Yeah, it also wasn’t difficult to do the equivalent without heroku via post-commit hook.
Honestly, even setting up autoscaling via AMIs isn’t that hard. Docker is in many ways the DevOps equivalent of the JS front end world: excessive complexity, largely motivated by people who have no idea what the alternatives are.
I was working on Rails apps before AMIs or Heroku.
Me too. I'm not responding specifically to you with the parent comment. That said, "autoscaling", as a concept, didn't really exist prior to AWS AMIs (or Heroku, I guess).
My point is that a lot of devs reach to Docker because they think they need it to do these "hard" things, and they immediately get lost in the complexity of that ecosystem, having never realized that there might be a better way.