Black Mushroom

A very simple BlackJack game built with Nameko microservices framework.

Design considerations

Enable code reuse where possible (Deck is generic, Player is generic, Game is project specific).
Enable horizontal scaling by keeping services loosely coupled, seperate databases too.
This is a tech demo so it was smashed out quickly, this is not an excuse but there be dragons.
Service must operate over RPC.
Make it easy to switch database engine.
Use migrations to avoid having to manually mess with a database (what year is it?)
Test coverage is unacceptable, this is not a real world project.
I ran out of time to implement the various Docker containers but these would have been:
1. Postgres container for each service.
2. Application container for each service.
3. RabbitMQ container.
4. Some sort of load balancer such as Traefik
I would have also liked to explore adding an HTTP / WebSocket API.
If this was a real project I would have built a proper frontend for it (probably with React.JS)

Requirements

Core requirements

SQLAlchemy - 1.1.9
SQLAlchemy-Utils - 0.32.14
Nameko - 2.5.4
Nameko-SQLAlchemy - 0.1.0
Marshmallow - 2.13.5
Marshmallow-SQLAlchemy - 0.13.1
Alembic - 0.9.1

Database driver

You will need a database driver, the default is psycopg2 but you could use sqlite or whatever.

Psycopg2 - 2.7.1

Test requirements

py.test - 3.0.7

Install

Install requirements

You can install the wrapper package:

pip install .

You must then also install the services

pip install src/services/base
pip install src/services/decks
pip install src/services/games
pip install src/services/players

Database migrations

To create / update the database schema run the following command:

python black_mushroom/migrate.py

Running

Run all services

nameko run black_mushroom.app --config black_mushroom/config.yml

Running individual services

Run one or more of the following commands:

nameko run black_mushroom.players.services --config config.yml
nameko run black_mushroom.decks.services --config config.yml
nameko run black_mushroom.games.services --config config.yml

Usage

You can interact with this application by using the Nameko shell, run the following:

nameko shell --config config.yml

This gives you a prompt back which you can use to call services for example to start a game:

n.rpc.game.create(n.rpc.player.create('Chris'))

After running the above command you should get a game_id returned, you can interact with the game like so:

n.rpc.game.hit(YOUR_GAME_ID_HERE)

or alternatively you could choose to stick

n.rpc.game.stick(YOUR_GAME_ID_HERE)

Which should return you a JSON representation of the game state.

Testing

You can install the test requirements by running:

pip install -r requirements.txt

When running tests you can pass database test url with --test-db-url parameter or override db_url fixture.

With in-memory SQLite database

py.test black_mushroom/tests.py

With seperate test database

py.test src/black_mushroom/tests.py --test-db-url=sqlite:///test_db.sql

Docker

Each service can be run in an independent Docker container, all dependencies (e.g. PostgreSQL, RabbitMQ etc) can be run as Docker containers. This is all handled by a docker-compose file.

If you would like to start all services under Docker please run the following command:

docker-compose run --rm wait_for_rabbit && docker-compose up

hairychris/black-mushroom