Stock simulation app

How to run

The application can be started with a single command. If no port is provided, it defaults to 3000.

Linux / macOS (bash)

./start.sh [PORT]

If you encounter a permission error:

chmod +x ./start.sh

Then run the start command again.

Windows (PowerShell)

.\start.ps1 [PORT]

If script execution is blocked:

Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass

Then run the start command again.

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Once started, Docker creates containers for the application, database, and load balancer. Three application instances are launched and traffic is distributed between them via Nginx. Failed instances are automatically restarted.

Stack

• NestJS
• Redis
• Nginx
• Docker

/src structure

The app was build following the separation of concerns principle:

• main.ts – application entry point, bootstraps the NestJS app

• stock.module.ts – registers controllers and providers

• stock.controller.ts – defines HTTP endpoints and request handling

• stock.service.ts – contains business logic

• stock.service.spec.ts – unit tests for buySell function from the StockService

• stock.repository.ts – handles all Redis operations (data access layer)

• redis.service.ts – provides and manages the Redis client

• dtos/buy-sell.dto.ts – DTO for POST /wallets/{wallet_id}/stocks/{stock_name}

• dtos/set-stocks.dto.ts – DTO for POST /stocks

• dtos/dtos.validation.spec.ts – tests DTO validation and transformation rules

• pipes/parse-stock-name.pipe.ts – validates and normalizes stock name

• pipes/parse-wallet-id.pipe.ts – validates wallet id

• pipes/parse-stock-name.pipe.spec.ts – tests stock name pipe