One of my favorite bloggers on the subject of continuous integration, The Build Doctor, posed this question in a recent post:
Continuous Integration in the cloud: good idea?
The topic of running a CI server in a virtualized environment, such as with Amazon's EC2 service, is an interesting issue, particularly in the Hudson community. About 10 months ago Kohsuke announced the Hudson EC2 plugin which has seen slow, but steady development since then, including support for the Ubuntu Enterprise Cloud which was added to the plugin in a release last Monday.
As The Build Doctor and his readers point out, continuous integration is a difficult task to offload into the cloud because of the immense hardware demands constant building and testing presents. That said, Hudson does very effectively manage spinning slaves up and down on demand if you've configured it as such. Implication being: running Hudson in the cloud may be more efficient to meet peak demands without needing to run a large farm of machines.
If you're interested in trying out the EC2 plugin, check out Sonatype's post on Nexus Open Source and Hudson on EC2 might be a good start.
Would you run Hudson in the cloud?