How to configure PHP 7 - Apache with MySQL PDO driver in Debian Docker image?
You need the Dotdeb repository in /etc/apt/sources.list on your docker image:
FROM php:7-apache# Install pdo_mysqlRUN apt-get update \ && echo 'deb http://packages.dotdeb.org jessie all' >> /etc/apt/sources.list \ && echo 'deb-src http://packages.dotdeb.org jessie all' >> /etc/apt/sources.list \ && apt-get install -y wget \ && wget https://www.dotdeb.org/dotdeb.gpg \ && apt-key add dotdeb.gpg \ && apt-get update \ && apt-get install -y php7.0-mysql \ && docker-php-ext-install pdo_mysql