MySQL Extension
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## MySQL Extension

The MySQL Extension is a Cedar Backup extension used to back up MySQL [26] databases via the Cedar Backup command line. It is intended to be run either immediately before or immediately after the standard collect action.

### Note

This extension always produces a full backup. There is currently no facility for making incremental backups. If/when someone has a need for this and can describe how to do it, I will update this extension or provide another.

The backup is done via the mysqldump command included with the MySQL product. Output can be compressed using gzip or bzip2. Administrators can configure the extension either to back up all databases or to back up only specific databases.

The extension assumes that all configured databases can be backed up by a single user. Often, the “root” database user will be used. An alternative is to create a separate MySQL “backup” user and grant that user rights to read (but not write) various databases as needed. This second option is probably your best choice.

### Warning

The extension accepts a username and password in configuration. However, you probably do not want to list those values in Cedar Backup configuration. This is because Cedar Backup will provide these values to mysqldump via the command-line `--user` and `--password` switches, which will be visible to other users in the process listing.

Instead, you should configure the username and password in one of MySQL's configuration files. Typically, that would be done by putting a stanza like this in `/root/.my.cnf`:

    [mysqldump]
    user     = root
    password = <secret>

Of course, if you are executing the backup as a user other than root, then you would create the file in that user's home directory instead.

As a side note, it is also possible to configure `.my.cnf` such that Cedar Backup can back up a remote database server:

    [mysqldump]
    host = remote.host

For this to work, you will also need to grant privileges properly for the user which is executing the backup. See your MySQL documentation for more information about how this can be done.

Regardless of whether you are using `~/.my.cnf` or `/etc/cback.conf` to store database login and password information, you should be careful about who is allowed to view that information. Typically, this means locking down permissions so that only the file owner can read the file contents (i.e. use mode `0600`).

To enable this extension, add the following section to the Cedar Backup configuration file:

    <extensions>
       <action>
          <name>mysql</name>
          <module>CedarBackup2.extend.mysql</module>
          <function>executeAction</function>
          <index>99</index>
       </action>
    </extensions>

This extension relies on the options and collect configuration sections in the standard Cedar Backup configuration file, and then also requires its own `mysql` configuration section. This is an example MySQL configuration section:

    <mysql>
       <compress_mode>bzip2</compress_mode>
       <all>Y</all>
    </mysql>

If you have decided to configure login information in Cedar Backup rather than using MySQL configuration, then you would add the username and password fields to configuration:

    <mysql>
       <user>root</user>
       <password>password</password>
       <compress_mode>bzip2</compress_mode>
       <all>Y</all>
    </mysql>

The following elements are part of the MySQL configuration section:

`user`

  Database user.

  The database user that the backup should be executed as. Even if you list more than one database (below) all backups must be done as the same user. Typically, this would be `root` (i.e. the database root user, not the system root user).

  This value is optional. You should probably configure the username and password in MySQL configuration instead, as discussed above.

  Restrictions: If provided, must be non-empty.

`password`

  Password associated with the database user.

  This value is optional. You should probably configure the username and password in MySQL configuration instead, as discussed above.

  Restrictions: If provided, must be non-empty.

`compress_mode`

  Compress mode.

  MySQL databases dumps are just specially-formatted text files, and often compress quite well using gzip or bzip2. The compress mode describes how the backed-up data will be compressed, if at all.

  Restrictions: Must be one of `none`, `gzip` or `bzip2`.

`all`

  Indicates whether to back up all databases.

  If this value is `Y`, then all MySQL databases will be backed up. If this value is `N`, then one or more specific databases must be specified (see below).

  If you choose this option, the entire database backup will go into one big dump file.

  Restrictions: Must be a boolean (`Y` or `N`).

`database`

  Named database to be backed up.

  If you choose to specify individual databases rather than all databases, then each database will be backed up into its own dump file.

  This field can be repeated as many times as is necessary. At least one database must be configured if the all option (above) is set to `N`. You may not configure any individual databases if the all option is set to `Y`.

  Restrictions: Must be non-empty.

[26] See http://www.mysql.com

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