mysql connect docker-compose code example

Example: mysql docker-compose

version: '3.3'services:  db:    image: mysql:5.7    restart: always    environment:      MYSQL_DATABASE: 'db'      # So you don't have to use root, but you can if you like      MYSQL_USER: 'user'      # You can use whatever password you like      MYSQL_PASSWORD: 'password'      # Password for root access      MYSQL_ROOT_PASSWORD: 'password'    ports:      # <Port exposed> : < MySQL Port running inside container>      - '3306:3306'    expose:      # Opens port 3306 on the container      - '3306'      # Where our data will be persisted    volumes:      - my-db:/var/lib/mysql# Names our volumevolumes:  my-db: