docker-compose.yml

#the docker compose file version
version: "3.7"
# you can run multiple services inside one docker compose file
# define them with their dependencies one after the other
services:
  # service 1 named react-dev
  react-dev:
    # service 1 container name
    container_name: react-dev
    build:
      # the context (working directory) is the current directory
      # change this to the directory containing the dockerfile if in a different place
      context: .
      # the dockerfile to be run
      dockerfile: Dockerfile
    # map the exposed port from the underlying service to a port exposed to the outside
    # in this case  map port 3000 exposed by create react app to also 3000
    # to be used to access the container from the outside
    ports:
      - "3000:3000"
    # the mounted volumes (folders which are outside docker but being used by docker)
    volumes:
      - ".:/app"
      - "/app/node_modules"
    # set the environment to development
    environment:
      - NODE_ENV=development