feature: added possibility to define the name of the instance and backup storage class

[leonsteinhaeuser]

As part of our customization's to the PostgreSQL cluster, we discovered that it is currently not possible to change the storage class for predefined instances. Since our cluster infrastructure contains more than one storage class with different underlying storage technologies, it is necessary for us to select a specific storage class. We found that this is already possible when we define our own instance, but we thought it would be more useful to simply add this functionality to the chart.

[benjaminjb]

Hello, thanks for the PR, I've made a few comments on it to (a) correct a slight mistake and (b) bring it in line with the multiline if...end format we've established.

Also, at least for the backup repo section, have you ever tried to put all the necessary info into the pgBackRestConfig field in the values.yaml? I wonder how that would work for that specific part of the template.

[leonsteinhaeuser]

@benjaminjb thank you very much for your reply and review. I will look at it asap and update the PR.

[leonsteinhaeuser]

@benjaminjb I have accepted your changes.

Also, at least for the backup repo section, have you ever tried to put all the necessary info into the pgBackRestConfig field in the values.yaml?

I did that and it worked quite well. Since we already supported custom volume sizes at the top level, I thought it would be useful to support customization for storage classes as well.