Ask HN: How do I use the Firebase Hacker News API with their 3.0 version

Since Firebase was bought by Google they have released a 3.0 version of their SDK which no longer just takes a URL to a DB but also takes an apiKey. I've done a fair bit of googling and reading the docs but I can't find a way to connect to the Hacker News API with the new SDK as I'm not sure where I'm supposed to get an apiKey from.