Open Custom Port for TCP on CircleCI 2.0

I am bringing up the entire suite of our application via docker-compose, and would like to run our Selenium test suite against the instance that I’ve brought up. I’d like to use an actual browser. For this, I need port 8080 to be externally accessible to the CircleCI instance.

Can you please guide me on how to automatically open port 8080 when my build starts?