PHP在某些情况下无法解析mysql容器名称 [英] PHP can not resolve mysql container name under certain circumstances

问题描述

我有旧版PHP应用程序.它使用mysqli制作mysql东西.所以在配置中，我有DSN字符串连接到mysql服务.这样

I have legacy PHP application. It used mysqli to make mysql things. So in config I have DSN string to connect to mysql service. Like that

mysql://username:password@db_hostname/dbname

Mysqli返回错误

Mysqli returns error

警告:mysqli :: real_connect():php_network_getaddresses:getaddrinfo失败:名称或服务未知

但是，如果我尝试使用此方法手动连接

But if I will try connect by hand using this

mysqli::real_connect("db_hostname")

它显示警告:mysqli :: real_connect():(HY000/1045):用户``@'172.21.0.3'的访问被拒绝(使用密码:否)

real_connect("user@db_hostname")，real_connect("mysql:db_hostname")，real_connect("mysql:host=db_hostname")无法解析主机地址.

real_connect("user@db_hostname"), real_connect("mysql:db_hostname"), real_connect("mysql:host=db_hostname") can not resolve host address.

我做错了什么?

docker-compose.yml:

docker-compose.yml:

version: "3"
services:
  nginx:
    image: nginx:1.13-alpine
    volumes:
      - ./docker/nginx/nginx.conf:/etc/nginx/conf.d/default.conf:ro
      - ./docker/nginx/errors.log:/var/logs/errors.log
      - ./docker/nginx/access.log:/var/logs/access.log
      - ./:/var/www/html
    ports:
      - "8081:80"
    command: nginx -g "daemon off;"
  php:
    build:
      context: ./docker/
      dockerfile: php.Dockerfile
    user: "1000"
    volumes:
      - ./docker/timezone.php.ini:/usr/local/etc/php/conf.d/timezone.php.ini:ro
      - /etc/timezone:/etc/timezone:ro
      - /etc/localtime:/etc/localtime:ro
      - ./:/var/www/html

  db_hostname:
    image: mysql:5.5
    user: "1000"
    environment:
      - MYSQL_DATABASE=db
      - MYSQL_ROOT_PASSWORD=root
      - MYSQL_USER=user
      - MYSQL_PASSWORD=user
    volumes:
      - ./docker/mysql:/var/lib/mysql
      - /etc/timezone:/etc/timezone:ro
      - /etc/localtime:/etc/localtime:ro

推荐答案

当您缺少链接时，将db容器与php一起使用.当您将db与PHP链接时，可以从PHP的本地主机访问它.

As you missing linking you db container with php. When you link db with PHP it will be accessible from localhost of PHP.

在这里，我修改了您的docker-compose文件，因为我到处都喜欢阿尔卑斯山;).而且我使用管理员并与db链接以验证连接，而不是代码级检查.由于我没有php docker文件，因此我正在创建包含php7的php:alpine.

Here is I modified your docker-compose file as I like alpine everywhere ;). And I use adminer and link with db to verfiy connection instead of code level checking. As i dont have you php docker file so i am creating php:alpine which contain php7.

version: "3"
services:
  nginx:
    image: nginx:1.13-alpine
    container_name: nginx
    ports:
      - "8081:80"
    command: nginx -g "daemon off;"
  db:
    image: mysql:5.5
    environment:
      MYSQL_ROOT_PASSWORD: example

  php:
    image: php:alpine
    container_name: php
    tty: true
    links:
     - db 
  adminer:
    image: adminer
    container_name: adminer
    ports:
      - 8080:8080
    links:
     - db 

然后我在php容器中安装了mysqli

Then i installed mysqli in php container

docker exec -it php ash

并在命令

docker-php-ext-install mysqli;

然后创建test.php

Then create test.php

此处服务器名称为 db .请注意，您的服务器名称将是链接到php的数据库容器名称. 如果您ping db在php容器中，它将对db容器执行ping操作.

here server name is db. Note that your server name will be what is db container name which is link to php. if you ping db in php container it will ping db container.

    <?php
$servername = "db";
$username = "root";
$password = "example";

// Create connection
$conn = new mysqli($servername, $username, $password);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 
echo "Connected successfully";
?>

现在在php容器中运行此文件.您可以挂载并运行您的php代码，但这是我所做的测试.我尝试以root用户身份登录.

Now run this file in php container. You can mount and run your php code but this is what I did for testing. And I tried as a root user.

php -f test.php

这是也与db链接的管理员

And here is adminer which also link with db

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