Coonect pgboucer with SSL/TLS in PosgreSQL

[dtrabanca]

Hello,
I have a question or a possible improvement that I think you should add to the Helm template.
We currently use pgboucer to connect to the databases, but... there is a small problem that does not show how to mount the volumes where the secrets are stored with the different SSL connection certificates for the database.
Currently, extra volumes can be added, but volumes cannot be mounted. This would be very useful because once the volume containing the different certificates is mounted, the paths of each file can be passed in the pgboucer environment variables.
Greetings, thanks.

[khvn26]

@dtrabanca Thanks for the suggestion! We'll look into solving this and will happily review any PRs.

Opened a more general #278.