MariaDB Docker image
====================
This container image includes MariaDB server 10.1 for OpenShift and general usage.
Users can choose between RHEL and CentOS based images.
Dockerfile for CentOS is called Dockerfile, Dockerfile for RHEL is called
Dockerfile.rhel7.
Environment variables and volumes
----------------------------------
The image recognizes the following environment variables that you can set during
initialization by passing `-e VAR=VALUE` to the Docker run command.
| Variable name | Description |
| :--------------------- | ----------------------------------------- |
| `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.
| Variable name | Description | Default
| :------------------------------ | ----------------------------------------------------------------- | -------------------------------
| `MYSQL_LOWER_CASE_TABLE_NAMES` | Sets how the table names are stored and compared | 0
| `MYSQL_MAX_CONNECTIONS` | The maximum permitted number of simultaneous client connections | 151
| `MYSQL_MAX_ALLOWED_PACKET` | The maximum size of one packet or any generated/intermediate string | 200M
| `MYSQL_FT_MIN_WORD_LEN` | The minimum length of the word to be included in a FULLTEXT index | 4
| `MYSQL_FT_MAX_WORD_LEN` | The maximum length of the word to be included in a FULLTEXT index | 20
| `MYSQL_AIO` | Controls the `innodb_use_native_aio` setting value in case the native AIO is broken. See http://help.directadmin.com/item.php?id=529 | 1
| `MYSQL_TABLE_OPEN_CACHE` | The number of open tables for all threads | 400
| `MYSQL_KEY_BUFFER_SIZE` | The size of the buffer used for index blocks | 32M (or 10% of available memory)
| `MYSQL_SORT_BUFFER_SIZE` | The size of the buffer used for sorting | 256K
| `MYSQL_READ_BUFFER_SIZE` | The size of the buffer used for a sequential scan | 8M (or 5% of available memory)
| `MYSQL_INNODB_BUFFER_POOL_SIZE`| The size of the buffer pool where InnoDB caches table and index data | 32M (or 50% of available memory)
| `MYSQL_INNODB_LOG_FILE_SIZE` | The size of each log file in a log group | 8M (or 15% of available available)
| `MYSQL_INNODB_LOG_BUFFER_SIZE` | The size of the buffer that InnoDB uses to write to the log files on disk | 8M (or 15% of available memory)
| `MYSQL_DEFAULTS_FILE` | Point to an alternative configuration file | /etc/my.cnf
| `MYSQL_BINLOG_FORMAT` | Set sets the binlog format, supported values are `row` and `statement` | statement
You can also set the following mount points by passing the `-v /host:/container` flag to Docker.
| Volume mount point | Description |
| :----------------------- | -------------------- |
| `/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.**
Usage
---------------------------------
For this, we will assume that you are using the `rhscl/mariadb-100-rhel7` image.
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-100-rhel7
```
This 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`](https://dev.mysql.com/doc/refman/5.6/en/mysql-install-db.html)
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`.
MariaDB auto-tuning
-------------------
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.
| Variable name | Configuration parameter | Relative value
| :-------------------------------| ------------------------- | --------------
| `MYSQL_KEY_BUFFER_SIZE` | `key_buffer_size` | 10%
| `MYSQL_READ_BUFFER_SIZE` | `read_buffer_size` | 5%
| `MYSQL_INNODB_BUFFER_POOL_SIZE` | `innodb_buffer_pool_size` | 50%
| `MYSQL_INNODB_LOG_FILE_SIZE` | `innodb_log_file_size` | 15%
| `MYSQL_INNODB_LOG_BUFFER_SIZE` | `innodb_log_buffer_size` | 15%
MySQL root user
---------------------------------
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.
Changing passwords
------------------
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.
Default my.cnf file
-------------------
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`
Changing the replication binlog_format
--------------------------------------
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.