TL;DR
We moved a Rails app into an unbuilt engine of a new blank slate container app to allow new parts of our app to live next to it as engines as well. It has been working great for us!
I have a sample app rails_container_and_engines of the result's structure on github.
Skip to the pitfalls and discoveries section to read about some of the speed bumps we during our transition. Interested in the why and how? Read on!
IntelliJ has a feature called modules: "a functional unit which you can compile, run, test and debug independently."

A module in IntelliJ is a top-level view on a part of a codebase. IntelliJ is for Java, which is why I do not typically use it. I use Rubymine - no similar functionality exists here... but a way around that!
Ask for help
- We just upgraded one project from Devise 1.1 to Devise 1.2 and reported "many problems which blew up all sorts of stuff". It was bad enough we had to rollback. Are there others with failure or success stories for this upgrade?
- Can you rate limit EC2 nodes using an Elastic Load Balancer? We'd like to cap the amount of traffic that can be sent to an app instance. I'm thinking advanced use cases like this are probably why you run your own haproxy instead of using ELBs.
- How are people running database migrations in their engine gems? I know rails 3.1 promises to bring this to the table, but is there a backport gem we can use?
Interesting
- iOS 4.2 is out! We're looking forward to trying it on the iPad (finally).
