旧应用mysql_connect连接失败求助：PHP5.6 Docker环境适配修复

问题背景 #

正在为一款即将重写的老旧应用搭建本地Docker环境，该应用依赖PHP5.6和旧版MySQL。已解决初始问题，但需要能运行该应用的Docker镜像支持，同时遇到数据库连接的核心问题。

连接测试代码 #

测试数据库连接的代码如下：

require_once("/var/www/html/class/autoload.php");
$database = $_ENV['DB_HOST'];
$DBuser = $_ENV["MYSQL_USER"];
$DBpass = $_ENV["MYSQL_USER"];
$link = mysql_connect($database, $DBuser, $DBpass, null);

if (!$link) {
    echo "Error: Unable to connect to MySQL." . PHP_EOL;
    echo "Debugging errno: " . mysql_error() . PHP_EOL;
    exit;
}

报错信息 #

运行上述代码时出现错误：

Warning: mysql_connect(): No such file or directory in /var/www/html/docker_build/test_db.php on line 10
Error: Unable to connect to MySQL. Debugging errno: No such file or directory

改用mysqli_connect可正常连接，但项目全程使用mysql_系列函数，无法批量替换。该应用在 staging 和生产服务器可正常运行，本地VM复刻环境时，原Dockerfile因安全更新失效。

当前Docker配置 #

docker-compose.yml #

version: "3"

services:
  webserver:
    build: 
      context: ${DOCKER_BUILD_ROOT}/bin/${DOCKER_PHPVERSION}
    container_name: ${DOCKER_PHPVERSION}
    restart: 'always'
    ports:
      - "${HOST_MACHINE_UNSECURE_HOST_PORT}:80"
      - "${HOST_MACHINE_SECURE_HOST_PORT}:443"
    links: 
      - database
    volumes: 
      - ${DOCUMENT_ROOT-.}:/var/www/html
      - ${PHP_INI-./docker_build/config/php/php.ini}:/usr/local/etc/php/php.ini
      - ${VHOSTS_DIR-./docker_build/config/vhosts}:/etc/apache2/sites-enabled
      - ${APACHE_LOG_DIR-./docker_build/logs/apache2}:/var/log/apache2
    # user: "1000:1000"
    user: root
  database:
    build:
      context: "${DOCKER_BUILD_ROOT}/bin/${DOCKER_DATABASE}"
    container_name: 'database'
    restart: 'always'
    ports:
      - "${DOCKER_LOCALHOST}:${HOST_MACHINE_MYSQL_PORT}:3306"
    volumes: 
      - ${MYSQL_CONF_FILE-./docker_build/config/mysql/mysql.conf.d/mysqld.cnf}:/etc/mysql/mysql.conf.d/mysqld.cnf
      - ${MYSQL_DATA_DIR-./docker_build/data/mysql}:/var/lib/mysql
      - ${MYSQL_LOG_DIR-./docker_build/logs/mysql}:/var/log/mysql
      - ${MYSQL_INIT_DIR-./docker_build/config/mysql/ini}:/docker-entrypoint-initdb.d
    environment:
      MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD}
      MYSQL_DATABASE: ${MYSQL_DATABASE}
      MYSQL_USER: ${MYSQL_USER}
      MYSQL_PASSWORD: ${MYSQL_PASSWORD}
  phpmyadmin:
    image: phpmyadmin/phpmyadmin
    container_name: 'phpmyadmin'
    links:
      - database
    environment:
      PMA_HOST: database
      PMA_PORT: 3306
      PMA_USER: ${MYSQL_USER}
      PMA_PASSWORD: ${MYSQL_PASSWORD}
      MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD}
      MYSQL_USER: ${MYSQL_USER}
      MYSQL_PASSWORD: ${MYSQL_PASSWORD}
    ports:
      - '8080:80'
    volumes: 
      - /sessions
      - ${PHP_INI-./docker_build/config/php/php.ini}:/usr/local/etc/php/conf.d/php-phpmyadmin.ini
  redis:
    container_name: 'redis'
    image: redis:latest
    ports:
      - "${DOCKER_LOCALHOST}:${HOST_MACHINE_REDIS_PORT}:6380"

PHP5.6 Dockerfile #

FROM php:5.6-apache

RUN apt-get -y update && apt-get upgrade -y

# Install tools && libraries
RUN apt-get -y install --fix-missing apt-utils nano wget dialog \
    build-essential git curl libcurl3 libcurl3-dev zip \
    libmcrypt-dev libsqlite3-dev libsqlite3-0 mysql-client \
    zlib1g-dev libicu-dev libfreetype6-dev libjpeg62-turbo-dev libpng-dev \
    && rm -rf /var/lib/apt/lists/*

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

# PHP5 Extensions

RUN docker-php-ext-install curl \
    && docker-php-ext-install tokenizer \
    && docker-php-ext-install json \
    && docker-php-ext-install mcrypt \
    && docker-php-ext-install pdo_mysql \
    && docker-php-ext-install pdo_sqlite \
    && docker-php-ext-install mysql \
    && docker-php-ext-install mysqli \
    && docker-php-ext-install zip \
    && docker-php-ext-install -j$(nproc) intl \
    && docker-php-ext-install mbstring \
    && docker-php-ext-configure gd --with-freetype-dir=/usr/include/ --with-jpeg-dir=/usr/include/ \
    && docker-php-ext-install -j$(nproc) gd \
    && pecl install xdebug-2.5.5 && docker-php-ext-enable xdebug

# Enable apache modules
RUN a2enmod rewrite headers

RUN apt-get update && apt-get install -y \
    mediainfo \
    jhead \
    imagemagick \
    ffmpeg

RUN usermod -u 1000 www-data

EXPOSE 80

# initialize server script. designed to be run after volumes are mounted.
# runs composer install and runs apache2 foreground.
# ENTRYPOINT ["/usr/sbin/apache2ctl", "-D", "FOREGROUND"]
ENTRYPOINT ["./docker_build/config/server_ini.sh"]

已排查情况 #

• 检查过.env、php.ini及Linux系统配置
• 怀疑MySQL Socket配置异常，但命令行mysql -uroot -p可正常连接
• 优先需要Docker解决方案，原镜像已废弃，可提供.env与.ini配置文件协助排查

内容的提问来源于stack exchange，提问作者Mike