You know how it goes. You tweak a cookbook to support your new server and upload it to your Chef Server. Your new node converges just fine and you're a happy pal. Well, until your older production server picks up your modified cookbook during an automated Chef Client run and spits its guts at you. Obviously, you forgot that your old production server was still using the cookbook you tweaked. Luckily, there is the
knife preflight command, which can show you all nodes using a certain cookbook before you upload it to your Chef Server.
For the following example, we assume that you've at least one role using the
ntp cookbook in its run list and that you've multiple servers having this role ...