The single most important architectural property: the workflow engine is database-driven. Processing steps, transitions, conditions, pricing rules and notifications are configuration — never hard-coded business logic.

Architecture

apps/
├── core/            # base models, error envelope, pagination
├── accounts/        # User (JWT auth), Customer profile (Odoo-keyed identity)
├── rbac/            # Role / Permission / UserRole + DRF permission classes
├── reservations/    # Slot availability, double-booking prevention
├── orders/          # ProcessingOrder + immutable snapshots + order numbers
├── workflows/       # Workflow / Version / Step / Transition + engine
├── processing/      # StepExecution state machine + rework
├── pricing/         # PricingRule + PricingEngine (backend-authoritative)
├── payments/        # Payment + gateway abstraction (idempotent)
├── invoicing/       # Invoice + Odoo sync state machine + Celery task
├── notifications/   # Templates, rules, SMS provider abstraction
├── reports/         # Dynamic report fields
├── live_monitoring/ # Cameras, streams, per-step authorization
├── audit/           # Immutable audit log
└── integrations/    # odoo/ client + services (mock-backed when unconfigured)

Key service/domain classes:

apps.workflows.engine.WorkflowEngine — version validation, publish, condition evaluation, transition availability.
apps.pricing.engine.PricingEngine — full price breakdown with snapshots.
apps.reservations.services.ReservationService — availability + locking.
apps.processing.services.ProcessingService — step state machine + rework.

Requirements

Python 3.11+
PostgreSQL (optional for local dev — SQLite is used when DATABASE_URL is unset)

Setup

cd cetana-backend
python -m venv .venv
# Windows: .venv\Scripts\activate   |  Linux/macOS: source .venv/bin/activate
pip install -r requirements.txt

cp .env.example .env   # then edit secrets
python manage.py migrate
python manage.py seed_demo
python manage.py runserver

Environment variables

See .env.example. Important ones: SECRET_KEY, DEBUG, ALLOWED_HOSTS, DATABASE_URL, ODOO_*, PAYMENT_GATEWAY_*, SMS_PROVIDER_*, CELERY_BROKER_URL, BASE_CURRENCY. Secrets are never committed.

Workers

celery -A config worker -l info
celery -A config beat -l info

Tests

python manage.py test

API

Auth: POST /api/v1/auth/login/ (JWT), POST /api/v1/auth/refresh/
Workflows: /api/v1/workflows/, /api/v1/workflows/versions/, /api/v1/workflows/steps/, /api/v1/workflows/transitions/, POST /api/v1/workflows/{id}/publish/
Reservations: /api/v1/reservations/, /api/v1/reservations/slots/
OpenAPI: /api/v1/schema/, Swagger UI: /api/v1/docs/

Docker

From the repository root:

docker compose up -d

Production notes

Use PostgreSQL (DATABASE_URL), set a strong SECRET_KEY, DEBUG=0, restrict ALLOWED_HOSTS and CORS_ALLOWED_ORIGINS.
Run with gunicorn behind a reverse proxy; configure secure headers there.
Keep Odoo / payment / SMS / camera credentials in environment variables.