mysqldump-lvm does not support federated

[Andrew Garner]

If there are one or more federated tables, mysqldump-lvm will fail on invoking mysqldump with an error along the lines of:

/usr/bin/mysqldump[14494]: mysqldump: Couldn't execute 'show create table `fed_test`': Unknown storage engine 'FEDERATED' (1286)

Or:

/usr/bin/mysqldump[13866]: mysqldump: Got error: 1286: Unknown storage engine 'FEDERATED' when using LOCK TABLES

This is due to federated not being enabled on the temporary instance running on the snapshot.

This is currently done to avoid accidentally writing to files used by the production instance - so the snapshot instance generates a minimally "safe" config - injecting any custom innodb options as necessary. This can be fixed by enabling federated (e.g. adding loose-federated to the generated my.cnf) - but there are probably other cases where a more general solution is needed.

I think it makes sense to just add some mysqld-opts = to the [mysqld] section to customize the commandline options. Also, being able to include some custom my.cnf or specify other key=value options may be useful as well - injecting arbitrary key/value options into the my.cnf is already supported in the amsterdam branch although not exposed to the end-user.

[Andrew Garner (muzazzi)]

Pushed feature branch here: https://github.com/holland-backup/holland/tree/feature/lp_1235385_lvm_support_federated

Specifically holland's mysqld control code unconditionally adds the loose-federated option to attempt to enable federated support where it is available.

This should be included in the 1.0.12 release.