## What this PR does
The MariaDB chart's my.cnf has not been read by the server since the
mariadb-operator bump to v0.28.1. Up to v0.0.27 the operator mounted the
referenced ConfigMap key as `/etc/mysql/conf.d/my.cnf` whatever the key
was called. Since v0.0.28 the file takes the key's own name, so the
chart's key `config` became `/etc/mysql/conf.d/config`. The server's
`!includedir` reads only `*.cnf` files, so it skipped it, and every
instance has been running on stock MariaDB defaults. On the default
`t1.nano` preset that means a 128M buffer pool inside a 128Mi memory
limit.
This renames the key to `my.cnf` in the ConfigMap and in the MariaDB CR.
The file content is unchanged. I started all four shipped versions
(10.6.24, 10.11.15, 11.4.9, 11.8.5) with the rendered file under a 128m
memory limit, and each one came up with the chart's values. The
MySQL-only options in the file log a warning and are otherwise ignored.
They and the deprecated `innodb_flush_method` are tracked in #4842.
Tests: a helm-unittest suite pins the key on both sides, and the mariadb
chainsaw suite gets a step that compares `@@innodb_buffer_pool_size` on
the running server with the value in the rendered my.cnf.
This changes behaviour on every existing instance, see the release note.
Each instance rolls its pods once because the projected volume in the
pod template changes: replicas first, then the primary with a
switchover. After that the server runs with every setting in the chart's
file. Instances created before the operator bump (May 2024) ran with
these settings before. Newer ones never did.
Closes#4836
### Screenshots
Not a UI change.
### Downstream repositories
- [x] No downstream repository is affected by this change
- [ ] [cozystack/website](https://github.com/cozystack/website) -
follow-up:
- [ ]
[cozystack/terraform-provider-cozystack](https://github.com/cozystack/terraform-provider-cozystack)
- follow-up:
- [ ]
[cozystack/ansible-cozystack](https://github.com/cozystack/ansible-cozystack)
- follow-up:
- [ ] [cozystack/ccp](https://github.com/cozystack/ccp) - follow-up:
- [ ] [cozystack/talm](https://github.com/cozystack/talm) - follow-up:
- [ ] [cozystack/cozyhr](https://github.com/cozystack/cozyhr) -
follow-up:
- [ ] [cozystack/cozy-proxy](https://github.com/cozystack/cozy-proxy) -
follow-up:
- [ ]
[cozystack/cozystack-telemetry-server](https://github.com/cozystack/cozystack-telemetry-server)
- follow-up:
- [ ]
[cozystack/external-apps-example](https://github.com/cozystack/external-apps-example)
- follow-up:
- [ ] [cozystack/examples](https://github.com/cozystack/examples) -
follow-up:
- [ ] [cozystack/community](https://github.com/cozystack/community) -
follow-up:
### Release note
```release-note
fix(mariadb): the chart's my.cnf is applied again. Since mariadb-operator v0.28.1 it was mounted under a name the server ignores, so MariaDB instances ran on stock defaults. Every existing instance rolls its pods once on upgrade (replicas first, then the primary with a switchover) and then runs with the chart's settings. That changes behaviour: buffer pool, redo log, connection limits and caches are sized from the instance's resources; sql_mode becomes NO_ENGINE_SUBSTITUTION, so strict mode is off and invalid values are truncated with a warning instead of rejected; innodb_flush_log_at_trx_commit=2 can lose up to about a second of committed transactions if the node crashes; innodb_fast_shutdown=0 makes every pod shutdown slower.
```
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Bug Fixes**
* MariaDB configuration is now stored and read using the `my.cnf` key. A
verification check confirms the running server applies the configured
buffer-pool size.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Aleksei Sviridkin
6144805bea