Sorry, I just can't buy into the dripping sarcasm of emphasizing that it's only a forum. Yeah, it's a forum. Forums are big software applications. It's not unreasonable to distribute the forum backend with Docker.
It's only the most advanced, most thought-out web forum. It's leaps and bounds ahead of phpbb and Invision because the lead developer knows that details matter. That includes testing, automatic updates, spam protection, user experience, and all that stuff that old PHP boards suck at.