Heroku load balancer vs Netflix zuul

I prefer approach #1 (especially since I know you're using Heroku already).

Docker is great, but the benefits are very limited if you're deploying on Heroku. The reason why is that Heroku already does everything docker does: manage dependencies, installation, and process management. Heroku does all this already for you without the extra work of Docker-izing your environment.

Regarding the load balancing: it doesn't actually matter. In both of your cases, if you want to run on Heroku, you WILL be using the Heroku load balancer. This is because there is no way to 'bypass' that layer of the Heroku stack.

If you want to use Docker / zuul, you'll need to do that OUTSIDE of Heroku for sure. This means you need to do all sorts of other stuff, find a docker host, manage your own infrastructure, etc.

So, in my mind, #1 is a better option (if you're using Heroku) because:

1. Everything is already taken care of for you.
2. You can focus on writing scalable code instead of managing all sorts of other things.
3. All your services will be in the same AWS region, so even though they will talk to each other over HTTPs, it will be VERY FAST.