use defaults-extra-file instead of defaults-file

[ofrzeta]

use defaults-extra-file for creds instead of defaults-file so mysqldump still reads the global defaults for setting stuff like "set-gtid-purged=OFF"

[greg-1-anderson]

Seems okay to me. The only question I have is, what version of mysql was this option first supported? Do we risk breaking old mysql versions? If so, do we care? I found this exists in mysql 5.6, 5.7 and 8.0. It looks like Drupal 8 still supports mysql 5.5, so that implies Drush does too. Not sure if this option is available there.

If that's not an issue, then this is an improvement.

[ofrzeta]

Thanks for the review. Looks like MySQL 5.5 has the option: http://download.nust.na/pub6/mysql/doc/refman/5.5/en/option-files.html (also found some references to it in the docu of 5.1).

[weitzman]

Seems reasonable to me as well but someone's setup always breaks when we change mysql config stuff like this. Mulling it.

[ofrzeta]

Any progress on this?

[greg-1-anderson]

If we're concerned about unlikely edge cases causing a problem, perhaps we could introduce a Drush configuration option to revert to the old directive.

[weitzman]

I did some research. We started out with --defaults-extra-file as proposed in this PR. See #365. It got changed to --defaults-file in #2387. Given the history, I'm uninclined to change it back. Maybe we could make this a config pref.

[greg-1-anderson]

OK the history from #2387 is that some users put sql credentials in their my.cnf file. If we go back to using --defaults-extra-file, then Drush breaks for all of those users, because credentials from the my.cnf file take precedence over credentials provided in --defaults-extra-file.

As disappointing as this is, I think it is unavoidable that we close this PR and look for another solution.

[weitzman]

Seems like drush sql:dump --extra-dump="--set-gtid-purged=OFF" would fix this, right? This option can be added to a site's drush config if the typing gets error-prone or tedious.

[weitzman]

This approach wont work. Lets continue in #4410