Postgres connection error on 'bundle exec rails c'

Correct me if I’m wrong but I thought I could set it on runtime first. So I need to set it on app.yml first to then be able to modify it on runtime?

The forum is quite busy so I was hoping to be able to set it on runtime first before setting it permanently in the ENV.

Any hints about the syntax? Can this just be

DISCOURSE_PROMETHEUS_TRUSTED_IP_ALLOWLIST_REGEX: 123.145.167.189