PenQuiz

PenQuiz is a trivia PvP game which is set in Antarctica. The game consists of 3 different stages with multiple rounds and requires 3 people per match to play. The core concept of the game is to capture territories from other players by answering trivia questions. The end score of a game is calculated by the amount of territories you control.

This repository contains all the backend logic and kubernetes configuration files for the PenQuiz project. The front-end React Native repository is located here.

Table of contents

1. Features
2. Production
3. Game rules
4. Architecture
5. Backend stack
6. Run local production cluster

Features

• Engaging trivia battles
• Public matchmaking
• Private lobbies
• Match history and statistics
• Submit your own questions to the game
• Login with Google account
• Admin panel

Production

The production backend is hosted on Azure, while the frontend React Native application is hosted on Netlify. The RabbitMQ provider we use is CloudAMQP.

Visit the fully working game at https://penquiz.netlify.app/

Game rules

Architecture

The backend consists of 3 microservices which utilize RabbitMQ and GRPC to communicate with each other and send messages via SignalR to the frontend React Native application.

Backend stack:

• NET 5
• SQL Server / PostgreSQL (Entity ORM)
• CockroachDB
• SignalR
• GRPC
• JWT Authentication
• RabbitMQ
• Docker
• Kubernetes

Communication between Microservices

Embracing eventual consistency pattern, we use the RabbitMQ message bus to send messages between the microservices and we "pull" for any missing data whenever a microservice starts.

Run local production cluster

If you want to run PenQuiz locally with Kubernetes you need the following pre-requisites:

• Docker Desktop installed
• Kubernetes enabled in docker desktop

Create a namespace for the cluster if you don't want it to be stored in the default one

Create MSSQL Secret

kubectl create secret generic mssql --from-literal=SA_PASSWORD="yourpassword"

Apply all configuration files

In the K8S Folder run this command:

kubectl apply -f .

This will generate all services, deployments, keel.sh, a persistant volume claim and an nginx ingress controller.

There is a possibility that some deployments will not be registered, so make sure to verify if all services in the K8S directory are running

You can then access the backend production web server on https://localhost/api/account If you issued a self-signed SSL certificate you'd be prompted to allow access to this URL

Add ConfigMaps for deployment environmental variables

Each microservice has multiple environmental variables which are usually stored in an appsettings.json, however for docker we inject them through a ConfigMap. There are 3 example configmaps in the K8S directory. Add your own secrets, endpoints etc. and apply them.

Microservices endpoints

There are currently 3 microservices running on a single node:

• AccountService - {host}/api/account
• GameService - {host}/api/game
• QuestionService - {host}/api/question

Backend is also using Keel.sh to poll dockerhub for new container images and redeploys a service if it finds a new digest.

Use https

The kubernetes cluster doesn't communicate with HTTPS between the pods, however if you want to expose it to the public you have to make sure that the public IP has valid HTTPS. We use Cert Manager to manage our SSL Certificates

kubectl apply --validate=false -f cert-manager.yaml

If you want a self-signed certificate you need to apply these 2 files in the selfsigned directory

kubectl apply -f issuer.yaml
kubectl apply -f certificate.yaml

Open to public

If you want to expose the K8S cluster to the public you need to either connect a DNS through google or use tunneling when port forwarding isn't available on the machine (ISP blocking it)

To open it through tunnel you can use NGrok

ngrok http -region=eu 443