Using docker-compose and composing files

docker-compose.dev.yml

version: '3'

services:
  server:
    volumes:
      - ./server/src:/usr/src/app/src/
    command: npm run dev
      
  frontend:
    volumes:
      - ./frontend/src:/usr/src/app/src
      - ./frontend/public:/usr/src/app/public
    command: npm run start
    build: ./frontend
    ports:
      - 4000:3000
    links:
      - server