Docker compose a MERN app with MongoDB Atlas-CodePudding

I have created a MERN app with MongoDB Atlas such that node runs on port 3000 and react runs on 3001 and connected the node end points to react.

the Docker file for react is

FROM node:14

WORKDIR /usr/src/app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 3001

CMD ["npm", "start"]

and for nodeJS is

FROM node:14

WORKDIR /usr/src/app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 3000

CMD ["npm", "start"]

now the compose file is

services:
  react-app:
    image: react-app
    build: ./client
    stdin_open: true
    ports:
      - "3001:3001"
    networks:
      - mern-app

  node-web-api:
    image: node-web-api
    build: ./server
    ports:
      - "3000:3000"
    networks:
      - mern-app

networks:
  mern-app:
    driver: bridge

now when i am composing it everything is workfine it composing sucessfully but the react is running on port 3000 instead of 3001 how can i fix this issue??

CodePudding user response：

npm default port is 3000, so if you want to run in on another port you should change the command to:

npm start --port 3001

CodePudding user response：

It's fine to have multiple processes running in containers listening on the same port. The Docker-level settings you show in the question have no effect on whatever listen() call is in the application. (@MojtabaAhadi's answer discusses setting Node to listen on a different port.)

What you can do instead is set the application to listen on its normal port, but remap that in the Compose setup. In the Dockerfile, change:

EXPOSE 3000

to match the port the application actually listens on. (Or not, or delete this line entirely; it doesn't actually do anything in modern Docker.)

In the Compose file, for that container, the second ports: number needs to match what the application is listening on, and the first number is a host port that isn't otherwise in use. They don't need to be the same.

ports:
  - '3001:3000'

If host port 3001 is busy then you can change that first port number only without rebuilding your image or changing anything else in the container setup.