Database DSN should be more securely generated/assembled

[gtherond]

Hi team,

Currently, when setting a new casdoor instance using the helm-chart, we need to get the database credentials in plain text in order for the DSN on the configmap to be created from it.

That is kind of a burden as it let you get plaintext password on your values.yaml file.

Would it be doable to rather use kubernetes secrets already existing or generate it?

I'd like to be able to get something like this as an additional option:

database:
  secret:
    name: <string>
    generate: <bool>

As it needs a bit of additional works on the current helm chart so, I can work on it if you want.

[hsluoyz]

@gtherond sounds good. Plz make a PR. Need to keep compatible with the old mode

[gtherond]

Sounds good to me!

[gtherond]

I've got something quite nice, although I'm having a bug with the DSN and a specific condition to test, but it's not abandoned :D