# Host appointment booking with Django: relational workflow state

## Summary
Deploy a appointment booking 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 appointment booking-specific behavior as your application code.

## Representative Queries
- Host appointment booking with Django: relational workflow state
- Where can I host Appointment booking built with Django?
- I need a domain record schema, validation rules and concurrency behavior.

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

## Infrastructure Requirements
### 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.

### 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 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

## Tested Configuration
- **Template**: python-3.12  
- **Runtime**: python  
- **Size**: s-1vcpu-1gb  
- **Install Command**: python3 -m pip install --target .ample/python -r requirements.txt  
- **Start Command**: 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. 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

## Success Checks
- **App responds on its public URL**: `GET /`, Expect: ample canary django patterns  
- **Transactional-workflows self-test**: `GET /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 appointment booking 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 (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
  - **Components**:
    - **App server**: size: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0  
    - **Managed PostgreSQL database**: size: 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.

## Next Actions
- **[Browse the catalog index](https://api.ample.computer/v1/catalog)**: Browse published recipes by intent, stack and constraints.
- **[Prepare a side-effect-free deployment plan for an authorized project](https://api.ample.computer/v1/catalog/plan)**: Inputs: {projectId:"", recipeId:"page:recipes:appointment-booking:django:relational-workflow", recipeRevision:"r1"}.