“Refused to connect” using ChromeDriver, Capybara & Docker Compose

I'm trying to make the move from PhantomJS to Headless Chrome and have run into a bit of a snag. For local testing, I'm using Docker Compose to get all dependent services up and running. To provision Google Chrome, I'm using an image that bundles both it and ChromeDriver together while serving it on port I'm trying to make the move from PhantomJS to H