MERN 堆栈无法将数据库连接到 Docker 容器

Question

Good day... regarding for integration the MERN stack web application on docker using dockerfiles and docker-compose.yml.. the localhost:8000 is where my backend, also localhost:3000 is where my frontend ports..and i'm running it on locally.. the credentials on mongo is correct..then i put networks in docker-compose and driver: "bridge", there are on the same network.. after i build container and running the application on docker.. the error stated below:

[0] [http-server] listening: http://localhost:8000/
[1] ℹ ｢wds｣: Project is running at http://172.20.0.3/
[1] ℹ ｢wds｣: webpack output is served from
[1] ℹ ｢wds｣: Content not from webpack is served from /maint/client/public
[1] ℹ ｢wds｣: 404s will fallback to /
[1] Starting the development server...
[1]
[0] connect ECONNREFUSED 127.0.0.1:27017
[0] ERROR: Cannot connect to the database
[0] Exiting now...
[0] [nodemon] app crashed - waiting for file changes before starting...

my dockerfiles :

# get the base node image
FROM node:10.15.2

# set the working dir for container
WORKDIR /maint

# copy the json file first
COPY ./package.json /maint

RUN "npm ci"

# copy other project files
COPY . .

# build the folder
CMD [ "npm", "run", "start" ]

and inside of my docker-compose-local.yml

version: '3'
services:
    maint:
      build:
        context: .
        dockerfile: Dockerfile.dev
      command: npm run dev
      container_name: mat-docker
      volumes:
        - ./:/maint
        - /maint/node_modules
      ports:
        - "3000:3000"
      depends_on:
        - mongo
      networks:
        - app-network
    mongo:
      image: mongo
      container_name: mat-dockerdb
      ports:
        - "27017:27017"
      env_file: .env
      environment:
        - MONGO_HOST:$MONGO_HOST
        - MONGO_DB:$MONGO_DB
        - MONGO_USERNAME:"admin"
        - MONGO_PASSWORD:"password123"
      networks:
        - app-network

networks:
  app-network:
    driver: bridge

Answer 1

You can do this much easier by just using the host network. This way your main service and mongo instance use the same host network as your backend. Here is an example of a docket compose app to do this

 version: "2"
 services:
 app:
    container_name: app
    network_mode: host
    restart: always
    build: .
    ports:
      - "3000:3000”
    depends_on:
      - mongo
 mongo:
    container_name: mongo
    image: mongo
    network_mode: host
    volumes:
      - ./data:/data/db
    ports:
      - "27017:27017"