nextcloud-docs/mariadb/content.md

What is MariaDB?

MariaDB Server is one of the most popular database servers in the world. It’s made by the original developers of MySQL and guaranteed to stay open source. Notable users include Wikipedia, DBS Bank, and ServiceNow.

The intent is also to maintain high compatibility with MySQL, ensuring a library binary equivalency and exact matching with MySQL APIs and commands. MariaDB developers continue to develop new features and improve performance to better serve its users.

%%LOGO%%

How to use this image

Start a %%IMAGE%% server instance

Starting a MariaDB instance is simple:

$ docker run -p 127.0.0.1:3306:3306  --name some-%%REPO%% -e MARIADB_ROOT_PASSWORD=my-secret-pw -d %%IMAGE%%:tag

or:

$ docker network create some-network # Create the network
$ docker run --net some-network --name some-%%REPO%% -e MARIADB_ROOT_PASSWORD=my-secret-pw -d %%IMAGE%%:tag

... where some-network is newly created network (other than bridge as the default network), some-%%REPO%% is the name you want to assign to your container, my-secret-pw is the password to be set for the MariaDB root user and tag is the tag specifying the MariaDB version you want. See the list above for relevant tags.

Connect to MariaDB from the MySQL/MariaDB command line client

The following command starts another %%IMAGE%% container instance and runs the mysql command line client against your original %%IMAGE%% container, allowing you to execute SQL statements against your database instance:

$ docker run -it --network some-network --rm %%IMAGE%% mysql -hsome-%%REPO%% -uexample-user -p

... where some-%%REPO%% is the name of your original %%IMAGE%% container (connected to the some-network Docker network).

This image can also be used as a client for non-Docker or remote instances:

$ docker run -it --rm %%IMAGE%% mysql -hsome.mysql.host -usome-mysql-user -p

More information about the MariaDB command-line client can be found in the MariaDB Knowledge Base

%%STACK%%

Run docker stack deploy -c stack.yml %%REPO%% (or docker-compose -f stack.yml up), wait for it to initialize completely, and visit http://swarm-ip:8080, http://localhost:8080, or http://host-ip:8080 (as appropriate).

Container shell access and viewing MariaDB logs

The docker exec command allows you to run commands inside a Docker container. The following command line will give you a bash shell inside your %%IMAGE%% container:

$ docker exec -it some-%%REPO%% bash

The log is available through Docker's container log:

$ docker logs some-%%REPO%%

Using a custom MariaDB configuration file

The startup configuration is specified in the file /etc/mysql/my.cnf, and that file in turn includes any files found in the /etc/mysql/conf.d directory that end with .cnf. Settings in files in this directory will augment and/or override settings in /etc/mysql/my.cnf. If you want to use a customized MariaDB configuration, you can create your alternative configuration file in a directory on the host machine and then mount that directory location as /etc/mysql/conf.d inside the %%IMAGE%% container.

If /my/custom/config-file.cnf is the path and name of your custom configuration file, you can start your %%IMAGE%% container like this (note that only the directory path of the custom config file is used in this command):

$ docker run --name some-%%REPO%% -v /my/custom:/etc/mysql/conf.d -e MARIADB_ROOT_PASSWORD=my-secret-pw -d %%IMAGE%%:tag

This will start a new container some-%%REPO%% where the MariaDB instance uses the combined startup settings from /etc/mysql/my.cnf and /etc/mysql/conf.d/config-file.cnf, with settings from the latter taking precedence.

Configuration without a cnf file

Many configuration options can be passed as flags to mysqld. This will give you the flexibility to customize the container without needing a cnf file. For example, if you want to change the default encoding and collation for all tables to use UTF-8 (utf8mb4) just run the following:

$ docker run --name some-%%REPO%% -e MYSQL_ROOT_PASSWORD=my-secret-pw -d %%IMAGE%%:tag --character-set-server=utf8mb4 --collation-server=utf8mb4_unicode_ci

If you would like to see a complete list of available options, just run:

$ docker run -it --rm %%IMAGE%%:tag --verbose --help

Environment Variables

When you start the %%IMAGE%% image, you can adjust the initialization of the MariaDB instance by passing one or more environment variables on the docker run command line. Do note that none of the variables below will have any effect if you start the container with a data directory that already contains a database: any pre-existing database will always be left untouched on container startup.

From tags 10.2.38, 10.3.29, 10.4.19, 10.5.10 onwards, and all 10.6 tags, the MARIADB_* equivalent variables are provided. MARIADB_* variants will always be used in preference to MYSQL_* variants.

One of MARIADB_ROOT_PASSWORD, MARIADB_ALLOW_EMPTY_ROOT_PASSWORD, or MARIADB_RANDOM_ROOT_PASSWORD (or equivalents, including *_FILE), is required. The other environment variables are optional.

MARIADB_ROOT_PASSWORD / MYSQL_ROOT_PASSWORD

This specifies the password that will be set for the MariaDB root superuser account. In the above example, it was set to my-secret-pw.

MARIADB_ALLOW_EMPTY_ROOT_PASSWORD / MYSQL_ALLOW_EMPTY_PASSWORD

Set to a non-empty value, like yes, to allow the container to be started with a blank password for the root user. NOTE: Setting this variable to yes is not recommended unless you really know what you are doing, since this will leave your MariaDB instance completely unprotected, allowing anyone to gain complete superuser access.

