You may set environment variable in your job script directly as necessary, for instance:

external_database = @params:external_database@
email_settings="some hard coded settings"
...

This requires fewer configuration and is much flexible to my opinion

I think you misunderstood. I'm talking about the server itself, not the job scripts.

Specifying external database via environment variables is currently supported. Check k8s resources for details.

Specifying SSH via environment variables will also be available once SSH support is added.

However I'd like not to add other settings such as email which can be configured via GUI, as otherwise we may need to duplicate many GUI settings from environment variables, which will complicate things a lot. For those settings, I'd suggest to build a custom onedev image for your own purpose.

Also settings done via GUI may gets upgraded automatically as OneDev upgrades. Doing it via environment variables increased difficulty of maintenance.