Using why-run mode to find out what a recipe might do

why-run mode lets each resource tell you what it would do during a Chef client run, assuming certain prerequisites. This is great because it gives you a glimpse about what might really happen on your node when you run your recipe for real.

However, because Chef converges a lot of resources to a desired state, why-run will never be accurate for a complete run. Nevertheless, it might help you during development while you're adding resources step-by-step to build the final recipe.

In this section, we'll try out why-run mode to see what it tells us about our Chef client runs.

Getting ready

To try out why-run mode, you need a node where you can execute the Chef client and at least one cookbook that is available on that node.

How to do it...

Let's try to run the ntp cookbook in why-run mode:

1. Override the current run list to run the ntp recipe in why-run mode on a brand new box:

   user@server:~$ sudo chef-client -o 'recipe[ntp]' --why-run
   

   ...TRUNCATED...