Yaybu gently guides you into writing configurations that are safe to run over and over. Follow your guidelines and you'll only restart services when they need restarting.
You want to know that a configuration is safe? Yaybu does too! Not only can you see the final fully compiled configuration but you can also, as much as is possible, simulate what that deployment will do without it modifying the server!
Yaybu isn't just a command line tool. You can use it as a library in a larger application, and it works fantastically well with Django and Celery.