NestJS provides the necessary documentation for working with different environments (development, production, etc.) using external configuration files and environment variables. So, if you have already taken a look there, then the below provided cases, will give you a hand to start implementing your (relatively simple) project as well.
A circular dependency occurs when two classes depend on each other. For example, class A needs class B, and class B also needs class A. Circular dependencies can arise in Nest between modules and between providers.
Here, you can get a nice grasp on how you can avoid the Circular Dependency in Nest.js.