You can use Scalr's deployment functionality to orchestrate code deployments to your farms, and create workflows that use hudson/jenkins and only deploy if all tests pass.
To automatically deploy code when you push to a repository, you can set post-commit hooks in svn and git that trigger a new deployment.
svn
The following script deploys your application when you commit code to your subversion repository, and emails the release manager.
svn update
git
Code deployment for git:
git update
Labels