Scalr integrates with Chef, the configuration management tool offered by Opscode. If you are on the IPO plan or above and use hosted Chef, you can now enjoy the taste of Chef ruby recipes directly in Scalr. Chef is second to none when it comes to manage software servers. Update? Security patches? No problemo.

Integration between Scalr and Chef – Create a control center where you can see your infrastructure, track spending, perform update and manage software servers. All this comes with Scalr gorgeous UI!
Chef-based Role builder – Add the credentials of your Chef servers and start boostraping servers by specifying runlists. Use the Chef side-tab on your Roles. Runlists will run every time a new instance of these roles is provisionned.
Chef integration from the farm builder – Pull recipes from Chef-server to build and manage your infrastructure. Chef follows the recipes in your runlist, adding software ingredients and puttings the servers in the state you want. Use its power to manage the configuration on your instances.