docker cannot start MYSQL service-CodePudding

does anyone have any idea about this error? I am trying to deploy a swarm stack with mysql:8 image and I got this error the MySQL service stopped and not started. kindly check the DB service below

version: "3.7"
services:
  app:
    image: 127.0.0.1:5000/app
    working_dir: /var/www/html
    volumes:
      - ./:/var/www/html
    networks:
      - backend
    deploy:
     replicas: 5
     restart_policy:
      condition: on-failure   

  db:
    image: mysql:8
    environment:    
      MYSQL_DATABASE: ROUTE
      MYSQL_ROOT_PASSWORD: 2020
      MYSQL_PASSWORD: 2020
      MYSQL_USER: sqluser
    volumes:
      - db:/var/lib/mysql
    networks:
      - backend
    deploy:
     replicas: 3    
     restart_policy:
      condition: on-failure  
        
networks:
  backend:
  frontend:
    driver: overlay
    
volumes:
  db:

CodePudding user response：

Having multiple instances of MySQL trying to write to the same database on disk is asking for trouble. That's why the first instance you start locks a file on the disk, so any subsequent instances will fail.

It's by design that what you're doing fails.

CodePudding user response：

The problem seems to be the volume:

volumes: db:

You dont have any defined. I use something like this:

volumes: db-data: driver: local

Good luck