I was recently working on a Drupal project that had some internal DNS managed via hosts file. Tell me about it. Having no publicly accessible DNS or IP creates a challenge when your SaaS based Jenkins runs the tests.
The solution for this is a little custom work in your FeatureContext constructor and a BeforeScenario method.
And a little glue in the behat.yml to pass the custom hostHeader variable to the FeatureContext. Make sure that you're also setting the IP of the server for base_url and you're all set.
You can use this same pattern to pass around other variables from behat.yml to your FeatureContext.