FastAPI SqlAlchemy CockroachDB

This project aims to demonstrate the implementation of the following architectural patterns in Python.

• Model-View-Controller (MVC)
• Frontend/Backend segregation
• 15Factor
• Test-Driven Development

Architecture

The project is based on two main services:

• frontendservice: Frontend mixing ASGI (FastAPI) and WSGI (Flask/Dash) applications.
• backendservice: Restful API connected to a database running in a PostgreSQL compatible CockroachDB cluster.

Architecture	Instrumentation

Docker Desktop est également requis.

Initialization

Install Micromamba Copy the .env.example file and name it .env. Update the variables inside the .env file, the run the following command line to create the Python environment dedicated to the project.

source .env
micromamba create --name ${PROJECT_NAME} --channel conda-forge python=3.10 --yes

Activate the environment.

source .env
micromamba activate ${PROJECT_NAME}

Agencement de l'arborescence de répertoires

|-- deploy
|   |-- envoy               # Envoy Proxy manifests
|-- docs                    # Documentation
|-- hack                    # local execution scripts
|-- specs                   # Open API definitions
|-- src
|   |-- backend             # "backendservice" source code
|   |-- frontend            # "frontendservice" source code
|-- tests
|   |-- unit                # Unit tests
|   |-- integration         # Integration tests
|-- .env                    # Local variables required for local development
|-- docker-compose.yml      # Local execution environment
|-- pytest.ini              # PyTest configuration
|-- VERSION                 # Application version

Exécution des scripts

The hack contains scripts to managed the application lifecyle from the developer workstation.

• hack/init.sh Initialze the development environment (i.e. Environment variable, Python environment, etc.)
• hack/run.sh Build and locally executes the containerized using Docker Compose

Tests

Local

Two type of tests can be executed:

• src/backend/src/tests/unit: Unitest written using Pytest to validated the models and controllers
• tests/integration: Test written using Thundclient (Postman equivalent for VsCode)

Run the following command to start the Docker Compose environment.

hack/run.sh

From a second terminal session, run the following command to start and interactive session in the backend container.

docker compose exec -it --user 'root' backend /bin/bash

Run the following commands to run the unit tests.

# Modèles uniquement
pytest tests/unit/test_models.py

# Routes/Contrôlleurs uniquement
pytest tests/unit/test_route.py

# Tous les tests unitaires
pytest

Running the demo

Don't forget to initialize the environment variables (i.e. source .env)

Unit tests are using a SqlAlchemy fixed that load/unload the data in the database

Run the following command to populate

hack/run.sh

docker compose exec -it --user 'root' backend /bin/bash

python3 tests/populate.py

Explore the various Web UIs.

• CockroachDB: http://localhost:8080
• Jaeger ui: http://localhost:16686
• Envoy admin: http://localhost:8081
• FastAPI swagger: http://localhost:8001/v1/docs
• Webui: http://localhost:8000