MySQL 8.0 Docker容器持续重启问题求助

问题 #

按照DigitalOcean教程《如何在Ubuntu 20.04上使用Docker Compose搭建Laravel、Nginx和MySQL》操作，仅将PHP版本改为8.1、MySQL版本改为8.0。本地开发环境测试正常，但部署到Droplet后，digitalocean.com/php和nginx:alpine容器运行正常，唯独mysql:8.0容器处于持续重启状态。

错误日志 #

容器重启时的日志（执行docker logs -f）

• 2022-08-13 06:35:20+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 8.0.30-1.el8 started.
• 2022-08-13 06:35:20+00:00 [Note] [Entrypoint]: Switching to dedicated user ‘mysql’
• 2022-08-13 06:35:20+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 8.0.30-1.el8 started.
• ‘/var/lib/mysql/mysql.sock’ -> ‘/var/run/mysqld/mysqld.sock’

直接执行docker run --restart=always mysql:8.0时的错误

• 2022-08-13 06:57:37+00:00 [Note] [Entrypoint]: Entrypoint script - for MySQL Server 8.0.30-1.el8 started.
• 2022-08-13 06:57:38+00:00 [Note] [Entrypoint]: Switching to dedicated user ‘mysql’
• 2022-08-13 06:57:38+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 8.0.30-1.el8 started.
• 2022-08-13 06:57:38+00:00 [ERROR] [Entrypoint]: Database is uninitialized and password option is not specified
  You need to specify one of the following:
• MYSQL_ROOT_PASSWORD
• MYSQL_ALLOW_EMPTY_PASSWORD
• MYSQL_RANDOM_ROOT_PASSWORD

配置文件 #

Dockerfile

FROM php:8.1-fpm

# Copy composer.lock and composer.json
COPY composer.lock composer.json /var/www/

# Set working directory
WORKDIR /var/www

# Install dependencies
RUN apt-get update && apt-get install -y \
    build-essential \
    libpng-dev \
    libjpeg62-turbo-dev \
    libfreetype6-dev \
    locales \
    zip \
    jpegoptim optipng pngquant gifsicle \
    vim \
    unzip \
    git \
    curl \
    libzip-dev

# Clear cache
RUN apt-get clean && rm -rf /var/lib/apt/lists/*

# Install composer
RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer

# Add user for laravel application
RUN groupadd -g 1000 www
RUN useradd -u 1000 -ms /bin/bash -g www www

# Copy existing application directory contents
COPY . /var/www

# Copy existing application directory permissions
COPY --chown=www:www . /var/www

# Change current user to www
USER www

# Expose port 9000 and start php-fpm server
EXPOSE 9000
CMD ["php-fpm"]

docker-compose.yml

version: '3'
services:
  
  #PHP Service
  app:
    build:
      context: .
      dockerfile: Dockerfile
    image: digitalocean.com/php
    container_name: app
    restart: unless-stopped
    tty: true
    environment:
      SERVICE_NAME: app
      SERVICE_TAGS: dev
    working_dir: /var/www
    volumes:
      - ./:/var/www
      - ./php/local.ini:/usr/local/etc/php/conf.d/local.ini
    networks:
      - app-network

  #Nginx Service
  webserver:
    image: nginx:alpine
    container_name: webserver
    restart: unless-stopped
    tty: true
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - ./:/var/www
      - ./nginx/conf.d/:/etc/nginx/conf.d/
    networks:
      - app-network

  #MySQL Service
  db:
    image: mysql:8.0
    container_name: db
    restart: unless-stopped
    tty: true
    ports:
      - "3306:3306"
    environment:
      MYSQL_DATABASE: laravel
      MYSQL_ROOT_PASSWORD: 123123
      SERVICE_TAGS: dev
      SERVICE_NAME: mysql
    volumes:
      - dbdata:/var/lib/mysql/
      - ./mysql/my.cnf:/etc/mysql/my.cnf
    networks:
      - app-network

#Docker Networks
networks:
  app-network:
    driver: bridge
#Volumes
volumes:
  dbdata:
    driver: local

解决方案 #

1. 清理旧MySQL数据卷
   本地测试生成的dbdata卷可能残留旧数据，与MySQL 8.0初始化逻辑冲突。执行以下命令彻底清理并重启：

   docker-compose down -v
   docker-compose up -d
   

2. 检查自定义my.cnf的权限与兼容性
   挂载的本地my.cnf可能存在权限问题（容器内mysql用户无读取权限）或配置不符合MySQL 8.0规范：

   • 先临时删除docker-compose.yml中db服务的./mysql/my.cnf:/etc/mysql/my.cnf挂载项，重启容器验证是否恢复正常。
   • 若恢复正常，调整本地my.cnf权限（执行chmod 644 ./mysql/my.cnf），并移除其中MySQL 8.0不支持的配置项（如过时的sql_mode设置）。

3. 验证环境变量传递
   虽然配置中已声明MYSQL_ROOT_PASSWORD，但可能因yaml语法错误导致变量未正确传递。执行以下命令检查：

   docker-compose run db env | grep MYSQL_ROOT_PASSWORD
   

   若未输出123123，检查docker-compose.yml的缩进格式是否正确。

4. 检查Droplet磁盘空间
   磁盘空间不足会导致MySQL无法写入数据，执行df -h查看磁盘使用情况，清理冗余文件或扩容Droplet。

内容的提问来源于stack exchange，提问作者Kaung San Hein