nextcloud-docs/mariadb/content.md

What is MariaDB?

MariaDB is a community-developed fork of the MySQL relational database management system intended to remain free under the GNU GPL. Being a fork of a leading open source software system, it is notable for being led by the original developers of MySQL, who forked it due to concerns over its acquisition by Oracle. Contributors are required to share their copyright with the MariaDB Foundation.

The intent is also to maintain high compatibility with MySQL, ensuring a "drop-in" replacement capability with library binary equivalency and exact matching with MySQL APIs and commands. It includes the XtraDB storage engine for replacing InnoDB, as well as a new storage engine, Aria, that intends to be both a transactional and non-transactional engine perhaps even included in future versions of MySQL.

wikipedia.org/wiki/MariaDB

%%LOGO%%

How to use this image

start a mariadb instance

docker run --name some-mariadb -e MYSQL_ROOT_PASSWORD=mysecretpassword -d mariadb

This image includes EXPOSE 3306 (the mysql/mariadb port), so standard container linking will make it automatically available to the linked containers (as the following examples illustrate).

connect to it from an application

Since MariaDB is intended as a drop-in replacement for MySQL, it can be used with many applications.

docker run --name some-app --link some-mariadb:mysql -d application-that-uses-mysql

... or via mysql

docker run -it --link some-mariadb:mysql --rm mariadb sh -c 'exec mysql -h"$MYSQL_PORT_3306_TCP_ADDR" -P"$MYSQL_PORT_3306_TCP_PORT" -uroot -p"$MYSQL_ENV_MYSQL_ROOT_PASSWORD"'

Environment Variables

The MariaDB image uses several environment variables which are easy to miss. While not all the variables are required, they may significantly aid you in using the image. The variables use "MYSQL" since the MariaDB binary is mysqld.

MYSQL_ROOT_PASSWORD

This is the one environment variable that is required for you to use the MariaDB image. This environment variable should be what you want to set the root password for MariaDB to. In the above example, it is being set to "mysecretpassword".

MYSQL_USER, MYSQL_PASSWORD

These optional environment variables are used in conjunction to set both a MariaDB user and password, which will subsequently be granted all permissions for the database specified by the optional MYSQL_DATABASE variable. Note that if you only have one of these two environment variables, then neither will actually do anything - these two are meant to be used in conjunction with one another.

MYSQL_DATABASE

This optional environment variable denotes the name of a database to create. If a user/password was supplied (via the MYSQL_USER and MYSQL_PASSWORD environment variables) then that user account will be granted (GRANT ALL) access to this database.

Caveats

If there is no database when mariadb starts in a container, then mariadb will create the default database for you. While this is the expected behavior of mariadb, this means that it will not accept incoming connections during that time. This may cause issues when using automation tools, such as fig, that start several containers simultaneously.