hex-spell / snake-backend

Kotlin Snake game high-scores microservice, with caching and rate limitiing

Snake game high-scores

Learning Kotlin applications for backend

What it does

• Saves user high-scores
• Retrieves the best 10 of all time

Http api live demo

http://modularizar.com/snake-backend

Example request:

curl --request GET \
  --url http://modularizar.com/snake-backend \
  --header 'Content-Type: application/json'

---

Endpoints

GET /

• Returns array of { "id": Int, "username": String, "points": Int, "saved_at": String }

POST /

• Receives { "username": String, "points": Int }
• Returns new entity as { "id": Int, "username": String, "points": Int, "saved_at": String }

---

Environment variables (name, default value):

• HOST: localhost
• DB_HOST: localhost
• DB_NAME: snake
• DB_PORT: 3306
• DB_USER: root
• DB_PASSWORD: root
• REDIS_HOST: localhost
• REDIS_PORT: 6379

---

Additional features

• Rate limiting by IP
• cache
• validation

Tools used:

• Ktor for http server with routing
• Ktorm as database ORM
• MySQL database
• Gson as json serializer
• Redis with Jedis
• Docker

---

Hosting

(Using docker-compose)

services:
  reverse_proxy:
      container_name: reverse_proxy
      image: nginx:1.17.10
      depends_on:
        # {...} my other services
        - snake-backend
      volumes:
        - ./nginx/nginx.conf:/etc/nginx/nginx.conf
      ports:
        - "80:80"
  snake-backend:
      container_name: snake-backend
      build:
        context: ./snake-backend
      user: root
      depends_on:
        - mysql
        - redis
      environment:
        HOST: snake-backend
        DB_HOST: mysql
        DB_NAME: "snake"
        DB_PORT: "3306"
        DB_USER: "root"
        DB_PASSWORD: #shh
        REDIS_HOST: redis
        REDIS_PORT: "6379"
      restart: always
  
  mysql:
    image: mysql:8.0.13
    command: --default-authentication-plugin=mysql_native_password
    restart: always
    environment:
      # {...} super secret stuff, yknow
    volumes:
      - ./mysql-data:/var/lib/mysql
      - ./init:/docker-entrypoint-initdb.d
    ports:
      - "3306:3306"

  redis:
    image: "redis:alpine"

    command: redis-server

    ports:
      - "6379:6379"

    volumes:
     - ./redis-data:/var/lib/redis
     - ./redis.conf:/usr/local/etc/redis/redis.conf

Database init script

CREATE DATABASE IF NOT EXISTS `snake`;

use snake;

CREATE TABLE `players` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`username` varchar(40) COLLATE utf8mb4_unicode_ci NOT NULL,
`points` int(11) NOT NULL,
`saved_at` datetime DEFAULT NOW(),
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=44 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci