Read Postgres DB details from environment variables every time

[ameyp]

I'd like it if the chart supported the following:

• Pass postgres details (host, db name, username, password) as environment variables
• Generate the app.ini using these details each time the pod boots up

My usecase for this is that I'd like to rotate the postgres database credentials regularly. I'm using hashicorp vault to generate dynamic credentials for the database role I'd like to use for gitea, and every time I request credentials from vault, I get a randomly-generated username and password. My plan is to request fresh credentials at a regular cadence, set environment variables for the pod, restart the gitea pod, and have it generate the app.ini using the environment variables. I'm also open to discussing a different approach if you have one in mind.

If this is something you'd find valuable, I'd be happy to create a pull request.

[ameyp]

Another option is reading the details from an existing secret specified as a Chart value. The crucial part for my usecase is that the variables should be re-read each time the pod is started, not only at first run.