# Host Subscription Content with Django: Relational Catalog Data

## Summary  
Deploy a subscription content built with Django on Ample using the transactional workflows pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, and 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).

## Resource Requirements  
- **Compute**  
- **Postgres**

## 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.

## Prerequisites  
- A Django project that builds and starts with the documented commands (pip install into .ample/python from requirements.txt, then waitress serving project.wsgi 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

## 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. 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`

## 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

## Success Checks  
1. App responds on its public URL.
   - Kind: http_get
   - Path: /  
   - Expect: ample canary django 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 Django major versions are not verified.  
- The subscription content 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  
- **Basis**: Size prices from pricing.toml at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty  
  - Components:
    - **App server**: s-1vcpu-1gb, Quantity: 1.0, Monthly Amount: 5.0  
    - **Managed PostgreSQL database**: 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. Buckets are allocation-priced per quota and not included.