Add support for external postgress server in values chart

[mpsOxygen]

Summary
It would be very useful to add support in the chart to configure an external postgress db. For example I use cloudnative-pg to provision postgress DBs in my cluster.

Background and rationale
The cloudnative-pg operator does a way better job of managing postgress instances in kubernetes than the bitnami chart.

Description
In the values file I would like to have the option to disable the postgress datbase and specify data for an external postgress server.

Acceptance criteria
Being able to install the chart with an external database.

[antgamdia]

Hi @mpsOxygen , thanks for creating the proposal.

From memory, I'd say we already have support for external databases in our chart. You can set both externalDatabase.port and externalDatabase.host having set postgresql.enabled=false.

Please give it a try (have a look at the chart templates, helper.tpl file, etc) and let us know if it works for you.
Also, please also feel free to contribute and send a PR with an updated chart (in the bitnami/charts repo, so that it get published sooner).

[mpsOxygen]

I have tried it like that but it still creates the postgres pod even with postgresql.enabled=false and host and port set.

[antgamdia]

Ah, that's a pity :S We usually don't test our Kubeapps chart against external databases, so, likely, the support for it has been accidentally removed when refactoring the chart some time ago.

As said, please feel free to contribute and send a PR to the repo and thanks for reporting the issue!

[brunomedeirosdedalus]

As far as I know the variables needed to setup the external DB are not available on the values.yaml. I have made a PR for it #7743, I have some more ideas on how to improve this part, if there is any interest on it.