Enable custom my.cnf

[derekperkins]

You should be able to supply my.cnf files to be mounted at any level. Unlike flags, this should be an append only list, so configs mounted globally are mounted first, followed in order of specificity. MySQL itself will be responsible for deduplicating / overriding individual options.

The helm chart only allows for one my.cnf file to be mounted here, but this should allow for multiple files.
https://github.com/vitessio/vitess/blob/master/helm/vitess/values.yaml#L251-L254