连接两个docker容器nodejs和mongodb

我正在尝试使用网络泊坞窗连接两个容器，但是由于某种原因，我遇到了错误:

I'm trying to connect two conainers using networks docker, but for some reason I'm getting a error:

MongoNetworkError:首次连接时无法连接到服务器[db:27017] [Error:connect ECONNREFUSED 172.22.0.3:27017

MongoNetworkError: failed to connect to server [db:27017] on first connect [Error: connect ECONNREFUSED 172.22.0.3:27017

有什么建议吗?

谢谢！

docker-compose.yml

docker-compose.yml

version: '3'

services:
  nodejs:
    build:
      context: .
      dockerfile: Dockerfile.dev
    image: nodejs
    container_name: nodejs
    restart: unless-stopped
    env_file: 
      - .env
    environment:
      - MONGO_USERNAME=$MONGO_USERNAME
      - MONGO_PASSWORD=$MONGO_PASSWORD
      - MONGO_HOSTNAME=db
      - MONGO_PORT=$MONGO_PORT
      - MONGO_DB=$MONGO_DB 
    ports:
      - "3000:3000"
    volumes:
      - .:/home/node/app
      - node_modules:/home/node/app/node_modules
    networks:
      - app-network
    command: /home/node/app/node_modules/.bin/nodemon app.js
  db:
    image: mongo:4.2.9-bionic
    container_name: db
    restart: unless-stopped
    env_file: 
      - .env
    environment: 
      - MONGO_INITDB_ROOT_USERNAME=$MONGO_USERNAME
      - MONGO_INITDB_ROOT_PASSWORD=$MONGO_PASSWORD
    volumes:
      - dbdata:/data/db
    networks:
      - app-network
networks:
  app-network:
    driver: bridge
volumes:
  dbdata:
  node_modules: