I'm reading this Rails tutorial, which suggests using Cloud9 for the IDE. It also recommends Heroku for hosting your app.
It turns out that Cloud9 has built-in hosting of some sort; every Cloud9 app also has a public URL, and you can run Rails yourself (albeit with Webrick by default).
As much as I Google, I can't find any details about the hosting offering Cloud9 provides. Webrick aside, what are the limits on RAM, etc.? I know Cloud9 uses Docker and Ubuntu to build a VM, but I can't find much more than that.
(As much as I am following the recommendation to use Heroku for hosting, I can't help but wonder how the two compare.)