docker使用php缺少mysql扩展

在开发中，PHP 和 mysql 经常配合使用，那么在使用 docker 的时候 php 镜像默认是不带这个扩展的，如何进行安装呢？其实官方给出了说明：

How to install more PHP extensions

Many extensions are already compiled into the image, so it's worth checking the output of php -m or php -i before going through the effort of compiling more.

We provide the helper scripts docker-php-ext-configure, docker-php-ext-install, and docker-php-ext-enable to more easily install PHP extensions.

In order to keep the images smaller, PHP's source is kept in a compressed tar file. To facilitate linking of PHP's source with any extension, we also provide the helper script docker-php-source to easily extract the tar or delete the extracted source. Note: if you do use docker-php-source to extract the source, be sure to delete it in the same layer of the docker image.

FROM php:7.4-cli
RUN docker-php-source extract \
# do important things \
&& docker-php-source delete

嗯，又是一大段英文，大概说了但是我不想重新生成镜像来用。网上找到这段说明：

命令参数作用docker-php-sourceextract | delete加载、移除扩展文件docker-php-ext-installext安装并启用扩展docker-php-ext-enableext启用扩展docker-php-ext-configure没用过不知道命令

这些命令可以直接在镜像中使用：

1. 开启 php

docker run --name php -v path:/code -p 8080:8000 -it php

1. 启用 mysql 扩展

docker-php-source extract
cd /usr/src/php/ext
docker-php-ext-install pdo_mysql
docker-php-source delete