This container image includes MariaDB 10.2 SQL database server for OpenShift and general usage. Users can choose between RHEL and CentOS based images. The RHEL image is available in the Red Hat Container Catalog as registry.access.redhat.com/rhscl/mariadb-102-rhel7. The CentOS image is then available on Docker Hub as centos/mariadb-102-centos7.
This container image provides a containerized packaging of the MariaDB mysqld daemon and client application. The mysqld server daemon accepts connections from clients and provides access to content from MySQL databases on behalf of the clients. You can find more information on the MariaDB project from the project Web site (https://mariadb.org/).
For this, we will assume that you are using the MariaDB 10.2 container image from the
Red Hat Container Catalog called rhscl/mariadb-102-rhel7.
If you want to set only the mandatory environment variables and not store
the database in a host directory, execute the following command:
$ docker run -d --name mariadb_database -e MYSQL_USER=user -e MYSQL_PASSWORD=pass -e MYSQL_DATABASE=db -p 3306:3306 rhscl/mariadb-102-rhel7This will create a container named mariadb_database running MySQL with database
db and user with credentials user:pass. Port 3306 will be exposed and mapped
to the host. If you want your database to be persistent across container executions,
also add a -v /host/db/path:/var/lib/mysql/data argument. This will be the MySQL
data directory.
If the database directory is not initialized, the entrypoint script will first
run mysql_install_db
and setup necessary database users and passwords. After the database is initialized,
or if it was already present, mysqld is executed and will run as PID 1. You can
stop the detached container by running docker stop mariadb_database.
The image recognizes the following environment variables that you can set during
initialization by passing -e VAR=VALUE to the Docker run command.
MYSQL_USER
User name for MySQL account to be created
MYSQL_PASSWORD
Password for the user account
MYSQL_DATABASE
Database name
MYSQL_ROOT_PASSWORD
Password for the root user (optional)
The following environment variables influence the MySQL configuration file. They are all optional.
MYSQL_LOWER_CASE_TABLE_NAMES (default: 0)
Sets how the table names are stored and compared
MYSQL_MAX_CONNECTIONS (default: 151)
The maximum permitted number of simultaneous client connections
MYSQL_MAX_ALLOWED_PACKET (default: 200M)
The maximum size of one packet or any generated/intermediate string
MYSQL_FT_MIN_WORD_LEN (default: 4)
The minimum length of the word to be included in a FULLTEXT index
MYSQL_FT_MAX_WORD_LEN (default: 20)
The maximum length of the word to be included in a FULLTEXT index
MYSQL_AIO (default: 1)
Controls the innodb_use_native_aio setting value in case the native AIO is broken. See http://help.directadmin.com/item.php?id=529
MYSQL_TABLE_OPEN_CACHE (default: 400)
The number of open tables for all threads
MYSQL_KEY_BUFFER_SIZE (default: 32M or 10% of available memory)
The size of the buffer used for index blocks
MYSQL_SORT_BUFFER_SIZE (default: 256K)
The size of the buffer used for sorting
MYSQL_READ_BUFFER_SIZE (default: 8M or 5% of available memory)
The size of the buffer used for a sequential scan
MYSQL_INNODB_BUFFER_POOL_SIZE (default: 32M or 50% of available memory)
The size of the buffer pool where InnoDB caches table and index data
MYSQL_INNODB_LOG_FILE_SIZE (default: 8M or 15% of available available)
The size of each log file in a log group
MYSQL_INNODB_LOG_BUFFER_SIZE (default: 8M or 15% of available memory)
The size of the buffer that InnoDB uses to write to the log files on disk
MYSQL_DEFAULTS_FILE (default: /etc/my.cnf)
Point to an alternative configuration file
MYSQL_BINLOG_FORMAT (default: statement)
Set sets the binlog format, supported values are row and statement
MYSQL_LOG_QUERIES_ENABLED (default: 0)
To enable query logging set this to 1
You can also set the following mount points by passing the -v /host:/container flag to Docker.
/var/lib/mysql/data
MySQL data directory
Notice: When mouting a directory from the host into the container, ensure that the mounted directory has the appropriate permissions and that the owner and group of the directory matches the user UID or name which is running inside the container.
When the MySQL image is run with the --memory parameter set and you didn't
specify value for some parameters, their values will be automatically
calculated based on the available memory.
