Joomla with docker and Mysql??

Hello,
I would like to use Joomla in docker.
I add variable "JOOMLA_DB_USER", "JOOMLA_DB_NAME" and "JOOMLA_DB_PASSWORD" in Environment variables but I need to use "JOOMLA_DB_HOST" for linked with mysql.
Can I use mysql out of a container or I need to create a mysql container too?
Thanks