- image: mysql:5.6
        environment:
         - MYSQL_ROOT_PASSWORD=ubuntu
         - MYSQL_USER=user
         - MYSQL_PASSWORD=password

MySQL init process done. Ready for start up. ......mysqld: ready for
connections.
Version: '5.6.38'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306
MySQL Community Server (GPL)

mysql --version

mysql: command not found