Online service to execute Ruby scripts

Question

I am investigating the possibility to start a backup up server remotely in case the main server fails. The idea is:

1. Amazon Route 53 monitors the main server
2. The server fails, which triggers an alarm in Cloud Watch
3. Cloud Watch pushes a new Simple Message Nofication
4. The SNS sends a HTTP/S request somewhere which triggers execution of a Ruby script
5. The script spins off a new instance somewhere in the cloud (but not in AWS)

Is there a service available online which triggered by a HTTP/S request would execute an arbitrary Ruby script?

The service would work in a similar way to Twilio, only it would execute a script instead of sending a SMS or making a call.