Configuration is set in config/secrets.yml via environment variables.
We use the dotenv gem to load variables specified in .env into the rails app, only in the development and test environments. This makes sure they are only loaded for the context of the running rails app and that they don't pollute the shell environment.
In the Next app, if not using Docker, you'll want to copy over the .env.local.example file to .env.local and set the appropriate
variables there.