MARIADB_RANDOM_ROOT_PASSWORD / MYSQL_RANDOM_ROOT_PASSWORD

Set to a non-empty value, like yes, to generate a random initial password for the root user. The generated root password will be printed to stdout (GENERATED ROOT PASSWORD: .....).

MARIADB_ROOT_HOST / MYSQL_ROOT_HOST

This is the hostname part of the root user created. By default this is %, however it can be set to any default MariaDB allowed hostname component.

MARIADB_DATABASE / MYSQL_DATABASE

This variable allows you to specify the name of a database to be created on image startup.

MARIADB_USER / MYSQL_USER, MARIADB_PASSWORD / MYSQL_PASSWORD

These are used in conjunction to create a new user and to set that user's password. Both user and password variables are required for a user to be created. This user will be granted all access (corresponding to GRANT ALL) to the MARIADB_DATABASE database.

Do note that there is no need to use this mechanism to create the root superuser, that user gets created by default with the password specified by the MARIADB_ROOT_PASSWORD / MYSQL_ROOT_PASSWORD variable.

MARIADB_INITDB_SKIP_TZINFO / MYSQL_INITDB_SKIP_TZINFO

By default, the entrypoint script automatically loads the timezone data needed for the CONVERT_TZ() function. If it is not needed, any non-empty value disables timezone loading.

Docker Secrets

As an alternative to passing sensitive information via environment variables, _FILE may be appended to the previously listed environment variables, causing the initialization script to load the values for those variables from files present in the container. In particular, this can be used to load passwords from Docker secrets stored in /run/secrets/<secret_name> files. For example:

$ docker run --name some-mysql -e MARIADB_ROOT_PASSWORD_FILE=/run/secrets/mysql-root -d %%IMAGE%%:tag

Currently, this is only supported for MARIADB_ROOT_PASSWORD, MARIADB_ROOT_HOST, MARIADB_DATABASE, MARIADB_USER, and MARIADB_PASSWORD (and MYSQL_* equivalents of these).

Initializing a fresh instance

When a container is started for the first time, a new database with the specified name will be created and initialized with the provided configuration variables. Furthermore, it will execute files with extensions .sh, .sql, .sql.gz, and .sql.xz that are found in /docker-entrypoint-initdb.d. Files will be executed in alphabetical order. .sh files without file execute permission are sourced rather than executed. You can easily populate your %%IMAGE%% services by mounting a SQL dump into that directory and provide custom images with contributed data. SQL files will be imported by default to the database specified by the MARIADB_DATABASE / MYSQL_DATABASE variable.

Caveats

Where to Store Data

Important note: There are several ways to store data used by applications that run in Docker containers. We encourage users of the %%IMAGE%% images to familiarize themselves with the options available, including:

• Let Docker manage the storage of your database data by writing the database files to disk on the host system using its own internal volume management. This is the default and is easy and fairly transparent to the user. The downside is that the files may be hard to locate for tools and applications that run directly on the host system, i.e. outside containers.
• Create a data directory on the host system (outside the container) and mount this to a directory visible from inside the container. This places the database files in a known location on the host system, and makes it easy for tools and applications on the host system to access the files. The downside is that the user needs to make sure that the directory exists, and that e.g. directory permissions and other security mechanisms on the host system are set up correctly.

The Docker documentation is a good starting point for understanding the different storage options and variations, and there are multiple blogs and forum postings that discuss and give advice in this area. We will simply show the basic procedure here for the latter option above:

1. Create a data directory on a suitable volume on your host system, e.g. /my/own/datadir.

2. Start your %%IMAGE%% container like this:

   $ docker run --name some-%%REPO%% -v /my/own/datadir:/var/lib/mysql -e MARIADB_ROOT_PASSWORD=my-secret-pw -d %%IMAGE%%:tag
   

The -v /my/own/datadir:/var/lib/mysql part of the command mounts the /my/own/datadir directory from the underlying host system as /var/lib/mysql inside the container, where MariaDB by default will write its data files.

No connections until MariaDB init completes

If there is no database initialized when the container starts, then a default database will be created. While this is the expected behavior, this means that it will not accept incoming connections until such initialization completes. This may cause issues when using automation tools, such as docker-compose, which start several containers simultaneously.

Usage against an existing database

If you start your %%IMAGE%% container instance with a data directory that already contains a database (specifically, a mysql subdirectory), the $MARIADB_ROOT_PASSWORD variable should be omitted from the run command line; it will in any case be ignored, and the pre-existing database will not be changed in any way.

Creating database dumps

Most of the normal tools will work, although their usage might be a little convoluted in some cases to ensure they have access to the mysqld server. A simple way to ensure this is to use docker exec and run the tool from the same container, similar to the following:

$ docker exec some-%%REPO%% sh -c 'exec mysqldump --all-databases -uroot -p"$MARIADB_ROOT_PASSWORD"' > /some/path/on/your/host/all-databases.sql

Restoring data from dump files

For restoring data. You can use the docker exec command with the -i flag, similar to the following:

$ docker exec -i some-%%REPO%% sh -c 'exec mysql -uroot -p"$MARIADB_ROOT_PASSWORD"' < /some/path/on/your/host/all-databases.sql