MYSQL_KEY_BUFFER_SIZE (default: 10%)
key_buffer_size
MYSQL_READ_BUFFER_SIZE (default: 5%)
read_buffer_size
MYSQL_INNODB_BUFFER_POOL_SIZE (default: 50%)
innodb_buffer_pool_size
MYSQL_INNODB_LOG_FILE_SIZE (default: 15%)
innodb_log_file_size
MYSQL_INNODB_LOG_BUFFER_SIZE (default: 15%)
innodb_log_buffer_size
The root user has no password set by default, only allowing local connections.
You can set it by setting the MYSQL_ROOT_PASSWORD environment variable. This
will allow you to login to the root account remotely. Local connections will
still not require a password.
To disable remote root access, simply unset MYSQL_ROOT_PASSWORD and restart
the container.
Since passwords are part of the image configuration, the only supported method
to change passwords for the database user (MYSQL_USER) and root user is by
changing the environment variables MYSQL_PASSWORD and MYSQL_ROOT_PASSWORD,
respectively.
Changing database passwords through SQL statements or any way other than through the environment variables aforementioned will cause a mismatch between the values stored in the variables and the actual passwords. Whenever a database container starts it will reset the passwords to the values stored in the environment variables.
With environment variables we are able to customize a lot of different parameters
or configurations for the mysql bootstrap configurations. If you'd prefer to use
your own configuration file, you can override the MYSQL_DEFAULTS_FILE env
variable with the full path of the file you wish to use. For example, the default
location is /etc/my.cnf but you can change it to /etc/mysql/my.cnf by setting
MYSQL_DEFAULTS_FILE=/etc/mysql/my.cnf
This image can be extended using source-to-image.
For example, to build a customized MariaDB database image my-mariadb-rhel7
with a configuration in ~/image-configuration/ run:
$ s2i build ~/image-configuration/ rhscl/mariadb-102-rhel7 my-mariadb-rhel7The directory passed to s2i build can contain these directories:
mysql-cfg/
When starting the container, files from this directory will be used as
a configuration for the mysqld daemon.
envsubst command is run on this file to still allow customization of
the image using environmental variables
mysql-pre-init/
Shell scripts (*.sh) available in this directory are sourced before
mysqld daemon is started.
mysql-init/
Shell scripts (*.sh) available in this directory are sourced when
mysqld daemon is started locally. In this phase, use ${mysql_flags}
to connect to the locally running daemon, for example mysql $mysql_flags < dump.sql
Variables that can be used in the scripts provided to s2i:
$mysql_flags
arguments for the mysql tool that will connect to the locally running mysqld during initialization
$MYSQL_RUNNING_AS_MASTER
variable defined when the container is run with run-mysqld-master command
$MYSQL_RUNNING_AS_SLAVE
variable defined when the container is run with run-mysqld-slave command
$MYSQL_DATADIR_FIRST_INIT
variable defined when the container was initialized from the empty data dir
During s2i build all provided files are copied into /opt/app-root/src
directory into the resulting image. If some configuration files are present
in the destination directory, files with the same name are overwritten.
Also only one file with the same name can be used for customization and user
provided files are preferred over default files in
/usr/share/container-scripts/mysql/- so it is possible to overwrite them.
Same configuration directory structure can be used to customize the image
every time the image is started using docker run. The directory has to be
mounted into /opt/app-root/src/ in the image
(-v ./image-configuration/:/opt/app-root/src/).
This overwrites customization built into the image.
In order to secure the connection with SSL, use the extending feature described above. In particular, put the SSL certificates into a separate directory:
sslapp/mysql-certs/server-cert-selfsigned.pem
sslapp/mysql-certs/server-key.pemAnd then put a separate configuration file into mysql-cfg:
$> cat sslapp/mysql-cfg/ssl.cnf
[mysqld]
ssl-key=${APP_DATA}/mysql-certs/server-key.pem
ssl-cert=${APP_DATA}/mysql-certs/server-cert-selfsigned.pemSuch a directory sslapp can then be mounted into the container with -v,
or a new container image can be built using s2i.
Some applications may wish to use row binlog_formats (for example, those built
with change-data-capture in mind). The default replication/binlog format is
statement but to change it you can set the MYSQL_BINLOG_FORMAT environment
variable. For example MYSQL_BINLOG_FORMAT=row. Now when you run the database
with master replication turned on (ie, set the Docker/container cmd to be
run-mysqld-master) the binlog will emit the actual data for the rows that change
as opposed to the statements (ie, DML like insert...) that caused the change.
The mysqld deamon in the container logs to the standard output, so the log is available in the container log. The log can be examined by running:
docker logs <container>Dockerfile and other sources for this container image are available on https://github.com/sclorg/mariadb-container. In that repository, Dockerfile for CentOS is called Dockerfile, Dockerfile for RHEL is called Dockerfile.rhel7.