DOMAIN name issue behind proxy

Based on my understanding Coreteza webapp is running under nodejs. If we directly expose nodejs to public access, it is easy being attacked. So I deploy Corteza in one namespace in Kubernetes and reverse proxy in other namespace with reverse proxy setting pointing to Corteza webapp root path. But when I come to Corteza deployment, I have no clue in setting of DOMAIN environment variables. I am thinking this DOMAIN env variables is the core piece of info how nodejs call javascript and other web components. But under cloud environment , how can we make this DOMAIN env variable dynamic to accept any request forward by reverse proxy?

I have an nginx reverse proxy and I set the DOMAIN variable for Corteza to the url I use to access the proxy. In my case it is all internal, but Corteza works just fine.

using subdomain or route level reverse proxy?

Iā€™m using subdomains.