docker run --name mysql --restart always -p 3306:3306 -v /var/lib/mysql:/var/lib/mysql -e MYSQL_ROOT_PASSWORD=password -d mysql:5.7.14

version: '2'

services:
    wordpress:
        image: wordpress
        external_links:
            - mysql:mysql
        ports:
            - 80:80
    environment:
        WORDPRESS_DB_USER: root
        WORDPRESS_DB_PASSWORD: password
    volumes:
        - /var/www/somesite.com:/var/www/html

Starting somesitecom_wordpress_1
Attaching to somesitecom_wordpress_1
wordpress_1  |
wordpress_1  | Warning: mysqli::mysqli(): (HY000/2002): Connection refused in - on line 19
wordpress_1  |
wordpress_1  | MySQL Connection Error: (2002) Connection refused