Sometimes, your Puppet manifest doesn't do exactly what you expected, or perhaps someone else has checked in changes you didn't know about. Either way, it's good to know exactly what Puppet is going to do before it does it.
When you are retrofitting Puppet into an existing infrastructure, you might not know whether Puppet is going to update a config file or restart a production service. Any such change could result in unplanned downtime. Also, sometimes, manual configuration changes are made on a server that Puppet would overwrite.
To avoid these problems, you can use Puppet's noop
mode, which means
no operation
or do nothing. When run with the noop option, Puppet only reports what it would do, but doesn't actually do anything. One caveat here is that even during a noop
run, pluginsync
still runs and any lib
directories in modules will be synced to nodes. This will update external fact definitions and possibly Puppet's types and providers. If you are using...