Adding update procedure on startup

[flavioaiello]

The entrypoint is responsible for database initialization in case no database is provided, thus it would make sense to be responsible for the database upgrade as well.

[tianon]

I agree in theory, but in practice this implementation is going to be quite a drain on users' systems -- I think we instead need to do something similar to docker-library/mysql#416 (and frankly, I'd rather resolve that one first and copy the implementation here afterwards unless there's a compelling reason why MariaDB would have a differing implementation).

[flavioaiello]

I fully agree that both engine variants could and should be solved in the same manner. But why checking version etc. with shell scripting if the update process is able to do same by itself?

The only difference during startup is the line below, in case the upgrade did already took place:
This installation of MySQL is already upgraded to 10.3.8-MariaDB, use --force if you still need to run mysql_upgrade,
The temporary process will be then terminated as soon the check was done. Okay I see, the difference in terms of load is that an additional process is spawn only to determine if the upgrade is required or not.

[tianon]

Because it avoids starting up `mysqld` unnecessarily, which is pretty heavy.

[CReimer]

The issue for MySQL got closed. MySQL seems to do something like mysql_upgrade by itself on startup.

Any chance something like this gets adopted by MariaDB anytime soon?

[J0WI]

https://jira.mariadb.org/browse/MDEV-9394

[tianon]

Closing in favor of https://jira.mariadb.org/browse/MDEV-9394 -- this is too heavy for us to do by default (starting mysqld twice on every container startup).

See also #271, which made implementing these types of customizations in a descendent image much easier to accomplish in a reliable/maintainable way.