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• RPM package platforms:

  • Enterprise Linux variants version 7 and higher

  • SUSE Linux Enterprise Server 12 and higher

• Debian family platforms:

  • Debian platforms

  • Ubuntu platforms

• Overview of systemd

• Configuring systemd for MySQL

• Configuring Multiple MySQL Instances Using systemd

• Migrating from mysqld_safe to systemd

On platforms for which systemd support for MySQL is installed, scripts such asmysqld_safe and the System V initialization script are unnecessary and are not installed. For example,mysqld_safe can handle server restarts, but systemd provides the same capability, and does so in a manner consistent with management of other services rather than by using an application-specific program.

One implication of the non-use ofmysqld_safe on platforms that use systemd for server management is that use of[mysqld_safe] or[safe_mysqld] sections in option files is not supported and might lead to unexpected behavior.

Because systemd has the capability of managing multiple MySQL instances on platforms for which systemd support for MySQL is installed,mysqld_multi andmysqld_multi.server are unnecessary and are not installed.

systemd provides automatic MySQL server startup and shutdown. It also enables manual server management using thesystemctl command. For example:

systemctl {start|stop|restart|status} mysqld

Alternatively, use theservice command (with the arguments reversed), which is compatible with System V systems:

service mysqld {start|stop|restart|status}

Support for systemd includes these files:

To add or change systemd options for MySQL, these methods are available:

To use a localized systemd configuration file, create the/etc/systemd/system/mysqld.service.d directory if it does not exist. In that directory, create a file that contains a[Service] section listing the desired settings. For example:

[Service]LimitNOFILE=max_open_filesPIDFile=/path/to/pid/fileNice=nice_levelLimitCore=core_file_limitEnvironment="LD_PRELOAD=/path/to/malloc/library"Environment="TZ=time_zone_setting"

The discussion here usesoverride.conf as the name of this file. Newer versions of systemd support the following command, which opens an editor and permits you to edit the file:

systemctl edit mysqld  # RPM platformssystemctl edit mysql   # Debian platforms

Whenever you create or changeoverride.conf, reload the systemd configuration, then tell systemd to restart the MySQL service:

systemctl daemon-reloadsystemctl restart mysqld  # RPM platformssystemctl restart mysql   # Debian platforms

With systemd, theoverride.conf configuration method must be used for certain parameters, rather than settings in a[mysqld],[mysqld_safe], or[safe_mysqld] group in a MySQL option file:

For additional information about using systemd rather thanmysqld_safe, seeMigrating from mysqld_safe to systemd.

You can set the following parameters inoverride.conf:

Some MySQL parameters are configured using environment variables:

There are multiple ways to specify environment variable values for use by the MySQL server process managed by systemd:

To specify options formysqld without modifying systemd configuration files directly, set or unset theMYSQLD_OPTS systemd variable. For example:

systemctl set-environment MYSQLD_OPTS="--general_log=1"systemctl unset-environment MYSQLD_OPTS

MYSQLD_OPTS can also be set in the/etc/sysconfig/mysql file.

After modifying the systemd environment, restart the server to make the changes effective:

systemctl restart mysqld  # RPM platformssystemctl restart mysql   # Debian platforms

For platforms that use systemd, the data directory is initialized if empty at server startup. This might be a problem if the data directory is a remote mount that has temporarily disappeared: The mount point would appear to be an empty data directory, which then would be initialized as a new data directory. As of MySQL 5.7.20, to suppress this automatic initialization behavior, specify the following line in the/etc/sysconfig/mysql file (create the file if it does not exist):

NO_INIT=true

This section describes how to configure systemd for multiple instances of MySQL.

To use multiple-instance capability, modify themy.cnf option file to include configuration of key options for each instance. These file locations are typical:

For example, to manage two instances namedreplica01 andreplica02, add something like this to the option file:

RPM platforms:

[mysqld@replica01]datadir=/var/lib/mysql-replica01socket=/var/lib/mysql-replica01/mysql.sockport=3307log-error=/var/log/mysqld-replica01.log[mysqld@replica02]datadir=/var/lib/mysql-replica02socket=/var/lib/mysql-replica02/mysql.sockport=3308log-error=/var/log/mysqld-replica02.log

Debian platforms:

[mysqld@replica01]datadir=/var/lib/mysql-replica01socket=/var/lib/mysql-replica01/mysql.sockport=3307log-error=/var/log/mysql/replica01.log[mysqld@replica02]datadir=/var/lib/mysql-replica02socket=/var/lib/mysql-replica02/mysql.sockport=3308log-error=/var/log/mysql/replica02.log

The replica names shown here use@ as the delimiter because that is the only delimiter supported by systemd.

Instances then are managed by normal systemd commands, such as:

systemctl start mysqld@replica01systemctl start mysqld@replica02

To enable instances to run at boot time, do this:

systemctl enable mysqld@replica01systemctl enable mysqld@replica02

Use of wildcards is also supported. For example, this command displays the status of all replica instances:

systemctl status 'mysqld@replica*'

For management of multiple MySQL instances on the same machine, systemd automatically uses a different unit file:

In the unit file,%I and%i reference the parameter passed in after the@ marker and are used to manage the specific instance. For a command such as this:

systemctl start mysqld@replica01

systemd starts the server using a command such as this:

mysqld --defaults-group-suffix=@%I ...

The result is that the[server],[mysqld], and[mysqld@replica01] option groups are read and used for that instance of the service.

Becausemysqld_safe is not installed on platforms that use systemd to manage MySQL, options previously specified for that program (for example, in an[mysqld_safe] or[safe_mysqld] option group) must be specified another way: