested Configuration
- **Template:** python-3.12
- **Runtime:** python
- **Size:** s-1vcpu-1gb

### Installation Command
```shell
python3 -m pip install --target .ample/python -r requirements.txt
```

### Start Command
```shell
PYTHONPATH=.ample/python:${PYTHONPATH:-} python3 run.py
```

## Workflow Steps
1. **Build and start**  
   `pip install into .ample/python from requirements.txt, then waitress serving project.wsgi from run.py reading PORT on the python-3.12 template.`

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).`

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.`  
   Command: `ample logs  --kind build`

## Limitations
- Verified on the python-3.12 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Django major versions are not verified.
- The asset library itself (your domain records, validation rules and concurrency policy) is application code and was not separately tested.

## Cost Estimate
- **Currency:** USD
- **Monthly Amount:** 10.0

### 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: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle.*

## Prerequisites
1. A Django project that builds and starts with the documented commands.
2. A PostgreSQL driver reading DATABASE_URL at runtime.
3. An Ample account token with the necessary permissions.