docker-compose.prod.yml

# docker-compose.yml
version: "3"
services:
  redis:
    image: redis
    container_name: redis-store
    expose:
      - 6379

  backend:
    build: ./backend
    ports:
      - 5000:5000
    links:
      - redis
    environment:
      # Change to production to reproduce prod issues
      - NODE_ENV=production
      # Defines what port to expose
      - PORT=5000
      # Since this is linked to the redis contnainer, we can do a DNS lookup by
      # name.
      - REDIS_URL=redis://redis-store:6379
      # MTD API key used in the Express server, pulled as an environment variable
      - CUMTD_API_KEY=$CUMTD_API_KEY
    command:
      sh -c 'npm run start:dev'

  frontend:
    build: 
      context: ./frontend
      dockerfile: Dockerfile-prod
    ports:
      - 3000:3000
    links:
      - redis
    depends_on:
      - redis
      - backend
    environment:
      - REACT_APP_API_PORT=5000
    command:
      # Despite being built off the prod image that has the compiled build, 
      # we are using the dev version because this will let us use localhost:PORT as the API endpoint
      # which gets baked into the prod image and is thus unaffected by env vars from this file
      sh -c 'npm start'
    stdin_open: true