Ask HN: Any good self-administered alternatives to Stack Overflow?

After seeing "The Fall of Stack Overflow" https://news.ycombinator.com/item?id=36855516, I'm wondering if there are any good self-administered alternatives to Stack Overflow when developing a new tool or utility?

For example, Github repos have the "Issues" tab. But, the "Issues" tab mixes bugs and other task tracking with help requests. Furthermore, the "Issues" tab isn't the question and answer format that Stack Overflow follows.

Is there perhaps an open-source Stack Overflow clone that's easily hosted on Heroku (or via Docker?)